StacK programme in 'C'

hello friends...

this is a code implementing stack(PusH, PoP & Display function)..

Software Used : Turbo C++


Code:



#include
#include
int push(int *, int, int);           //PusH fxn-adds item in stack
int pop(int *,int);                    //PoP fxn - deletes item from stack
void display(int *, int);          //Display fxn -displays stack
int menu();                             //Menu fxn-ask wat user wanna do
int again();                             //Again fxn-ask to continue..




int top,maxstack;                  //global variable  
void main()
{
int stack[6],item,i,j,choice,askmore;
maxstack=5;                       //stack size defined
    top=-1;
clrscr();
printf("hello\n");


while(choice!=3)
{ clrscr();
printf(" top =%d     elements = %d\n",top,top+1);
display(stack,top);
printf("\n\n\n ");
choice=menu();                  //menu fxn is called for asking user preference
switch(choice)                    //switch-to according to user's choice                     
{
case 1: top=push(stack,top,maxstack);     //calls PusH & value of ToP is returned
printf(" top =%d",top);
askmore=again("enter");
if(askmore==1)                               //asks for more PusH operation cont. if yes else it breaks
{ top=push(stack,top,maxstack);
printf(" top =%d",top);
}
break;
case 2: top=pop(stack,top);           //calls PoP fxn & returns ToP value
printf(" top =%d",top);
askmore=again("delete");          //ask for more PoPing..so continues if user says YES
if(askmore==1)
{ top=pop(stack,top);
printf(" top =%d",top);
}
break;
case 3: display(stack,top);          //called for Display only
break;
case 4: exit(0);           //user can exit on hitting 4
}
getch();         // to stop at scareen after each cycle of while looP
}
getch();
}


int push(int *stack,int top,int maxstack)  //body of Push fxn
{
int item;                                            //item to be added in stack is initialised
printf("\n Enter item in stack\n  ");  
scanf("%d",&item);              //Item entered by user
if(top==maxstack)                          //Overflow condition is checked
{printf("overflow");
}
else                                                 //on nonoccurence of overflow..push operation is performed
{top=top+1;                                    //by incrementing ..TOP is set to Zer0
stack[top]=item;                             //Item inserted in stack
}
printf(" %d is at %d",stack[top],top);  //position of item in stack is displayed
return(top);        //returns 'TOP' value
}
int pop(int *stack,int top)            //PoP fxn Body
{ int item;                        //Item to be deleted is defined
printf("\n Deleting item");      //just to show control
if(top==-1)                //checks occurence of UNDERFLOW condition
{printf("Underflow");
}
else       //On nonoccurence of  UNDERFLOW ..item at TOP of stack is deleted
{top=top-1;  //By decrementing ,TOP is made to point the Item present next to the 
                        ITEM to be deleted.  
item=stack[top];  //Item is placed at the top of stack
}
printf("\n Item deleted = %d",stack[top+1]);  //shows Deleted ITEM and its position in stack
                                                                            assuring that deleted IteM was the TOPmost one
printf("\n Item at the new top = %d",item);   //displays new item at the ToP
return(top);  //returns TOP
}


void display(int *stack,int top)
{       int i;
printf("\n stack is as :");


for(i=0;i<=top;i++)    //Displays items present in stack upto TOP of stack from bottom 
{
printf("%d ",stack[i]);  
}


}
int menu()                   //menu fxn  body is created
{ int  choice;
printf("\n 1.PUSH      2.POP      3.Display  4.Exit \n\n");  //Menu created...and displayrd
scanf("%d",&choice);
return(choice);
}
int again(string)        // asking for continue ..if wanna do-click 'YES'...else click 'NO'
{             int askmore;
printf("\n\n\nWant to %s more...press accordingly...",string);
printf("\n 1.yes    2. no \n\n ");
scanf("%d",&askmore);
return(askmore);                    //return..the reply from user in form of integer
                                                   -- 1. for 'YeS' & 2. for 'NO' 
                                                  
}

...StacK ...