A simple thread example (session control) in C

cthread.c

#include <stdio.h>
#include <unistd.h>
#include <time.h>
#include <pthread.h> // necessary
#include <stdlib.h>
 
// Session limit in seconds
#define SESSION_TIME 60
 
// Global last interaction variable
time_t lastInteraction;
 
// Thread function that will control session time
void * session(void * arg)
{
	// Session will constantly check if the session is expired or not
	while(1)
	{
		// In each loop, get current time
		time_t c;
		time(&c);
		// Then compare it with the lastInteraction time
		if(c - lastInteraction >= SESSION_TIME)
		{
			printf("Session expired\n");
			exit(0);
		}
	}
}
 
int main(int argc, char const *argv[])
{
	// Set the initial interaction time
	time(&lastInteraction);
 
	// Create session
	/*
	* Note: if pthread_create executes successfuly, tid gets the return id of session. 
	* First NULL indicates we will use default attributes for our thread
	* session is the name of the method which will handle thread's execution
	* last NULL is the argument will be used inside session but I preferred using it globally
	*/
	pthread_t tid;
	pthread_create(&tid, NULL, session, NULL);
 
	// Create input string
	char input[30];
 
	// Program starts
	while(1)
	{
		// Ask user for inputs with scanf (or fgets depending on your program)
		// Assume that user waits and does not enter any thing for 60 seconds,
		// during this time thread gets executed and checks whether the limit is reached or not
		printf("Enter something: ");
		input[0] = '\0'; // optional: empty the string
		scanf("%s", input);
 
		// Update the last activation time after user gives an input
		time(&lastInteraction);
	}
 
	return 0;
}