int和焦炭的实际差别 [英] Practical difference between int and char

问题描述

我来分析这些code片段的输出：

I have to analyse the output of these code fragments:

int x, y;
x = 200; y = 100;
x = x+y; y = x-y; x = x-y;
printf ("%d %d\n", x, y);

char x, y;
x = 200; y = 100;
x = x+y; y = x-y; x = x-y;
printf ("%d %d\n", x, y);

所以，我现在知道 INT 为整数，字符字符;我读过有关的区别，如果我把在的printf 的％d个，它的形式返回数字和％C ，在字符的形式。

So, I know now that int stands for integer and char for character; I've read about the differences and if I put in the printf the %d, it returns in the form of digits, and %c, in the form of a character.

ASCII字符code为'A' 65为例，但为什么第二个函数打印 100 -56 ， 100 200 ？

The ASCII character code for 'A' is 65 for example, but why does the second function print 100 -56, instead of 100 200?

推荐答案

在问题中所使用的平台，键入字符好像是1字节（8位）大小是有符号类型与1符号位和7位值（使用2的补码运算）。它存储从-128到127值，因此，这是发生了什么 X 和是：

On the platform used in the question, the type char seems to be 1 byte (8 bits) size and is a signed type with 1 sign bit and 7 value bits (and using 2's complement arithmetic). It stores values from -128 to 127. So, this is what's happening to x and y:

x = 200 => x takes value -56
y = 100 => y takes value 100
x = x+y => x takes value 44
y = x-y => y takes value -56
x = x-y => x takes value 100

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