C计算字符串中包含某个字符的个数(不区分大小写)

#include<iostream>
#include<string.h>

using namespace std;

int main(){
    string s;
    char ss;
    int count=0;
    cin>>s>>ss;
    int len = s.length();
    for(int i = 0;i < len;i++){
        if(ss>='a' && ss<='z'){
            if(s[i]==ss || s[i]==ss-32)
                count++;
        }else if(ss>='A' && ss<='Z'){
            if(s[i]==ss || s[i]==ss+32)
                count++;
        }            
    }
    cout<<count<<endl;
    return 0;
}