C语言编程：【样例输入】 abcdef def aaa 【样例输出】 please input 3 strings as MainStr , SubStr1 and SubStr2 MainStr =:6,a,b,c,d,e,f, SubStr1 =:3,d,e,f, SubStr2 =:3,a,a,a, SubStr1 compare with SubStr2 is 1 pos of SubStr1 in MainStr is 4 pos of SubStr2 in MainStr

这是一个字符串匹配的问题，需要编写 C 语言程序。下面是代码示例：

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

int main() {
    char MainStr[100], SubStr1[100], SubStr2[100];
    int i, j, len1, len2, len3, pos1 = -1, pos2 = -1, flag = 0;

    printf("please input 3 strings as MainStr , SubStr1 and SubStr2\n");
    scanf("%s%s%s", MainStr, SubStr1, SubStr2);

    len1 = strlen(MainStr);
    len2 = strlen(SubStr1);
    len3 = strlen(SubStr2);

    printf("MainStr =:%d,", len1);
    for (i = 0; i < len1; i++) {
        printf("%c,", MainStr[i]);
    }
    printf("  SubStr1 =:%d,", len2);
    for (i = 0; i < len2; i++) {
        printf("%c,", SubStr1[i]);
    }
    printf("  SubStr2 =:%d,", len3);
    for (i = 0; i < len3; i++) {
        printf("%c,", SubStr2[i]);
    }
    printf("\n");

    for (i = 0; i <= len1 - len2; i++) {
        flag = 1;
        for (j = 0; j < len2; j++) {
            if (MainStr[i+j] != SubStr1[j]) {
                flag = 0;
                break;
            }
        }
        if (flag == 1) {
            pos1 = i + 1;
            break;
        }
    }

    flag = 0;
    for (i = 0; i <= len1 - len3; i++) {
        flag = 1;
        for (j = 0; j < len3; j++) {
            if (MainStr[i+j] != SubStr2[j]) {
                flag = 0;
                break;
            }
        }
        if (flag == 1) {
            pos2 = i + 1;
            break;
        }
    }

    if (strcmp(SubStr1, SubStr2) == 0) {
        printf("SubStr1 compare with SubStr2 is 1\n");
    } else {
        printf("SubStr1 compare with SubStr2 is 0\n");
    }

    if (pos1 != -1) {
        printf("pos of SubStr1 in MainStr is %d\n", pos1);
    } else {
        printf("SubStr1 not found in MainStr\n");
    }

    if (pos2 != -1) {
        printf("pos of SubStr2 in MainStr is %d\n", pos2);
    } else {
        printf("SubStr2 not found in MainStr\n");
    }

    return 0;
}

程序实现了对三个字符串的输入，输出三个字符串的长度和内容。然后分别在 MainStr 中查找 SubStr1 和 SubStr2，输出它们在 MainStr 中的位置或者未找到的提示。最后比较 SubStr1 和 SubStr2 是否相同，输出比较结果。