ecfeLF - Online C99 Compiler & Debugging Tool

#include<stdio.h>

#define SIZE 5
int queue[SIZE];
int head, tail;

void enqueue(int value);
int dequeue(void);

int main(void)
{
    head = tail = 0;
    int i;

    enqueue(1);
    enqueue(2);
    dequeue();
    enqueue(3);
    dequeue();
    enqueue(4);
    enqueue(5);
    dequeue();
    enqueue(6);

    for(i=0; i<SIZE; i++){
      printf("queue[%d]=%d\n", i, queue[i] );
    }
    return 0;
}

void enqueue(int value)
{
  if(head==tail+1){
  	return;
  }
    queue[tail] = value;
    tail = (tail + 1) % SIZE;
}


int dequeue(void)
{
if(head==tail){
	return-1;
}else{
	int value=queue[head];
	queue[head]=0;
	head = (head + 1) % SIZE;
	return value;
}
}