题解 | #计算某字符出现次数#

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

string lower(string str)//构造一个函数使输入字符串统一为小写
{       
    for(int i = 0; i < str.size(); i++){
        if(str[i] >= 'A' && str[i] <= 'Z'){
            str[i] = str[i] + 32;       //大小写字母之间ASCII码差值为32
        }
    }

    return str;
}

int main() {
    string str;
    getline(cin, str);
    char target;
    cin >> target;
    str = lower(str);
    if(target >= 'A' && target <= 'Z'){
        target = target + 32;
    }
    int count = 0;
    for(int i = 0; i < str.size(); i++){
        if(str[i] == target){
            count++;
        }
    }
    cout << count << endl;
  
    return 0;
}