I've searched the standard but didn't notice the mentioned part.
我搜索了标准,但没有注意到上面提到的部分。
Is it just "anything but 0" and 1 or it is compiler-dependent?
它只是“除了0之外的任何东西”和1还是依赖于编译器的?
2 个解决方案
#1
23
The result of the logical negation operator
!is 0 if the value of its operand compares unequal to 0, 1 if the value of its operand compares equal to 0. The result has typeint.逻辑否定运算符的结果!如果其操作数的值比较不等于0则为0;如果其操作数的值比较等于0则为1.结果的类型为int。
Appears in C89/C90, C99, and C11.
出现在C89 / C90,C99和C11中。
#2
4
As hobbs said in his answer, section 6.5.3.3.5 of the C standard states that !0 evaluates to 1.
正如霍布斯在他的回答中所说,C标准的第6.5.3.3.5节规定!0评估为1。
Additionally, this behavior can be used to normalize an integer to a boolean value (i.e. either 0 or 1) with the expression !!x.
此外,此行为可用于将整数规范化为具有表达式!! x的布尔值(即0或1)。
- When
x=0,!!x=!!0=!1=0. - When
x!=0,!x=0, so!!x=!0=1.
当x = 0时,!! x = !! 0 =!1 = 0。
当x!= 0时,!x = 0,所以!! x =!0 = 1。
#1
23
The result of the logical negation operator
!is 0 if the value of its operand compares unequal to 0, 1 if the value of its operand compares equal to 0. The result has typeint.逻辑否定运算符的结果!如果其操作数的值比较不等于0则为0;如果其操作数的值比较等于0则为1.结果的类型为int。
Appears in C89/C90, C99, and C11.
出现在C89 / C90,C99和C11中。
#2
4
As hobbs said in his answer, section 6.5.3.3.5 of the C standard states that !0 evaluates to 1.
正如霍布斯在他的回答中所说,C标准的第6.5.3.3.5节规定!0评估为1。
Additionally, this behavior can be used to normalize an integer to a boolean value (i.e. either 0 or 1) with the expression !!x.
此外,此行为可用于将整数规范化为具有表达式!! x的布尔值(即0或1)。
- When
x=0,!!x=!!0=!1=0. - When
x!=0,!x=0, so!!x=!0=1.
当x = 0时,!! x = !! 0 =!1 = 0。
当x!= 0时,!x = 0,所以!! x =!0 = 1。