Linear Queue using Structure

#include<stdio.h>
#include<stdlib.h>
#define max 50

typedef struct Queue
{
int val[max];
int front,rear;
}qu;

void enqueu(qu *,int);
int dequeu(qu *);
int peek(qu);

int isempty(qu);
int isfull(qu);

void disp(qu);

int main()
{
int ch,v;
qu q;
q.front=q.rear=-1;
while(1)
{
printf("\n1) Insert \n2) Delete \n3)Front value\n4)Display\n5) Exit");
printf("\n Enter the choice : ");
scanf("%d",&ch);

switch(ch)
{
case 1: if(!isfull(q))
{
printf("\n Enter the value : ");
scanf("%d",&v);
enqueu(&q,v);
}
else
printf("\nNo more space");
break;
case 2: if(!isempty(q))
{
v=dequeu(&q);
printf("\nThe deleted value from the front is %d",v);
}
else
printf("\nNothing to delete");
break;
case 3: if(!isempty(q))
{
printf("\nThe Value at the front is %d",peek(q));
}
else
printf("\nNothing in the queue");
break;
case 4: if(!isempty(q))
{
printf("\nValues are");
disp(q);
}
else
printf("\nNothing in the queue");
break;
case 5: exit(1);
default: printf("\nNot in the menu");
}
}
}


void enqueu(qu *q,int f)
{
int i;
if(q->front==-1)
q->front=q->rear=0;
else if(q->rear==max-1)
{
for(i=q->front;i<=q->rear;i++)
q->val[i-(q->front)]=q->val[i];
q->rear=i-(q->front);
q->front=0;
}
else
q->rear++;
q->val[q->rear]=f;
}


int dequeu(qu *q)
{
int g;
g=q->val[q->front];
if(q->front==q->rear)
q->front=q->rear=-1;
else
q->front++;
return g;
}


int peek(qu p)
{
return p.val[p.front];
}


int isempty(qu p)
{
if(p.front==-1)
return 1;
else
return 0;
}

int isfull(qu q)
{
if(q.front==0 && q.rear==max-1)
return 1;
else
return 0;
}

void disp(qu q)
{
int g;
g=q.front;
for(;g<=q.rear;g++)
printf("\n%d",q.val[g]);
}


I/O;