提交记录 #405

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

// 函数声明
char* replaceSubstring(char* source, const char* toReplace, const char* replacement);

int main() {
    char s[101]; // 源串 s，长度<=100
    char t[11];  // 被替换串 t，长度<=10
    char str[11]; // 替换串 str，长度<=10

    // 读取源串 s
    fgets(s, sizeof(s), stdin);
    s[strcspn(s, "\n")] = '\0'; // 去除换行符

    // 读取被替换串 t
    fgets(t, sizeof(t), stdin);
    t[strcspn(t, "\n")] = '\0'; // 去除换行符

    // 读取替换串 str
    fgets(str, sizeof(str), stdin);
    str[strcspn(str, "\n")] = '\0'; // 去除换行符

    // 执行替换
    char* result = replaceSubstring(s, t, str);
    if (result) {
        printf("%s\n", result); // 输出替换后的字符串
        free(result); // 释放动态分配的内存
    } else {
        printf("替换过程中发生错误。\n");
    }

    return 0;
}

// 字符串替换函数
char* replaceSubstring(char* source, const char* toReplace, const char* replacement) {
    char *pos, *dst, *end;
    size_t toReplaceLen = strlen(toReplace);
    size_t replacementLen = strlen(replacement);
    size_t sourceLen = strlen(source);
    size_t resultLen = sourceLen; // 初始结果长度等于源长度

    // 计算结果字符串的最终长度
    for (pos = source; (pos = strstr(pos, toReplace)) != NULL; pos += toReplaceLen) {
        resultLen += replacementLen - toReplaceLen;
    }

    // 分配内存
    dst = (char*)malloc(resultLen + 1);
    if (!dst) return NULL;

    end = dst; // end 指向当前写入位置

    // 复制字符串，执行替换
    while ((pos = strstr(source, toReplace)) != NULL) {
        size_t offset = pos - source;
        memcpy(end, source, offset);
        end += offset;
        memcpy(end, replacement, replacementLen);
        end += replacementLen;
        source += offset + toReplaceLen;
    }
    strcpy(end, source); // 复制剩余的字符串

    return dst;
}