Stringplus/s21_sscanf.c at develop · Orurh/Stringplus · GitHub

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#include "s21_string.h"

int s21_sscanf(const char *str, const char *format, ...) {
  if (!str || !format) return -1;
  const char *string = str;
  const char *start = str;
  FormatParser parser = {.format = format};
  int result = 0;
  int continue_parsing = 1;
  va_list args;
  va_start(args, format);
  while (continue_parsing) {
    if (!parse_format(&parser)) {
      continue_parsing = 0;
    } else if ((!string || *string == '\0') && parser.specifier != 'n') {
      continue_parsing = 0;
    } else {
      switch (parser.specifier) {
        case '%':
          string++;
          break;
        case 'u':
        case 'd':
        case 'X':
        case 'x':
        case 'i':
        case 'o':
          string = dScanSpecifier(string, args, &parser, &result);
          break;
        case 'c':
          string = cScanSpecifier(string, args, &parser, &result);
          break;
        case 's':
          string = sScanSpecifier(string, args, &parser, &result);
          break;
        case 'g':
        case 'G':
        case 'f':
        case 'e':
        case 'E':
          string = fScanSpecifier(string, args, &parser, &result);
          break;
        case 'p':
          string = pScanSpecifier(string, args, &parser, &result);
          break;
        case 'n':
          string = nScanSpecifier(string, args, start);
          break;
      }
    }
  }
  va_end(args);
  while (*string == ' ' || *string == '\t') string++;
  result = (result > 0 || s21_strlen(string) != 0) ? result : -1;
  return result;
}

bool parse_format(FormatParser *parser) {
  bool success = true;
  while ((*parser->format == ' ') || (*parser->format == '\t'))
    parser->format++;
  if (*parser->format == '\0') success = false;
  if (success && *parser->format != '%') success = false;
  if (success) {
    parser->format++;
    parser->suppress = (*parser->format == '*');
    if (parser->suppress) parser->format++;
    parser->width = 0;
    while (s21_isdigit(*parser->format)) {
      parser->width = parser->width * 10 + (*parser->format - '0');
      parser->format++;
    }
    parser->length = '\0';
    if (*parser->format == 'h' || *parser->format == 'l' ||
        *parser->format == 'L') {
      parser->length = *parser->format;
      parser->format++;
    }
    if (*parser->format != '\0') {
      parser->specifier = *parser->format;
      parser->format++;
    }
  }
  return success;
}