diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 08bd951..44e699a 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -20,3 +20,7 @@ jobs:
       run: make
     - name: run
       run: ./JunLang
+    - uses: actions/upload-artifact@v4
+      with:
+        name: JunLang
+        path: ./JunLang
diff --git a/.gitignore b/.gitignore
index 427bdb6..28bb9dc 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,3 @@
 build
 .idea
-cmake-build-debug
+cmake-build-debug
\ No newline at end of file
diff --git a/README.md b/README.md
index c93ec78..69ee42b 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,5 @@
 # JunLang
+[![C/C++ CI](https://github.com/Jun-Software/JunLang/actions/workflows/c-cpp.yml/badge.svg)](https://github.com/Jun-Software/JunLang/actions/workflows/c-cpp.yml)
 
 [中文版](https://github.com/Jun-Software/JunLang/blob/master/README-zh.md)
 
diff --git a/src/identifiers/addition.hpp b/src/identifiers/addition.hpp
index 4392497..bc36d71 100644
--- a/src/identifiers/addition.hpp
+++ b/src/identifiers/addition.hpp
@@ -3,34 +3,12 @@
  * By lemonorangeapple
 **/
 void addition(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is already declared
-    bool undeclared = true;
-    for (int i = 0; i <= variableCount; i++) {
-        // If the variable is already declared, add the value
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // Add the integer value to the variable
-                variables[i].value += atoi((*(it + 2)).c_str());
-                undeclared = false;
-                break;
-            }
-            // If the value is not an integer, check if it is a variable
-            else {
-                undeclared = true;
-                for (int j = 0; j <= variableCount; j++) {
-                    // If the variable is already declared, add the value
-                    if (variables[j].name == *(it + 2)) {
-                        variables[i].value += variables[j].value;
-                        undeclared = false;
-                        break;
-                    }
-                }
-            }
-        }
+    string next = *(it + 2);
+    string _this = *(it + 1);
+    if (isInteger(next)) {
+        variables[_this] += atoi((next).c_str());
     }
-    // If the variable is not declared, throw an error
-    if (undeclared) {
-        cerr << "[ERROR] Variable undeclared. " << endl;
+    else {
+        variables[_this] += variables[next];
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/division.hpp b/src/identifiers/division.hpp
index d31ad64..c75f770 100644
--- a/src/identifiers/division.hpp
+++ b/src/identifiers/division.hpp
@@ -3,43 +3,12 @@
  * By lemonorangeapple
 **/
 void division(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches the one in the expression
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // Divide the value by the integer
-                variables[i].value /= atoi((*(it + 2)).c_str());
-                // Set undeclared to false
-                undeclared = false;
-                // Break out of the loop
-                break;
-            }
-            // If the value is not an integer
-            else {
-                // Set undeclared to true
-                undeclared = true;
-                // Loop through the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches the one in the expression
-                    if (variables[j].name == *(it + 2)) {
-                        // Divide the value by the value of the other variable
-                        variables[i].value /= variables[j].value;
-                        // Set undeclared to false
-                        undeclared = false;
-                        // Break out of the loop
-                        break;
-                    }
-                }
-            }
-        }
+    string next = *(it + 2);
+    string _this = *(it + 1);
+    if (isInteger(next)) {
+        variables[_this] /= atoi((next).c_str());
     }
-    // If the variable is undeclared
-    if (undeclared) {
-        // Print an error message
-        cerr << "[ERROR] Variable undeclared. " << endl;
+    else {
+        variables[_this] /= variables[next];
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/end_loop.hpp b/src/identifiers/end_loop.hpp
index 4184240..e2d6a63 100644
--- a/src/identifiers/end_loop.hpp
+++ b/src/identifiers/end_loop.hpp
@@ -7,24 +7,13 @@ void end_loop(vector<string>::iterator it, ifstream &file) {
     if (!loopFlag.empty()) {
         // Check if loop flag is true
         if (loopFlag.top() == true) {
-            // Check if loop variable name is correct
-            for (int i = 0; i <= variableCount; i++) {
