程序样例

以下程序样例 foo.c 直接对比说明了 LP64 数据模型与 ILP32 数据模型的不同结果。同一个程序既可以编译为 32 位程序，也可以编译为 64 位程序。

#include <stdio.h>

int

main(int argc, char *argv[])

{

		(void) printf("char is \t\t%lu bytes\n", sizeof (char));

		(void) printf("short is \t%lu bytes\n", sizeof (short));

		(void) printf("int is \t\t%lu bytes\n", sizeof (int));

		(void) printf("long is \t\t%lu bytes\n", sizeof (long));

		(void) printf("long long is \t\t%lu bytes\n", sizeof (long long));

		(void) printf("pointer is \t%lu bytes\n", sizeof (void *));

		return (0);

} 

32 位编译的结果是：

% cc -O -o foo32 foo.c

% foo32 

char is          1 bytes

short is         2 bytes

int is           4 bytes

long is          4 bytes

long long is     8 bytes

pointer is       4 bytes   

64 位编译的结果是：

% cc -xarch=generic64 -O -o foo64 foo.c 

% foo64

char is          1 bytes

short is         2 bytes

int is           4 bytes

long is          8 bytes

long long is     8 bytes 

pointer is       8 bytes

缺省编译环境旨在最大化可移植性，即创建 32 位应用程序。