how to sleep in c

1//sleep function provided by <unistd.h>
2#include <stdio.h>
3#include <stdlib.h>
4#include <unistd.h>
5 
6int main(){
7  
8	printf("Sleeping for 5 seconds \n");
9	sleep(5);
10	printf("Wake up \n");  
11}

1#include <stdio.h>
2#include <stdlib.h>
3#include <unistd.h>
4 
5int main(){
6  
7	printf("Sleeping for 5 seconds \n");
8	sleep(5);
9	printf("Sleep is now over \n");  
10}

1#include <unistd.h>
2
3unsigned sleep(unsigned seconds);

1sleep(5); //sleep for 5 secs