使用C替换文本文件中的行

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BUFFER_SIZE 1024

// 替换文本文件中的行
int replace_lines(char *filename, char *new_content) {
  FILE *file = fopen(filename, "r");
  if (!file) {
    return 1;
  }

  char buffer[BUFFER_SIZE];
  size_t read_size = 0;
  while ((read_size = fread(buffer, 1, BUFFER_SIZE, file)) > 0) {
    // 将旧行读取到内存中
    char *old_lines = malloc(read_size);
    if (!old_lines) {
      fclose(file);
      return 1;
    }
    memcpy(old_lines, buffer, read_size);

    // 替换内容
    char *new_line = str_replace(old_lines, "\n", new_content);
    if (!new_line) {
      free(old_lines);
      fclose(file);
      return 1;
    }

    // 写入新文件
    FILE *new_file = fopen(filename, "w");
    if (!new_file) {
      free(old_lines);
      fclose(file);
      return 1;
    }
    fwrite(new_line, 1, strlen(new_line), new_file);
    free(old_lines);
    fclose(new_file);
  }
  fclose(file);
  return 0;
}

int main() {
  char *filename = "file.txt";
  char *new_content = "This is the new content";

  int status = replace_lines(filename, new_content);
  if (status == 0) {
    printf("替换成功。\n");
  } else {
    printf("替换失败。\n");
  }

  return 0;
}