-                if (variables[i].name == loopVariableName.top()) {
-                    // Check if loop variable value is 0
-                    if (variables[i].value == 0) {
-                        // Pop loop flag
-                        loopFlag.pop();
-                        break;
-                    }
-                    else {
-                        // Check if loop line is empty
-                        if (!loopLine.empty()) {
-                            // Seekg to loop line
-                            file.seekg(int(loopLine.top()) - 2);
-                        }
-                        break;
-                    }
-                }
+            if (variables[loopVariableName.top()] == 0) {
+                // Pop loop flag
+                loopFlag.pop();
+            }
+            else if (!loopLine.empty()) {
+                // Seekg to loop line
+                file.seekg(int(loopLine.top()) - 3);
             }
         }
         else {
diff --git a/src/identifiers/equal.hpp b/src/identifiers/equal.hpp
index c7a1df5..3191fb6 100644
--- a/src/identifiers/equal.hpp
+++ b/src/identifiers/equal.hpp
@@ -3,53 +3,14 @@
  * By lemonorangeapple
 **/
 void equal(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // Loop through the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches
-                    if (variables[j].name == *(it + 3)) {
-                        // Set the undeclared flag to false
-                        undeclared = false;
-                        // Set the value to true if the variable values are equal
-                        variables[j].value = (variables[i].value == atoi((*(it + 2)).c_str()));
-                        break;
-                    }
-                }
-            }
-            // Check if the value is a variable
-            else {
-                // Set the undeclared flag to true
-                undeclared = true;
-                // Loop through the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches
-                    if (variables[j].name == *(it + 2)) {
-                        // Loop through the variables
-                        for (int k = 0; k <= variableCount; k++) {
-                            // Check if the variable name matches
-                            if (variables[k].name == *(it + 3)) {
-                                // Set the undeclared flag to false
-                                undeclared = false;
-                                // Set the value to true if the variable values are equal
-                                variables[k].value = (variables[i].value == variables[j].value);
-                                break;
-                            }
-                        }
-                        break;
-                    }
-                }
-            }
-        }
+    string a = *(it + 1), b = *(it + 2), c = *(it + 3);
+    if (isInteger(b)) {
+        variables[c] = (variables[a] == atoi(b.c_str()));
     }
-    // If the variable is undeclared, print an error message
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else if (isInteger(a)){
+        variables[c] = (atoi(a.c_str()) == variables[b]);
+    }
+    else {
+        variables[c] = (variables[a] == variables[b]);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/equal_or_greater.hpp b/src/identifiers/equal_or_greater.hpp
index 2c638b2..225dfc2 100644
--- a/src/identifiers/equal_or_greater.hpp
+++ b/src/identifiers/equal_or_greater.hpp
@@ -3,56 +3,14 @@
  * By lemonorangeapple
 **/
 void equal_or_greater(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through all the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches the first argument
-        if (variables[i].name == *(it + 1)) {
-            // Check if the second argument is an integer
-            if (isInteger(*(it + 2))) {
-                // Loop through all the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches the third argument
-                    if (variables[j].name == *(it + 3)) {
-                        // Set the undeclared flag to false
-                        undeclared = false;
-                        // Set the value of the third argument to the value of the first argument
-                        variables[j].value = (variables[i].value >= atoi((*(it + 2)).c_str()));
-                        // Break out of the loop
-                        break;
-                    }
-                }
-            }
-            // Check if the second argument is a variable
-            else {
-                // Set the undeclared flag to true
-                undeclared = true;
-                // Loop through all the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches the second argument
