C++读取文件内容替换和插入字符串

以下是一个C程序示例，用于读取文件内容并替换和插入字符串：

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

#define MAX_LINE_LENGTH 1024

void replaceString(char *line, const char *search, const char *replace) {
    char *match = strstr(line, search);
    if (match != NULL) {
        size_t searchLen = strlen(search);
        size_t replaceLen = strlen(replace);
        size_t tailLen = strlen(match + searchLen);
        memmove(match + replaceLen, match + searchLen, tailLen + 1);
        memcpy(match, replace, replaceLen);
    }
}

int main() {
    FILE *fp;
    char *line = NULL;
    size_t len = 0;
    ssize_t read;

    const char *filename = "file.txt";
    const char *searchString = "hello";
    const char *replaceString = "goodbye";
    const char *insertString = "world";

    fp = fopen(filename, "r");
    if (fp == NULL) {
        printf("Error: could not open file '%s'\n", filename);
        return 1;
    }

    while ((read = getline(&line, &len, fp)) != -1) {
        replaceString(line, searchString, replaceString);
        printf("%s", line);
    }

    fclose(fp);
    if (line) {
        free(line);
    }

    fp = fopen(filename, "a");
    if (fp == NULL) {
        printf("Error: could not open file '%s'\n", filename);
        return 1;
    }

    fprintf(fp, "%s\n", insertString);

    fclose(fp);
    return 0;
}

这个程序打开名为“file.txt”的文件并读取每一行。它用“replaceString”函数替换每一行中的“hello”字符串为“goodbye”字符串。然后，它输出每一行到标准输出。接下来，它打开文件以追加模式写入“world”字符串。最后，它关闭文件并返回0以表示成功运行程序。