这是一道C++程序问题，希望大家解答？

Question

下面的函数统计子字符串substr在字符串str中出现的次数

int str_count(char* substr, char* str)
{
    int count = 0;
    int n=0,m=0;
    while (*substr) {
        n++;
        substr++;
    }
    while (*str)
    {
        m++;
        str++;
    }
    int j = 0;
    for (int i = 0; i < m; i++)
    {
        if (j == n-1) {
            count++; j = 0;
        }
        if (str[i] == substr[j])
        {
            j++;
        }
        else if(j==n-1||str[i]!=substr[j])
        {
            j = 0;
            //continue;
        }
        
        
    }
    return count;
}
int main()
{
    char s1[5] = "god";
    char  s[20] = "lagodgodogod";
    cout <<str_count(s1, s);
    return 0;
}

我主函数这个用例一直不对，输出一直是4不知道哪里写错了

Answer 1

你两个指针都移动到指向'\0'了，应重新指向第一个字符

#include<iostream>

using namespace std;

int str_count(char* substr, char* str)
{
    int count = 0;
    int n=0,m=0;
    while (*substr) {
        n++;
        substr++;
    }
    substr-=n;
    while (*str)
    {
        m++;
        str++;
    }
    str-=m;
    int j = 0;
    for (int i = 0; i < m; i++)
    {
        if (str[i] == substr[j])
        {
            j++;
            if (j == n) {
                count++;
                j = 0;
            }
        }
        else
        {
            j = 0;
        }
        
    }
    return count;
}
int main()
{
    char s1[5] = "god";
    char  s[20] = "lagodgodogod";
    cout <<str_count(s1, s);
    return 0;
}