Stringplus/sscanf_conversions.c at develop · Orurh/Stringplus · GitHub

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#include "s21_string.h"

bool s21_isdigit(int c) { return c >= '0' && c <= '9'; }

long double s21_strtod(const char *string, char **endptr, int width) {
  long double result = 0.0;
  int sign = 1;
  const char *start = string;
  if (width == 0) width = 64;
  while ((*start == ' ' || *start == '\t') && width > 0) start++;
  if (width > 0 && *start == '-') {
    sign = -1;
    start++;
    width--;
  } else if (width > 0 && *start == '+') {
    start++;
    width--;
  }
  while (width > 0 && *start >= '0' && *start <= '9') {
    result = result * 10 + (*start - '0');
    start++;
    width--;
  }
  if (width > 0 && *start == '.') {
    start++;
    width--;
    long double fraction = 0.1;
    while (width > 0 && *start >= '0' && *start <= '9') {
      result += (*start - '0') * fraction;
      fraction /= 10;
      start++;
      width--;
    }
  }
  if (width > 0 && (*start == 'e' || *start == 'E')) {
    start++;
    start = s21_strtod_exponent(start, &width, &result);
  }
  if (endptr) *endptr = (char *)(start == string ? string : start);

  return result * sign;
}

const char *s21_strtod_exponent(const char *start, int *width,
                                long double *result) {
  int exp_sign = 1;
  int exponent = 0;
  if (*width > 0 && *start == '-') {
    exp_sign = -1;
    start++;
    (*width)--;
  } else if (*width > 0 && *start == '+') {
    start++;
    (*width)--;
  }
  while (*width > 0 && *start >= '0' && *start <= '9') {
    exponent = exponent * 10 + (*start - '0');
    start++;
    (*width)--;
  }
  *result *= powl(10, exp_sign * exponent);
  return start;
}

const char *s21_strtol_digits(const char *start, long long int *result,
                              int base, int *width) {
  int parsing_complete = 0;
  while (*width > 0 && *start && !parsing_complete) {
    int digit = -1;
    if (*start >= '0' && *start <= '9')
      digit = *start - '0';
    else if (*start >= 'a' && *start <= 'z')
      digit = *start - 'a' + 10;
    else if (*start >= 'A' && *start <= 'Z')
      digit = *start - 'A' + 10;
    if (digit < 0 || digit >= base) {
      parsing_complete = 1;
    } else {
      *result = (*result) * base + digit;
      start++;
      (*width)--;
    }
  }
  return start;
}

long long int s21_strtol(const char *string, char **endptr, int base, int width,
                         char specifier) {
  const char *start = string;
  long long int result = 0;
  int sign = 1;
  if (width == 0) width = 64;
  while ((*start == ' ' || *start == '\t') && width > 0) {
    start++;
  }
  if (width > 0 && *start == '-') {
    sign = -1;
    start++;
    width--;
  } else if (width > 0 && *start == '+') {
    start++;
    width--;
  }
  if (specifier == 'x' || specifier == 'X' || specifier == 'i') {
    if (*start == '0' && (*(start + 1) == 'x' || *(start + 1) == 'X')) {
      width > 1 ? (start += 2, width -= 2) : (start++, width--);
      base = 16;
    }
  }
  if (specifier == 'o' || specifier == 'i') {
    if (*start == '0' && (*(start + 1) >= '0' && *(start + 1) <= '7')) {
      start++;
      width--;
      base = 8;
    }
  }
  if (base != 16 && base != 8) base = 10;

  start = s21_strtol_digits(start, &result, base, &width);
  if (endptr) *endptr = (char *)start;
  return result * sign;
}