【c语言】有符号数据类型与无符号数据类型的计算

// 有符号数据类型与无符号数据类型的计算

#include <stdio.h>

int main()
{
char c;// -128~127
unsigned char uc;//0~255
unsigned short us;// 0~65535
c = 128;
uc = 128;
// 字符型给短整型赋值有默认的类型提升，前边八位补其符号位
us = c + uc;
// us = -128 + 128 = 0即1111 1111 1000 0000 + 0000 0000 1000 0000 = 1 0000 0000 0000 0000即0x0
printf("0x%x\n", us);
us = (unsigned char)c + uc;//c:0~255
// us = 128 + 128 = 256即0000 0000 1000 0000 + 0000 0000 1000 0000 = 0000 0001 0000 0000即0x100
printf("0x%x\n", us);
us = c + (char)uc;// uc:-128~127
// us = -128 -128 = -256即1111 1111 1000 0000 + 1111 1111 1000 0000 = 1 1111 1111 0000 0000即0xff00
printf("0x%x\n", us);
return 0;
}

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