定义类型uint8_t,uint32_t

定义的类型uint8_t,uint32_t能更明显的显示所占字节数。uint8_t表示占1个字节（1 字节=8 bit）, uint32_t表示占4个字节（（4 字节=32 bit）。

 #include<stdio.h>
  void main(void)
 {
    typedef unsigned char uint8_t;
    typedef unsigned int uint32_t;
    int size_char   = sizeof(char);
    int size_int    = sizeof(int);
    int size_uint8  = sizeof(uint8_t);
    int size_uint32 = sizeof(uint32_t);
    printf("the sizeof:\nchar:%d;\nint:%d;\nuint8_t:%d;\nuint32_t:%d;\n",
           size_char,size_int,size_uint8,size_uint32);
 }

运行结果：

$ gcc -o an_example an_example.c
$ ./an_example
the sizeof:
char:;
int:;
uint8_t:;
uint32_t:;

类型转换

 #include<stdio.h>
  void main(void)
 {
    typedef  int uint8_t;
    typedef  int uint32_t;
    uint32_t a=;
    uint8_t b=;
    b=(uint8_t)a;
    printf("a=%d,  b=%d\n",a,b);
 }

运行结果

a=,  b=

参考：

[1] 类型转换 http://www.cnblogs.com/gaoshanxiaolu/p/3601038.html

[2] 类型转换 http://blog.csdn.net/shenwansangz/article/details/50186495