-                    if (variables[j].name == *(it + 2)) {
-                        // Loop through all the variables
-                        for (int k = 0; k <= variableCount; k++) {
-                            // Check if the variable name matches the third argument
-                            if (variables[k].name == *(it + 3)) {
-                                // Set the undeclared flag to false
-                                undeclared = false;
-                                // Set the value of the third argument to the value of the first argument
-                                variables[k].value = (variables[i].value >= variables[j].value);
-                                // Break out of the loop
-                                break;
-                            }
-                        }
-                        // Break out of the inner loop
-                        break;
-                    }
-                }
-            }
-        }
+    string a = *(it + 1), b = *(it + 2), c = *(it + 3);
+    if (isInteger(b)) {
+        variables[c] = (variables[a] >= atoi(b.c_str()));
     }
-    // If the variable is undeclared, print an error message
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else if (isInteger(a)){
+        variables[c] = (atoi(a.c_str()) >= variables[b]);
+    }
+    else {
+        variables[c] = (variables[a] >= variables[b]);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/equal_or_less.hpp b/src/identifiers/equal_or_less.hpp
index 4db1dd9..f62a4f7 100644
--- a/src/identifiers/equal_or_less.hpp
+++ b/src/identifiers/equal_or_less.hpp
@@ -3,59 +3,14 @@
  * By lemonorangeapple
 **/
 void equal_or_less(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches
-        if (variables[i].name == *(it + 1)) {
-            // Check if the second argument is an integer
-            if (isInteger(*(it + 2))) {
-                // Loop through the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the third argument matches
-                    if (variables[j].name == *(it + 3)) {
-                        // Set the undeclared flag to false
-                        undeclared = false;
-                        // Set the value of the third argument to the comparison of the first and second arguments
-                        variables[j].value = (variables[i].value <= atoi((*(it + 2)).c_str()));
-                        // Break out of the loop
-                        break;
-                    }
-                }
-                // Break out of the loop
-                break;
-            }
-            // If the second argument is not an integer
-            else {
-                // Set the undeclared flag to true
-                undeclared = true;
-                // Loop through the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the second argument matches
-                    if (variables[j].name == *(it + 2)) {
-                        // Loop through the variables
-                        for (int k = 0; k <= variableCount; k++) {
-                            // Check if the third argument matches
-                            if (variables[k].name == *(it + 3)) {
-                                // Set the undeclared flag to false
-                                undeclared = false;
-                                // Set the value of the third argument to the comparison of the first and second arguments
-                                variables[k].value = (variables[i].value <= variables[j].value);
-                                // Break out of the loop
-                                break;
-                            }
-                        }
-                        // Break out of the loop
-                        break;
-                    }
-                }
-            }
-        }
+    string a = *(it + 1), b = *(it + 2), c = *(it + 3);
+    if (isInteger(b)) {
+        variables[c] = (variables[a] <= atoi(b.c_str()));
     }
-    // If the variable is undeclared
-    if (undeclared) {
-        // Print an error message
-        cerr << "[Error] Variable undeclared." << endl;
+    else if (isInteger(a)){
+        variables[c] = (atoi(a.c_str()) <= variables[b]);
+    }
+    else {
+        variables[c] = (variables[a] <= variables[b]);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/greater.hpp b/src/identifiers/greater.hpp
index 1c9fd4b..5893b3e 100644
--- a/src/identifiers/greater.hpp
+++ b/src/identifiers/greater.hpp
@@ -3,59 +3,14 @@
  * By lemonorangeapple
 **/
 void _greater(vector<string>::iterator it, ifstream &file) {
-    // Check if the first variable is undeclared
-    bool undeclared = true;
