project/Standard.java at master · UJ09/project · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
public class Standard
{
/**
 * array op[] contains operators
 */
 char[] op;
 /**
  * array o[] contains operands
  */
 double[] o;
 /**
  * Checks whether the character entered is an operator or not
  */
 private  boolean isOperator(char ch)
   {
      boolean flag=false;
      if(ch=='+' || ch=='-'||ch=='*' || ch=='/')
      flag=true;
      return(flag);
    }
    /**
     * Evaluates an expression having no brackets.
     */
    private double compute(String s)
    {
        buildArrays(s);
        return(eval());
    }

    /**
     * Stores all operators and operands in two arrays
     */
private void buildArrays(String s)
{
String s1="";
int pos=0;
int count=0;
if(s.charAt(0)=='-')
s="0"+s;
int ln=s.length();

for(int i=pos;i<s.length()-1;i++)
{
char c=s.charAt(i);
char c1=s.charAt(i+1);
if(isOperator(c)&& c1=='-')
{
i++;
count++;
    }
    else if(isOperator(c))
    count++;
    }
    op=new char[count];
    o=new double[count+1];
    for(int i=0;i<=count;i++)
    o[i]=1;

    int k=0, k1=0;
    for(int i=0;i<s.length();i++)
{
char c=s.charAt(i);
char c1=' ';
if(i<ln-1)
c1=s.charAt(i+1);

if(i<s.length()-1 && isOperator(c)==true && isOperator(c1)==false)
{
op[k]=c;
o[k]=1;
k++;
o[k1]=o[k1]*Double.parseDouble(s1);
s1="";
k1++;
    }
    else if(i<s.length()-1 && isOperator(c)==true && c1=='-')
{
op[k]=c;
k++;
o[k1]=o[k1]*Double.parseDouble(s1);
s1="-";
k1++;
i++;
    }

   else
    {
        s1=s1+c;
    }
    }
    o[count]=Double.parseDouble(s1);
    for(int i=0;i<op.length;i++)
{
if(op[i]=='-')
{
op[i]='+';
o[i+1]=-o[i+1];
    }
    }


  double res= eval();
    }

    /**
     * Evaluates the result
     */

private double eval()
{

double s=o[0];
int pos=0;
for(int i=0;i<op.length;i++)
{
if(op[i]=='*')
{o[i+1]=o[i+1]*o[i];
o[i]=0;
op[i]=' ';}
else if(op[i]=='/')
{o[i+1]=o[i]/o[i+1];
o[i]=0;
op[i]=' ';
    }
    }


    double r=0;
for(int i=0;i<op.length;i++)
{
if(op[i]=='-')
{
int j=i;
while(o[j++]==0);
o[j]=-1*o[j];

    }
}

for(int i=0;i<o.length;i++)
{r=r+o[i];}
return(r);
    }

    /**
     * Calculate: this method evaluates an expression having brackets. Only
     * first bracket is allowed. Uses the "compute" method.
     */
    public   double calculate(String str)
    {
       double res=0.0;

        int p1;
        do{
        p1=str.lastIndexOf("(");
        if(p1<0) break;
         String st=str.substring(p1+1);
        int p2=st.indexOf(")");

        String s=st.substring(0,p2);


       str=str.substring(0,p1);
       str=str+compute(s);
       str=str+st.substring(p2+1);;
       str=str.replace("+-","-");
        str=str.replace("-+","-");
         str=str.replace("--","+");

    }

        while(p1>=0);
     res=compute(str);
     return(res);
    }
    }