用c语言写串的增、删、改、查简单代码

以下是一个简单的串操作的C语言代码：

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

#define MAXLEN 50

typedef struct {
    char str[MAXLEN+1];  // 存储串的数组
    int len;             // 串的长度
} String;

// 初始化串
void InitString(String *s, char *str) {
    int len = strlen(str);
    if (len > MAXLEN) {
        printf("Error: string is too long\n");
        exit(1);
    }
    strcpy(s->str, str);
    s->len = len;
}

// 打印串
void PrintString(String *s) {
    printf("%s\n", s->str);
}

// 在串中插入子串
void InsertString(String *s, int pos, char *sub) {
    int sublen = strlen(sub);
    if (s->len + sublen > MAXLEN) {
        printf("Error: string is too long\n");
        exit(1);
    }
    if (pos < 1 || pos > s->len+1) {
        printf("Error: invalid position\n");
        exit(1);
    }
    // 先把pos及之后的字符后移sublen个位置
    for (int i = s->len; i >= pos; i--) {
        s->str[i+sublen] = s->str[i];
    }
    // 再将子串插入到pos位置
    for (int i = 0; i < sublen; i++) {
        s->str[pos+i-1] = sub[i];
    }
    s->len += sublen;
}

// 删除串中的子串
void DeleteString(String *s, int pos, int len) {
    if (pos < 1 || pos > s->len) {
        printf("Error: invalid position\n");
        exit(1);
    }
    if (len < 0 || pos+len-1 > s->len) {
        printf("Error: invalid length\n");
        exit(1);
    }
    // 先把pos+len及之后的字符前移len个位置
    for (int i = pos+len; i <= s->len; i++) {
        s->str[i-len] = s->str[i];
    }
    s->len -= len;
}

// 替换串中的子串
void ReplaceString(String *s, int pos, int len, char *sub) {
    DeleteString(s, pos, len);
    InsertString(s, pos, sub);
}

// 查找子串
int FindString(String *s, char *sub) {
    char *p = strstr(s->str, sub);
    if (p == NULL) {
        return -1;
    } else {
        return p - s->str + 1;
    }
}

int main() {
    String s;
    InitString(&s, "Hello, world!");
    PrintString(&s);

    InsertString(&s, 8, "C language ");
    PrintString(&s);

    ReplaceString(&s, 8, 9, "programming");
    PrintString(&s);

    DeleteString(&s, 8, 11);
    PrintString(&s);

    int pos = FindString(&s, "world");
    if (pos == -1) {
        printf("Not found\n");
    } else {
        printf("Found at position %d\n", pos);
    }

    return 0;
}

参考文献：[《数据结构与算法分析》（第3版）](https://book.douban.com/subject/30370902/)