-    // Loop through all variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the first variable is equal to the name of the variable
-        if (variables[i].name == *(it + 1)) {
-            // Check if the second variable is an integer
-            if (isInteger(*(it + 2))) {
-                // Loop through all variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the second variable is equal to the name of the variable
-                    if (variables[j].name == *(it + 3)) {
-                        // Set undeclared to false
-                        undeclared = false;
-                        // Set the value of the second variable to the greater of the first and the second
-                        variables[j].value = (variables[i].value > atoi((*(it + 2)).c_str()));
-                        // Break out of the loop
-                        break;
-                    }
-                }
-                // Break out of the loop
-                break;
-            }
-            // If the second variable is not an integer
-            else {
-                // Set undeclared to true
-                undeclared = true;
-                // Loop through all variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the second variable is equal to the name of the variable
-                    if (variables[j].name == *(it + 2)) {
-                        // Loop through all variables
-                        for (int k = 0; k <= variableCount; k++) {
-                            // Check if the third variable is equal to the name of the variable
-                            if (variables[k].name == *(it + 3)) {
-                                // Set undeclared to false
-                                undeclared = false;
-                                // Set the value of the third variable to the greater of the first and the third
-                                variables[k].value = (variables[i].value > variables[j].value);
-                                // Break out of the loop
-                                break;
-                            }
-                        }
-                        // Break out of the loop
-                        break;
-                    }
-                }
-            }
-        }
+    string a = *(it + 1), b = *(it + 2), c = *(it + 3);
+    if (isInteger(b)) {
+        variables[c] = (variables[a] > atoi(b.c_str()));
     }
-    // If the first variable is undeclared
-    if (undeclared) {
-        // Print an error message
-        cerr << "[Error] Variable undeclared." << endl;
+    else if (isInteger(a)){
+        variables[c] = (atoi(a.c_str()) > variables[b]);
+    }
+    else {
+        variables[c] = (variables[a] > variables[b]);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/identifiers.hpp b/src/identifiers/identifiers.hpp
index 3a79493..654fbd5 100644
--- a/src/identifiers/identifiers.hpp
+++ b/src/identifiers/identifiers.hpp
@@ -4,8 +4,6 @@
 #include "output.hpp"
 // Wrap
 #include "wrap.hpp"
-// New
-#include "new.hpp"
 // Set
 #include "set.hpp"
 // Input
diff --git a/src/identifiers/if.hpp b/src/identifiers/if.hpp
index 915b891..456b574 100644
--- a/src/identifiers/if.hpp
+++ b/src/identifiers/if.hpp
@@ -3,28 +3,12 @@
  * By lemonorangeapple
 **/
 void _if(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches
-        if (variables[i].name == *(it + 1)) {
-            // Check if the variable value is 0
-            if (variables[i].value == 0) {
-                // Push false if the variable value is 0
-                ifFlag.push(false);
-            }
-            else {
-                // Push true if the variable value is not 0
-                ifFlag.push(true);
-            }
-            // Break out of the loop
-            undeclared = false;
-            break;
-        }
+    if (variables[*(it + 1)] == 0) {
+        // Push false if the variable value is 0
+        ifFlag.push(false);
     }
-    // If the variable is undeclared, throw an error
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else {
+        // Push true if the variable value is not 0
+        ifFlag.push(true);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/input.hpp b/src/identifiers/input.hpp
index cc0ce34..a685213 100644
--- a/src/identifiers/input.hpp
+++ b/src/identifiers/input.hpp
@@ -3,20 +3,7 @@
  * By lemonorangeapple
 **/
 void input(vector<string>::iterator it, ifstream &file) {
-    // Check if variable is already declared
-    bool undeclared = true;
-    for (int i = 0; i <= variableCount; i++) {
-        // If variable is found, assign value to it
-        if (variables[i].name == *(it + 1)) {
-            long double temp;
