C++ If语句将不起作用

Question

//Writing a letter

#include <iostream>
using namespace std;

int main() {
string first_name;      //Name of addressee
string friend_name;     //Name of a friend top be mentioned in the letter
char friend_sex, m, f;  //variable for gender of friend

friend_sex = 0;

cout << "\nEnter the name of the person you want to write to: ";
cin >> first_name;

cout << "Enter the name of a friend: ";
cin >> friend_name;

cout << "Enter friend's sex(m/f): ";    //Enter m or f for friend
cin >> friend_sex;                      //Place m or f into friend_sex

cout << "\nDear " << first_name << ",\n\n"
     << "   How are you? I am fine. I miss you!blahhhhhhhhhhhhhhhh.\n"   
     << "blahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.\n"
     << "Have you seen " << friend_name << " lately? ";

//braces only necessary if there are more than one statement in the if function
if(friend_sex == m) {
    cout << "If you see " << friend_name << ", please ask him to call me.";             
}   //If friend is male, output this
if(friend_sex == f) {
    cout << "If you see " << friend_name << ", please ask her to call me.";
}   //If friend is female, output this

return(0);
}

实际结果是这样的:

Enter the name of the person you want to write to: MOM

Enter the name of a friend: DAD

Enter friend's sex(m/f): m

Dear MOM, 

        How are you? I am fine. I miss you! blahhhhhhhhhhhhhhhhh.
        blahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.
        Have you seen DAD lately?

这个程序正在模拟一封简短的信件。输出一个单词 block 很容易，但是当我想在字母中放置一些条件时，我就遇到了麻烦。即使我在程序询问我时输入了 friend_sex (m/f)，if 语句的输出也没有实现。为什么？

Answer 1

您正在针对未初始化的字符变量 m 测试 friend_sex。您可能想要针对文字值 'm' 进行测试。这就像有一个名为 seven 的整数变量，并期望它保存值 7。