计算某字母出现的次数

ABCabc
A
2

/*由于不清楚C++字符串类的大小写转换的函数，只能将要比较的字符进行了转换*/
#include<iostream>
#include<string>

using namespace std;

int main() {
    string input;
    char target;
    getline(cin, input);
    cin >> target;
    char target1;
    //if (target >= 'a' && target <= 'z')
    if (target >= 65 && target <= 90)
        target1 = target + 32;
    else if (target >= 97 && target <= 122)
        target1 = target - 32;
    else target1 = target;
    int count = 0;
    for (int i = 0; i < input.size(); ++i) {
        if (input[i] == target || input[i] == target1)
            count++;
    }
    cout << count << endl;
    return 0;
}

注意针对两行输入问题时的处理方案，外部调试，getline处理字符串，char型字符直接cin或者cin.get()