-            cin >> temp;
-            variables[i].value = temp;
-            undeclared = false;
-            break;
-        }
-    }
-    // If variable is not found, throw error
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
-    }
+    long double temp;
+    cin >> temp;
+    variables[*(it + 1)] = temp;
 }
\ No newline at end of file
diff --git a/src/identifiers/less.hpp b/src/identifiers/less.hpp
index 3776ee6..ce2e65f 100644
--- a/src/identifiers/less.hpp
+++ b/src/identifiers/less.hpp
@@ -3,53 +3,14 @@
  * By lemonorangeapple
 **/
 void _less(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through all the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // Loop through all the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches
-                    if (variables[j].name == *(it + 3)) {
-                        // Set the undeclared flag to false
-                        undeclared = false;
-                        // Set the value of the variable to the comparison
-                        variables[j].value = (variables[i].value < atoi((*(it + 2)).c_str()));
-                        break;
-                    }
-                }
-            }
-            // If the value is not an integer
-            else {
-                // Set the undeclared flag to true
-                undeclared = true;
-                // Loop through all the variables
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches
-                    if (variables[j].name == *(it + 2)) {
-                        // Loop through all the variables
-                        for (int k = 0; k <= variableCount; k++) {
-                            // Check if the variable name matches
-                            if (variables[k].name == *(it + 3)) {
-                                // Set the undeclared flag to false
-                                undeclared = false;
-                                // Set the value of the variable to the comparison
-                                variables[k].value = (variables[i].value < variables[j].value);
-                                break;
-                            }
-                        }
-                    }
-                }
-            }
-        }
+    string a = *(it + 1), b = *(it + 2), c = *(it + 3);
+    if (isInteger(b)) {
+        variables[c] = (variables[a] < atoi(b.c_str()));
     }
-    // If the variable is undeclared
-    if (undeclared) {
-        // Print an error message
-        cerr << "[Error] Variable undeclared." << endl;
+    else if (isInteger(a)){
+        variables[c] = (atoi(a.c_str()) < variables[b]);
+    }
+    else {
+        variables[c] = (variables[a] < variables[b]);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/loop.hpp b/src/identifiers/loop.hpp
index 4299e90..51c5d4f 100644
--- a/src/identifiers/loop.hpp
+++ b/src/identifiers/loop.hpp
@@ -3,29 +3,16 @@
  * By lemonorangeapple
 **/
 void loop(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is declared
-    bool undeclared = true;
-    for (int i = 0; i <= variableCount; i++) {
-        if (variables[i].name == *(it + 1)) {
-            undeclared = false;
-            // Push the variable name to the loop variable name vector
-            loopVariableName.push(string(*(it + 1)));
-            // Check if the variable is assigned
-            if (variables[i].value == 0) {
-                // Push false to the loop flag vector
-                loopFlag.push(false);
-            }
-            else {
-                // Push the current line number to the loop line vector
-                loopLine.push(int(file.tellg()) - 2);
-                // Push true to the loop flag vector
-                loopFlag.push(true);
-            }
-            break;
-        }
+    string next = *(it + 1);
+    loopVariableName.push(next);
+    if (variables[next] == 0) {
+        // Push false to the loop flag vector
+        loopFlag.push(false);
     }
-    // If the variable is undeclared, throw an error
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else {
+        // Push the current line number to the loop line vector
+        loopLine.push(int(file.tellg()) - 2);
+        // Push true to the loop flag vector
+        loopFlag.push(true);
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/multiplication.hpp b/src/identifiers/multiplication.hpp
index 6ee50a0..728946f 100644
--- a/src/identifiers/multiplication.hpp
+++ b/src/identifiers/multiplication.hpp
@@ -3,37 +3,12 @@
  * By lemonorangeapple
 **/
 void multiplication(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through the variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable is the same as the one in the expression
