C语言中Linux上信号有关问题

C语言中Linux下信号问题
#include <sys/types.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>

static void sig_cld();

int main()
{
pid_t pid;

if(signal(SIGCLD, sig_cld)==-1)
{
perror("signal error");
}

if((pid=fork())<0)
{
perror("fork error");
}
else if(pid==0)
{
slee(2);
_exit(0);
}

pause();
exit();
}

static void sig_cld(void)
{
pid_t pid;
int status;

printf("SIGCLD received\n");
if(signal(SIGCLD, sig_cld)==-1)
{
perror("signal error");
}

if((pid=wait(&status))<0)
{
perror("wait error");
}
printf("pid=%d\n", pid);

return;
}

出错信息如下：

t3.c: In function ‘main’:
t3.c:12: warning: comparison between pointer and integer
t3.c:24: warning: incompatible implicit declaration of built-in function ‘_exit’
t3.c:28: error: too few arguments to function ‘exit’
t3.c: In function ‘sig_cld’:
t3.c:37: warning: passing argument 2 of ‘signal’ from incompatible pointer type
/usr/include/signal.h:101: note: expected ‘__sighandler_t’ but argument is of type ‘void (*)(void)’
t3.c:37: warning: comparison between pointer and integer

对这个不理解，希望解释一下，谢谢！

------解决方案--------------------
t3.c:28: error: too few arguments to function ‘exit’

改成
exit(0);
------解决方案--------------------
提示都非常明显了！！t3.c第28行出错了。

exit(); --> exit(0);
------解决方案--------------------
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