C-为什么char c = 129会转换为-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，则由于二进制等效项，它会转换为 -128 。 code> 10000000首位指示符号）。
129 的二进制等价项是 10000001 ，它将转换为什么值？

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

Thanks, S

推荐答案

负数存储为该数字的正数的2的补码。

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，将130分配为-126。

Similarly, 130 will be assigned as -126.

谢谢！

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