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // If it is, set undeclared to false and multiply the value
-                undeclared = false;
-                variables[i].value *= atoi((*(it + 2)).c_str());
-                break;
-            }
-            // If it isn't, check if the value is a variable
-            else {
-                // If it is, set undeclared to true and loop through the variables
-                undeclared = true;
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable is the same as the one in the expression
-                    if (variables[j].name == *(it + 2)) {
-                        // If it is, set undeclared to false and multiply the value
-                        undeclared = false;
-                        variables[i].value *= variables[j].value;
-                        break;
-                    }
-                }
-            }
-        }
+    string next = *(it + 2);
+    string _this = *(it + 1);
+    if (isInteger(next)) {
+        variables[_this] *= atoi((next).c_str());
     }
-    // If the variable is undeclared, print an error message
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else {
+        variables[_this] *= variables[next];
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/new.hpp b/src/identifiers/new.hpp
deleted file mode 100644
index d8c24a7..0000000
--- a/src/identifiers/new.hpp
+++ /dev/null
@@ -1,8 +0,0 @@
-/**
- * New function
- * By lemonorangeapple
-**/
-void _new(vector<string>::iterator it, ifstream &file) {
-    // Get the name of the variable
-    variables[variableCount++].name = *(it + 1);
-}
\ No newline at end of file
diff --git a/src/identifiers/not.hpp b/src/identifiers/not.hpp
index 4349987..05a04e3 100644
--- a/src/identifiers/not.hpp
+++ b/src/identifiers/not.hpp
@@ -3,26 +3,6 @@
  * By lemonorangeapple
 **/
 void _not(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable is declared
-        if (variables[i].name == *(it + 1)) {
-            undeclared = true;
-            // Check if the variable to be negated is declared
-            for (int j = 0; j <= variableCount; j++) {
-                if (variables[j].name == *(it + 2)) {
-                    // Set the value of the variable to the opposite of the original value
-                    variables[j].value = !((bool)(variables[i].value));
-                    undeclared = false;
-                    break;
-                }
-            }
-        }
-        break;
-    }
-    // If the variable is undeclared, throw an error
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
-    }
+    string next = *(it + 1);
+    variables[next] = !(bool(variables[next]));
 }
\ No newline at end of file
diff --git a/src/identifiers/output.hpp b/src/identifiers/output.hpp
index d9eca0f..bc48a2a 100644
--- a/src/identifiers/output.hpp
+++ b/src/identifiers/output.hpp
@@ -4,32 +4,20 @@
 **/
 void output(vector<string>::iterator it, ifstream &file) {
     // Check if the next token is a variable
-    if ((*(it + 1))[0] != '"') {
-        // Check if the variable is undeclared
-        bool undeclared = true;
-        // Check if the variable is already declared
-        for (int i = 0; i <= variableCount; i++) {
-            if (variables[i].name == *(it + 1)) {
-                undeclared = false;
-                printf("%.3Lf", variables[i].value);
-                break;
-            }
-        }
-        // If the variable is undeclared, print an error message
-        if (undeclared) {
-            cerr << "[Error] Variable undeclared." << endl;
-        }
+    string _this = *(it + 1);
+    if (_this[0] != '"') {
+        cout << variables[_this];
     }
     // If the next token is a string, print the string
     else {
-        // Remove the quotation marks from the string
-        string result = string(*(it + 1)).substr(1, strlen((*(it + 1)).c_str()) - 2);
+        string result = string(_this.substr(1, strlen(_this.c_str()) - 2));
         // Replace underscores with spaces
-        for (int i = 0; i < result.size(); i++) {
+        for (int i = 0; i <= result.size(); i++) {
             if (result[i] == '_') {
-                result[i] = ' ';
+                cout << ' ';
+                continue;
             }
+            cout << result[i];
         }
-        cout << result;
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/set.hpp b/src/identifiers/set.hpp
index 1ae74eb..dd7079d 100644
--- a/src/identifiers/set.hpp
+++ b/src/identifiers/set.hpp
@@ -3,37 +3,12 @@
  * By lemonorangeapple
 **/
 void set(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is already declared
-    bool undeclared = true;
