许多编译器似乎只保留0或1的布尔值,但我不知道这将始终工作:
int类型的= 2;布尔B = A;INT C = 3 + B; // 4或5?解决方案
是:
在C ++(§4.5/ 4):
bool类型的右值可 转换成int类型的右值, 以虚假成为零和真 成为一体。
在C,当值转换为 _Bool ,就变成0或1(§6.3.1.2/ 1):
当任何标值被转换为 _Bool,结果是0,如果值进行比较等于0;否则, 结果是1。
当转换为 INT ,这是pretty直线前进。 INT 可容纳0和1,所以有一个在价值没有改变(§6.3.1.3)。
Many compilers seem to be keeping only 0 or 1 in bool values, but I'm not sure this will always work:
int a = 2; bool b = a; int c = 3 + b; // 4 or 5?解决方案
Yes:
In C++ (§4.5/4):
An rvalue of type bool can be converted to an rvalue of type int, with false becoming zero and true becoming one.
In C, when a value is converted to _Bool, it becomes 0 or 1 (§6.3.1.2/1):
When any scalar value is converted to _Bool, the result is 0 if the value compares equal to 0; otherwise, the result is 1.
When converting to int, it's pretty straight-forward. int can hold 0 and 1, so there's no change in value (§6.3.1.3).
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是C / C ++布尔类型始终保证typecast'ed为int时为0或1?
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