c - 我们如何得到以下输出？

Question

#include <stdio.h>

int main(void)
{ 
    int i = 258;
    char ch = i;
    printf("%d", ch)
}

输出是2!

变量的范围如何工作？ c语言中不同数据类型的范围是多少？

Answer 1

当分配给较小的类型时，该值为

• 截断，即258 % 256(如果新类型无符号)
• 如果新类型已签名，则以实现定义的方式进行修改

Otherwise, if the new type is unsigned, the value is converted by repeatedly adding or subtracting one more than the maximum value that can be represented in the new type until the value is in the range of the new type.

Otherwise, the new type is signed and the value cannot be represented in it; either the result is implementation-defined or an implementation-defined signal is raised.

所以所有那些花哨的“加法或减法”意味着它的分配就像你说的:

ch = i % 256;