[개발/C++] 문자열 치환/변환

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

char *replaceAll(char *s, const char *olds, const char *news);

void main(void){

  char s[] = "봉숭아 학당! 봉숭아 학당! 봉숭아 학당! 봉숭아 학당!";

  char *s2;

  printf("원본: %s\n", s);

  s2 = replaceAll(s, "봉숭아", "맹구");

  // 에러가 있으면 NULL 을 리턴. 에러가 없으면 결과 출력

  (s2 != NULL) ? printf("치환: %s\n", s2) : fputs("Replace String Error...\n", stderr);

}

char *replaceAll(char *s, const char *olds, const char *news) {

  char *result, *sr;

  size_t i, count = 0;

  size_t oldlen = strlen(olds); if (oldlen < 1) return s;

  size_t newlen = strlen(news);

  if (newlen != oldlen) {

    for (i = 0; s[i] != '\0';) {

      if (memcmp(&s[i], olds, oldlen) == 0) count++, i += oldlen;

      else i++;

    }

  } else i = strlen(s);

  result = (char *) malloc(i + 1 + count * (newlen - oldlen));

  if (result == NULL) return NULL;

  sr = result;

  while (*s) {

    if (memcmp(s, olds, oldlen) == 0) {

      memcpy(sr, news, newlen);

      sr += newlen;

      s  += oldlen;

    } else *sr++ = *s++;

  }

  *sr = '\0';

  return result;

}


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