如何将C++中bool值输出的1/0改为true/false？

我完成了一项作业，现在程序里输出bool类型时会显示1或0，想要改成输出true或false。这是个多文件程序，以下是当前的输出示例和main.cpp代码，求修改建议。

当前输出 #

1 = true, 0 = false
------------
c1 >= c2 : 1
c1 <= c2 : 0
c1 != c2 : 1
c1 < c2 : 0
c1 > c2 : 1
c1 == c2 : 0

现有main.cpp代码 #

int main() 
{
    // 声明两个圆的半径用于比较
    Circle c1(7);
    Circle c2(6);

    // 输出布尔值（当前显示1或0）
    bool compare;
    cout << "1 = true, 0 = false" << endl;
    cout << "------------" << endl;

    compare = c1 >= c2;
    cout<< "c1 >= c2 : "<< compare << endl;

    compare = c1 <= c2;
    cout<< "c1 <= c2 : "<< compare << endl;

    compare = c1 != c2;
    cout << "c1 != c2 : " << compare << endl;

    compare = c1 < c2;
    cout<< "c1 < c2 : " << compare << endl;

    compare = c1 > c2;
    cout << "c1 > c2 : " << compare << endl;

    compare = c1 == c2;
    cout << "c1 == c2 : " << compare << endl;
    cout << endl;
}

方法1：使用std::boolalpha（推荐） #

C++标准库自带的std::boolalpha操纵符可以直接让cout输出bool类型时显示true或false，只需要在输出布尔值前添加一行代码：

cout << boolalpha;

修改后的完整main.cpp代码：

#include <iostream>
using namespace std;

int main() 
{
    Circle c1(7);
    Circle c2(6);

    bool compare;
    cout << boolalpha; // 启用bool值的文本输出模式
    cout << "true = 真, false = 假" << endl;
    cout << "------------" << endl;

    compare = c1 >= c2;
    cout<< "c1 >= c2 : "<< compare << endl;

    compare = c1 <= c2;
    cout<< "c1 <= c2 : "<< compare << endl;

    compare = c1 != c2;
    cout << "c1 != c2 : " << compare << endl;

    compare = c1 < c2;
    cout<< "c1 < c2 : " << compare << endl;

    compare = c1 > c2;
    cout << "c1 > c2 : " << compare << endl;

    compare = c1 == c2;
    cout << "c1 == c2 : " << compare << endl;
    cout << endl;
}

如果之后需要恢复默认的1/0输出，用cout << noboolalpha;即可。

方法2：三元运算符手动输出 #

不想用标准库操纵符的话，输出时直接用三元运算符判断并输出对应字符串：

cout<< "c1 >= c2 : "<< (compare ? "true" : "false") << endl;

修改后的输出行示例：

compare = c1 >= c2;
cout<< "c1 >= c2 : "<< (compare ? "true" : "false") << endl;

compare = c1 <= c2;
cout<< "c1 <= c2 : "<< (compare ? "true" : "false") << endl;

// 其余输出行按同样方式修改

方法3：封装辅助函数 #

如果多处需要输出bool的文本形式，封装一个小函数更方便：

const char* boolToString(bool value) {
    return value ? "true" : "false";
}

输出时调用该函数：

cout<< "c1 >= c2 : "<< boolToString(compare) << endl;

内容的提问来源于stack exchange，提问作者user20544996