如果条件为单和(&) [英] If condition with single and (&)

问题描述

我们都知道&&(double和)for和condition.单个以及内部发生什么情况如何执行条件.

We all know && (double and) for and condition. for single and What happen internally how condition gets executed.

 if(true & bSuccess)
{
}

推荐答案

true & bSuccess

在此表达式中，两个操作数都提升为 int ，然后对& 求值.如果bSuccess为true，则您将获得 1&1 ，即 1 (或 true ).如果bSuccess为false，您将得到 1&0 ，即 0 (或 false )

in this expression both operands are promoted to int and then & is evaluated. If bSuccess is true you will get 1 & 1 which is 1 (or true). If bSuccess is false you'll get 1 & 0 which is 0 (or false)

因此，在布尔值的情况下，&& 和& 始终会产生相同的结果，但在&中并不完全等效; 将始终同时评估其参数，并且如果第一个参数为false，则& 不会评估其第二个参数.

So, in case of boolean values && and & will always yield the same result, but they are not totally equivalent in that & will always evaluate both its arguments and && will not evaluate its second argument if the first one is false.

示例:

bool f() { std::cout << "f"; return false; }
bool g() { std::cout << "g"; return true; }

int main()
{
    f() && g(); //prints f. Yields false
    f() & g();  //prints fg or gf (unspecified). Yields 0 (false)
}

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