-    for (int i = 0; i <= variableCount; i++) {
-        // If the variable is already declared
-        if (variables[i].name == *(it + 1)) {
-            // If the value is an integer
-            if (isInteger(*(it + 2))) {
-                // Set the value to the integer
-                undeclared = false;
-                variables[i].value = atoi((*(it + 2)).c_str());
-                break;
-            }
-            // If the value is not an integer
-            else {
-                // Check if the value is a variable
-                undeclared = true;
-                for (int j = 0; j <= variableCount; j++) {
-                    // If the value is a variable
-                    if (variables[j].name == *(it + 2)) {
-                        // Set the value to the variable
-                        undeclared = false;
-                        variables[i].value = variables[j].value;
-                        break;
-                    }
-                }
-            }
-        }
+    string next = *(it + 2);
+    string _this = *(it + 1);
+    if (isInteger(next)) {
+        variables[_this] = atoi((next).c_str());
     }
-    // If the variable is undeclared
-    if (undeclared) {
-        // Print an error message
-        cerr << "[Error] Variable undeclared." << endl;
+    else {
+        variables[_this] = variables[next];
     }
 }
\ No newline at end of file
diff --git a/src/identifiers/subtraction.hpp b/src/identifiers/subtraction.hpp
index e1079b5..31e84b3 100644
--- a/src/identifiers/subtraction.hpp
+++ b/src/identifiers/subtraction.hpp
@@ -3,37 +3,12 @@
  * By lemonorangeapple
 **/
 void subtraction(vector<string>::iterator it, ifstream &file) {
-    // Check if the variable is undeclared
-    bool undeclared = true;
-    // Loop through all variables
-    for (int i = 0; i <= variableCount; i++) {
-        // Check if the variable name matches the one in the expression
-        if (variables[i].name == *(it + 1)) {
-            // Check if the value is an integer
-            if (isInteger(*(it + 2))) {
-                // If it is, set undeclared to false and subtract the value
-                undeclared = false;
-                variables[i].value -= atoi((*(it + 2)).c_str());
-                break;
-            }
-            // If it isn't, check if the value is a variable
-            else {
-                // If it is, set undeclared to true and loop through all variables
-                undeclared = true;
-                for (int j = 0; j <= variableCount; j++) {
-                    // Check if the variable name matches the one in the expression
-                    if (variables[j].name == *(it + 2)) {
-                        // If it does, set undeclared to false and subtract the value
-                        undeclared = false;
-                        variables[i].value -= variables[j].value;
-                        break;
-                    }
-                }
-            }
-        }
+    string next = *(it + 2);
+    string _this = *(it + 1);
+    if (isInteger(next)) {
+        variables[_this] -= atoi((next).c_str());
     }
-    // If the variable is undeclared, print an error
-    if (undeclared) {
-        cerr << "[Error] Variable undeclared." << endl;
+    else {
+        variables[_this] -= variables[next];
     }
 }
diff --git a/src/init.hpp b/src/init.hpp
index f741f4a..929f061 100644
--- a/src/init.hpp
+++ b/src/init.hpp
@@ -1,5 +1,5 @@
 /**
- * Entry function of the program
+ * Init function of the program
  * By lemonorangeapple
 **/
 #include <iostream>
@@ -12,17 +12,13 @@
 #include <stack>
 #include <cmath>
 #include <condition_variable>
+#include <functional>
 using namespace std;
 #pragma GCC std("c++11")
 // Version of the program
 const string _VERSION_ = "b1.15.00";
 // Buffer size
 const int _BUFFER_SIZE_ = 1024;
-// Variable struct
-struct Variable {
-    long double value;
-    string name;
-};
 // split function
 vector<string> split(string str, char delim) {
     stringstream ss(str);
@@ -48,9 +44,7 @@ bool isInteger(string x) {
 }
 // Const variables
 char buffer[_BUFFER_SIZE_];
-Variable variables[_BUFFER_SIZE_];
 stack<bool> ifFlag;
 stack<bool> loopFlag;
 stack<string> loopVariableName;
-stack<streampos> loopLine;
-int variableCount = 0;
\ No newline at end of file
+stack<streampos> loopLine;
\ No newline at end of file
diff --git a/src/interpreter.hpp b/src/interpreter.hpp
index e251bfa..388351c 100644
--- a/src/interpreter.hpp
+++ b/src/interpreter.hpp
@@ -1,3 +1,7 @@
+/**
+ * Interpreter function of the program
+ * By lemonorangeapple
+**/
 void interpreter(vector<string> vec, ifstream &file) {
     // Read identifiers.
