当前位置: 技术问答>linux和unix
main函数中exit(0)和return(0)的区别。(linux下c编程）
来源: 互联网 发布时间：2016-12-30
本文导语: #include"stdio.h" #include"errno.h" #include"unistd.h" #include"stdlib.h" int main(void) { pid_t pid; int count=0; if((pid=vfork())==-1) { printf("vfork error:%sn",strerror(errno)); exit(1); } ...
#include"stdio.h"
#include"errno.h"
#include"unistd.h"
#include"stdlib.h"
int main(void)
{
pid_t pid;
int count=0;
if((pid=vfork())==-1)
{
printf("vfork error:%sn",strerror(errno));
exit(1);
}
count++;
printf("count=%dn",count);
return(0);
}
执行结果为：
count=1
count=1
段错误
而把return(0)换成exit(0)后
就能顺利执行呢？此时结果为
count=1
count=2
期待各位大侠回答
#include"errno.h"
#include"unistd.h"
#include"stdlib.h"
int main(void)
{
pid_t pid;
int count=0;
if((pid=vfork())==-1)
{
printf("vfork error:%sn",strerror(errno));
exit(1);
}
count++;
printf("count=%dn",count);
return(0);
}
执行结果为：
count=1
count=1
段错误
而把return(0)换成exit(0)后
就能顺利执行呢？此时结果为
count=1
count=2
期待各位大侠回答
|
Parent and child processes share the same stack space within the
[vfork,exec] window. If the size of the stack has been changed
within this window by the child process (return from or call to a
function, for example), it is likely that the parent and child
processes will be killed with signal SIGSEGV or SIGBUS.
[vfork,exec] window. If the size of the stack has been changed
within this window by the child process (return from or call to a
function, for example), it is likely that the parent and child
processes will be killed with signal SIGSEGV or SIGBUS.
|
vfork() differs from fork(2) in that the parent is suspended until the child
terminates (either normally, by calling _exit(2), or abnormally, after
delivery of a fatal signal), or it makes a call to execve(2). Until that
point, the child shares all memory with its parent, including the stack. The
child must not return from the current function or call exit(3), but may call
_exit(2).
terminates (either normally, by calling _exit(2), or abnormally, after
delivery of a fatal signal), or it makes a call to execve(2). Until that
point, the child shares all memory with its parent, including the stack. The
child must not return from the current function or call exit(3), but may call
_exit(2).
|
正如4楼所说，问题在于vfork.
如果没有使用vfork(), 在main函数中return (0)和exit(0)是没有区别的。
|
#include"stdio.h"
#include"errno.h"
#include"unistd.h"
#include"stdlib.h"
int main(void)
{
pid_t pid;
int count=0;
if((pid=vfork())==-1)
{
perror("vfork()");
exit(1);
}
count++;
printf("%dn",getpid());
printf("count=%dn",count);
exit (0);
}
return 0时，一部分结果
22985
count=1
15974
count=2
22986
count=1
15974
count=2
22987
count=1
15974
count=2
22988
count=1
15974
count=2
22989
count=1
15974
count=2
22990
count=1
15974
count=2
22991
count=1
15974
count=2
22992
count=1
15974
exit 0时的结果：
23037
count=1
23036
count=2
return 0只是告诉linux main函数的返回值是0
由于创建进程时，没结束进程的运行，父子进程会一直运行下去
exit 0表示正常退出函数
|
return(0) 在main函数中返回是等同于exit(0)的,exit(0) 无非就是做下清理工作
ls说上父进程会一直跑下去？测试过没？
ls说上父进程会一直跑下去？测试过没？
|
return 函数返回。。结束一个函数
exit是抛出异常。。。结束整个进程
exit是抛出异常。。。结束整个进程
|
您可能感兴趣的文章:
本站(WWW.)旨在分享和传播互联网科技相关的资讯和技术，将尽最大努力为读者提供更好的信息聚合和浏览方式。
本站(WWW.)站内文章除注明原创外，均为转载、整理或搜集自网络。欢迎任何形式的转载，转载请注明出处。
本站(WWW.)站内文章除注明原创外，均为转载、整理或搜集自网络。欢迎任何形式的转载，转载请注明出处。