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）。
1 #include<stdio.h> 2 void main(void) 3 { 4 typedef unsigned char uint8_t; 5 typedef unsigned int uint32_t; 6 int size_char = sizeof(char); 7 int size_int = sizeof(int); 8 int size_uint8 = sizeof(uint8_t); 9 int size_uint32 = sizeof(uint32_t); 10 printf("the sizeof:\nchar:%d;\nint:%d;\nuint8_t:%d;\nuint32_t:%d;\n", 11 size_char,size_int,size_uint8,size_uint32); 12 }
运行结果：
$ gcc -o an_example an_example.c $ ./an_example the sizeof: char:1; int:4; uint8_t:1; uint32_t:4;
类型转换
1 #include<stdio.h> 2 void main(void) 3 { 4 typedef int uint8_t; 5 typedef int uint32_t; 6 uint32_t a=300; 7 uint8_t b=2; 8 b=(uint8_t)a; 9 printf("a=%d, b=%d\n",a,b); 10 }
运行结果
a=300, b=300
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