     for (vector<string>::iterator it = vec.begin(); it != vec.end(); ++it) {
diff --git a/src/main.cpp b/src/main.cpp
index 8c9c627..01f2cf1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4,13 +4,13 @@
 **/
 #include "init.hpp"
 map <string, void (*)(vector<string>::iterator, ifstream &)> identifiers;
+map <string, long double> variables;
 #include "identifiers/identifiers.hpp"
 #include "read.hpp"
 #include "update.hpp"
 void load() {
     identifiers["output"] = output;
     identifiers["wrap"] = wrap;
-    identifiers["new"] = _new;
     identifiers["set"] = set;
     identifiers["input"] = input;
     identifiers["addition"] = addition;
@@ -20,13 +20,13 @@ void load() {
     identifiers["equal"] = equal;
     identifiers["greater"] = _greater;
     identifiers["less"] = _less;
-    identifiers["equal_or_greater"] = equal_or_greater;
-    identifiers["equal_or_less"] = equal_or_less;
+    identifiers["equal-or-greater"] = equal_or_greater;
+    identifiers["equal-or-less"] = equal_or_less;
     identifiers["not"] = _not;
     identifiers["if"] = _if;
-    identifiers["end_if"] = end_if;
+    identifiers["end-if"] = end_if;
     identifiers["loop"] = loop;
-    identifiers["end_loop"] = end_loop;
+    identifiers["end-loop"] = end_loop;
     identifiers["note"] = note;
 }
 int main(int argc, char* argv[]) {
diff --git a/src/read.hpp b/src/read.hpp
index c15ee33..28f987a 100644
--- a/src/read.hpp
+++ b/src/read.hpp
@@ -1,3 +1,7 @@
+/**
+ * Read code function
+ * By lemonorangeapple
+**/
 #include "interpreter.hpp"
 // Read from file.
 void read(char* argv[]) {
diff --git a/src/update.hpp b/src/update.hpp
index 9957e01..490b9cf 100644
--- a/src/update.hpp
+++ b/src/update.hpp
@@ -30,7 +30,7 @@ void update() {
     string result = execute("curl -s https://junlang.imjcj.eu.org/VERSION_DEVE");
     result = result.substr(49);
     // compare version number with _VERSION_
-    if (result != _VERSION_ + '\n') {
+    if (result != _VERSION_) {
         cout << "Warning: Please update: \"https://junlang.imjcj.eu.org\"" << endl;
     }
     return;
diff --git a/tests/test1/ioput.txt b/tests/test1/ioput.txt
new file mode 100644
index 0000000..fd3f1bf
--- /dev/null
+++ b/tests/test1/ioput.txt
@@ -0,0 +1,15 @@
+Hello world!Hello world!
+Hello world!5010
+155 6
+112
+12 2
+10
+1
+2
+3
+4
+5
+6
+7
+8
+9
diff --git a/tests/test1/test.jun b/tests/test1/test.jun
new file mode 100644
index 0000000..47ccf7d
--- /dev/null
+++ b/tests/test1/test.jun
@@ -0,0 +1,31 @@
+output "Hello_world!"
+output "Hello_world!"
+wrap
+output "Hello_world!"
+set a 50
+set a 50
+output a
+input a
+addition a 5
+output a
+input a
+input b
+addition a b
+output a
+input a
+equal a 2 b
+output b
+input a
+input b
+equal a b c
+if c
+output "1"
+end-if
+set a 0
+set b 1
+loop b
+output a
+wrap
+addition a 1
+less a 10 b
+end-loop