[英]why there is an error when executing the fork() system call?
there is an error when trying to executing the fork() call. 尝试执行fork()调用时发生错误。 warning: implicit declaration of function 'fork' [-Wimplicit-function-declaration fork();
警告:函数“ fork”的隐式声明[-Wimplicit-function-declaration fork(); here is my code
这是我的代码
#include <stdio.h>
int main()
{
int a, b;
b = fork();
printf("hello");
if (b == 0)
{
printf("child");
}
else
{
printf("parent");
}
}
Try 尝试
#include <stdio.h>
#include <unistd.h>
int main()
{
int a;
pid_t b;
b = fork();
printf("hello");
if (b == 0)
{
printf("child");
}
else
{
printf("parent");
}
}
Generally, the error -Wimplicit-function-declaration
is only thrown when the method or function that you're trying to use has not been defined in any of the headers that have been included. 通常,仅当您尝试使用的方法或函数未在包含的任何标头中定义时,才引发
-Wimplicit-function-declaration
错误。
eg: trying to use printf
without including stdio.h
例如:尝试在不包含
stdio.h
情况下使用printf
The fork function is included from unistd.h
. fork函数包含在
unistd.h
。
## try this code##
#include <stdio.h>
#include <unistd.h>
int main()
{
int a;
pid_t b;
b = fork();
printf("HELLO");
if (b == 0)
{
printf("child");
}
else
{
printf("parent");
}
} }
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