# Distinguish Parent and Child Process

Before we discuss in details, let's try the following code:

```c
/* LetsFork/fork2.c */
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

int main(int argc,char* argv[])
{
    int res;
    printf("Before fork():PID[%d]\n",getpid());
    res = fork();
    printf("The value of res is %d\n",res);
    if(res == 0)
    {   
        printf("I am child! PID: [%d]\n",getpid());
    }
    else
    {
        printf("I am parent! PID: [%d]\n",getpid());
    }
    printf("Program Terminated!\n");
    return 0;
}
```

The output is as follows:

![](https://848802932-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lp-5TQgFcJFf9qOBUEC%2F-Lp-5ZB50WXwtZaIRVKh%2F-Lp-64Um0BDtzoEqA01m%2Fforkc2.png?generation=1568738670943023\&alt=media)

The original process has the PID 2072. After `res = fork();`, the process splits into two, the **parent** and **child**.

For the **parent**, the return value of `fork()` is the *PID of the new **child***. However, for the **child**, the return value is ***0***.

By using this condition, we can distinguish **parent** and **child**.