请教，，子串在母串种出现的次数

供参考：

#include <stdio.h>
int count(char* str, char* substr);
int main()
{
    char str[80], substr[80];
    int n = 0;
    gets(str);
    gets(substr);
    printf("%d\n", count(str, substr));
    return 0;
}
int count(char* str, char* substr)
{
    int i, j, k, num = 0;
    for (i = 0; str[i] != '\0'; i++)
        for (j = i, k = 0; substr[k] == str[j]; k++, j++)
            if (substr[k+1] == '\0') { num++; break; }
    return num;
}