题解 | #计算某字符出现次数#

#include <cctype>
#include <iostream>
using namespace std;

int main() {
    int sum = 0,num;
    string str;
    char ch;
    getline(cin,str);//获取字符串
    num = str.size()-1;
    cin >> ch;//获取字符
    
    while (num != -1) { 
        if(isdigit(ch)){//如果是数字直接判断
            if(str[num] == ch)
                sum += 1;
        }else if(isupper(ch)){//如果是大写转换小写一起判断
            char ch1 = tolower(ch);
            if(str[num] == ch || str[num] == ch1)
                sum += 1;
        }else{//如果是小写转换大写一起判断
            char ch1 = toupper(ch);
            if(str[num] == ch || str[num] == ch1)
                sum += 1;
        } 
        num--;
    }
    cout << sum;
    return 0;
}