C-为什么char c=129会转换成-127? [英] C- why char c=129 will convert into -127?

问题描述

如果我们将 +128 分配给 char 变量，那么它会被转换为 -128 因为二进制等效(10000000-first bit tell sign).129 的二进制等价物是 10000001，它将被转换成什么值?

if we assign +128 to char variable then it is converted into -128 because of binary equivalent(10000000-first bit tells sign). Binary equivalent of 129 is 10000001, What will be the value it will be converted to?

char c=129;

char c=129;

谢谢，S

推荐答案

负数存储为该数的正数的 2 补码.

Negative numbers are stored as 2's compliment of the positive of that number.

例如:

  -127 is stored as 2's compliment of 127
    127 is 01111111 in binary
    2's compliment=(1's compliment of a number) + 1
    therefore, 2's compliment of 127(01111111) is 10000001(-127).

And 10000001 is 129:: Therefore when you give 129 to a char variable, compiler takes it as negative number 127.

同样，130 将被分配为 -126.

Similarly, 130 will be assigned as -126.

谢谢！！

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