检查子串是否在主串中，如果是，从找到的子串开始打印主串

Question

我有一个获取 2 个字符串的代码，它必须检查主字符串是否包含子字符串，如果包含，它将打印主字符串，但它将从子字符串的位置开始。例如，如果我的主字符串是“hello my name is”，而我的子字符串是“my”，它将打印“my name is”作为新的主字符串。

我有代码，它正在运行。但我很难理解它为什么起作用。谁能解释一下这个功能是如何工作的？

char *recursiveStrStr(char *str, char *substr);

尤其是这一行:

return recursiveStrStr(str + 1, substr);

这是代码:

#include <stdio.h>
#include <conio.h>

int recursiveHasPrefix(char *str, char *prefix);
char *recursiveStrStr(char *str, char *substr);

int main()
{

    char *str = "Yesterday all my troubles seemed so far away";
    char *subStr[6] = { "Yes", "all", "my", "see", "far", "day" };
    char *res;
    int i;
    printf("%s\n", str);
    res = str;
    for (i = 0; i < 6; i++)
    {
        printf("%s\n", subStr[i]);
        res = recursiveStrStr(res, subStr[i]);
        if (res == 0)
        {
            printf("The specified text is not found.\n");
            break;
        }
        else
            printf("The found text: %s\n", res);
    }
    getch();
    return 0;
}

int recursiveHasPrefix(char *str, char *prefix)
{
    if (*prefix == '\0')
        return 1;
    if (str[0] != prefix[0])
        return 0;
    return recursiveHasPrefix(str + 1, prefix + 1);

}

char *recursiveStrStr(char *str, char *substr)
{
    int check;
    if (*str == '\0' && *substr != '\0')
        return 0;

    check = recursiveHasPrefix(str, substr);
    if (check == 1)
        return str;

    return recursiveStrStr(str + 1, substr);

}

Answer 1

ABCDEFG CDEF

输出:CDEFG

Now what your program doing?

ABCDEFG CDEF ---> Is there any common prefix such that it's length=len(CDEF)=4
No so return 0

BCDEFG CDEF --> No

CDEFG CDEF --> matches ...then go to DEFG DEF ---> EFG EF --> FG F --> G . return 1.

现在你正在返回那个点并打印。