标签：符号 程序设计 截断 有符号 开始 无符号 sizeof pre 整数
扩展：
char src;
int dst;
dst = (char)src;
src有符号，扩展位=符号位，符号位0扩展位也是0，符号位1扩展位也是1
src无符号，扩展位=0
截断：
int src;
char dst;
dst =(char)src;
从低字节开始，截取sizeof(dst)个字节的十六进制数值
整型转换，只与十六进制数值有关系
int i = -1;
整数-1
0xFFFFFFFF十六进制数值
扩展：
int to unsigned int
#include <stdio.h>
#include <stdlib.h>
int main()
{
int int_num = -1;
unsigned int uint_num = (unsigned int)int_num;//强制转换，显式转换
printf("%x %d\n", int_num, int_num);
printf("%x %u\n", uint_num, uint_num);
system("pause");
return 0;
}
ffffffff -1
ffffffff 4294967295
请按任意键继续. . .
char to int
char to unsigned int
#include <stdio.h>
#include <stdlib.h>
int main()
{
char char_num = -1;
int int_num = (int)char_num;
unsigned int uint_num = (unsigned int)char_num;
printf("%hhx %hhd\n", char_num, char_num);
printf("%x %d\n", int_num, int_num);
printf("%x %u\n", uint_num, uint_num);
system("pause");
return 0;
}
ff -1
ffffffff -1
ffffffff 4294967295
请按任意键继续. . .
char to int
char to unsigned int
#include <stdio.h>
#include <stdlib.h>
int main()
{
char char_num = 1;
int int_num = (int)char_num;
unsigned int uint_num = (unsigned int)char_num;
printf("%hhx %hhd\n", char_num, char_num);
printf("%x %d\n", int_num, int_num);
printf("%x %u\n", uint_num, uint_num);
system("pause");
return 0;
}
1 1
1 1
1 1
请按任意键继续. . .
unsigned char to int
unsigned char to unsigned int
#include <stdio.h>
#include <stdlib.h>
int main()
{
unsigned char char_num = 0xFF;
int int_num = (int)char_num;
unsigned int uint_num = (unsigned int)char_num;
printf("%hhx %hhd\n", char_num, char_num);
printf("%x %d\n", int_num, int_num);
printf("%x %u\n", uint_num, uint_num);
system("pause");
return 0;
}
ff -1
ff 255
ff 255
请按任意键继续. . .
截断：
#include <stdio.h>
#include <stdlib.h>
int main()
{
int int_num = -0x12345678;
short short_num = (short)int_num;
unsigned short unshort_num = (unsigned short)int_num;
printf("int %x %d\n", int_num, int_num);
printf("short %hx %hd\n", short_num, short_num);
printf("unshort %hx %hu\n", unshort_num, unshort_num);
system("pause");
return 0;
}
int edcba988 -305419896
short a988 -22136
unshort a988 43400
请按任意键继续. . .
网易云课堂_艾叔：零基础一站式C语言|C程序设计精讲_章节5整型_课时41整型转换、扩展与截断
标签：符号 程序设计 截断 有符号 开始 无符号 sizeof pre 整数
原文地址：http://www.cnblogs.com/denggelin/p/6158273.html
