Using Scanf() in child process executed via execv not working - c

Question

I am executing a really simple program which takes input in integer from user using scanf. I execute this program as a child program via fork() and execv.The child program never takes input from user.Any help would be appreciated.
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
pid_t childpid;
if((childpid = fork()) == -1)
{
perror("fork");
exit(1);
}
if(childpid == 0)
{
execv("child",NULL);
exit(1);
}
else
{
printf("Parent process is terminating...\n");
return 0;
}
}
and the child code is
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
int temp;
printf("This is Child Process. Child is going to sleep for 5 seconds\n");
sleep(5);
printf("Please enter an integer to terminate the process ");
scanf("%d",&temp);
printf("You entered %d ",temp);
printf("Child terminated");
return 0;
}
OUTPUT
[#localhost cascading]$ ./cascading
Parent process is terminating...
[#localhost cascading]$ This is Child Process. Child is going to sleep for 5 seconds
Please enter an integer to terminate the process You entered 12435[#localhost cascading]$ ^C
[#localhost cascading]$
I am running the code in fedora installed on a virtual machine.Thanks

Answer 1

Once the parent process finishes, control is returned to shell; and stdin could be closed.
To retain child's access to stdin, you can let the parent wait until the child is done.
So, in your parent:
else {
printf("Parent process is terminating...\n");
wait(NULL);
return 0;
}

Answer 2

You need to wait for child process to be finished, please modify your code like this
if(childpid == 0)
{
execv("child",NULL);
exit(1);
}
else
{
wait(); //wait for child
printf("Parent process is terminating...\n");
return 0;
}