gdb调试技巧 32位和64位
apple:socket apple$ gcc test64.c
apple:socket apple$ ./a.out
__x86_64__apple:socket apple$
apple:socket apple$ gcc -m32 test64.c
apple:socket apple$ ./a.out
__i386__apple:socket apple$
代码如下

#include <stdio.h>

int main(int argc  ,char* argv)

{

   #ifdef __x86_64__

        printf("__x86_64__");

   #elif __i386__

        printf("__i386__");

   #endif

   return 0;

}

－－－－－－－－－
写了个socket，64位系统保错，32位不报错
使用gcc -m32 -o server server.c 编译解决

/* server.c */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MAXLINE 80
#define SERV_PORT 8000

int main(void)
{
	struct sockaddr_in servaddr, cliaddr;
	socklen_t cliaddr_len;
	int listenfd, connfd;
	char buf[MAXLINE];
	char str[INET_ADDRSTRLEN];
	int i, n;

	listenfd = socket(AF_INET, SOCK_STREAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	servaddr.sin_port = htons(SERV_PORT);
    
	bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

	listen(listenfd, 20);

	printf("Accepting connections ...\n");
	while (1) {
		cliaddr_len = sizeof(cliaddr);
		connfd = accept(listenfd, 
				(struct sockaddr *)&cliaddr, &cliaddr_len);
	  
		n = read(connfd, buf, MAXLINE);
		printf("received from %s at PORT %d\n",
		       inet_ntop(AF_INET, &cliaddr.sin_addr, str,sizeof(str)),
		       ntohs(cliaddr.sin_port));
    
		for (i = 0; i < n; i++)
			buf[i] = toupper(buf[i]);
		write(connfd, buf, n);
		close(connfd);
	}
}

client:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define MAXLINE 80
#define SERV_PORT 8000

int main(int argc, char *argv[])
{
	struct sockaddr_in servaddr;
	char buf[MAXLINE];
	int sockfd, n;
	char *str;
    
	if (argc != 2) {
		fputs("usage: ./client message\n", stderr);
		exit(1);
	}
	str = argv[1];
    
	sockfd = socket(AF_INET, SOCK_STREAM, 0);

	bzero(&servaddr, sizeof(servaddr));
	servaddr.sin_family = AF_INET;
	inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
	servaddr.sin_port = htons(SERV_PORT);
    
	connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

	write(sockfd, str, strlen(str));

	n = read(sockfd, buf, MAXLINE);
	printf("Response from server:\n");
	write(STDOUT_FILENO, buf, n);

	close(sockfd);
	return 0;
}

查找问题的时候参考这个链接http://jimmyleeee.blog.163.com/blog/static/930961820103822435873/