Data Structure C program Queue using array Dev c++

 #include <stdio.h>  
 #define MAX 20  
 struct queue{  
       int x[MAX];  
       int front;  
       int rear;  
       }q;  
       void enqueue(int);  
       void display();  
       int dequeue();  
 int main()  
 {  
   q.front=-1;  
   q.rear=-1;  
   int ch,x,flag=1;  
   while(flag)  
   {  
    printf("1.Enqueue\n2.Dequeue\n3.Display\n4.Exit\n");   
    scanf("%d",&ch);  
    switch(ch)  
    {  
     case 1:printf("Enter element:");  
        scanf("%d",&x);  
        enqueue(x);  
        break;  
     case 2:x=dequeue();  
        printf("Removed %d\n",x);  
        break;  
     case 3:display();  
        break;  
     case 4:flag=0;  
        break;  
     defalt:printf("Wrong choice\n");  
     }  
   }  
 }  
 void enqueue(int x)  
 {  
    if(q.rear==MAX)  
    printf("Queue full\n");  
    else  
    {  
    q.x[++q.rear]=x;  
    if(q.front==-1)  
    q.front=0;  
    }  
 }  
 int dequeue()  
 {  
    if(q.rear==-1 && q.front==-1)  
    printf("Queue Empty\n");  
    else  
    return q.x[q.front++];  
 }  
 void display()  
 {  
    printf("Queue is\n");  
    int i;  
    for(i=q.front;i<=q.rear;i++)  
    printf("%d\n",q.x[i]);  
 }