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一.int型的最值
有符号
* 最小值:-2147483647-1
* 最大值:2147483647
无符号
* 最大值:0xffffffff
* 最小值:0
* 大家可以在整形类型的取值范围限制头文件中查看:limits.h
二.int型最小值的原因
当我们直接给int型变量赋-2147483648时会发生什么?
会发生错误,VS给出的原因是
事实上,当我们把最小值-2147483648赋给整形变量时,发生了两次变化
* 输入数字2147483648,因为整形的最大值为2147483647,整形变量无法接收,需要发生隐式类型转化,由int型变为unsigned int
* 在将负号赋给此时的变量,结果仍为2147483648
如果这样赋值后,结果是正确的,这会使编译器无法确认输入的值。
例如:
int a = 10 > (-2147483648);
-2147483648发生整形提升,变为正数,10跟着发生整形提升但没有改变,结果为0;
而写成-2147483647-1的形式,编译器会判断它是个负数,从而赋值
所以当我们需要使用正数的最小值时,可用如下方法:
* 使用limits.h头文件包含的宏定义名INT_MIN
* 直接使用-2147483647-1,或者-2147483646-2都可以(需要更小的数时也要用此方法)