Page 80 - DCAP605_ADVANCED_DATA_STRUCTURE_AND_ALGORITHMS

Unit 3: Stacks

if(Isempty()) print(“statement is parenthetically balanced”); Notes
else print(“statement is parenthetically unbalanced”);
}

Lab Exercise
1. The program given below implements the stack data structure using an array. In this
program the elements are pushed into array stack[ ] through push( ) function. The
parameters passed to push( ) are the base address of the array, the position in the
stack at which the element is to be placed and the element itself. Care is taken by the
push( ) function that the user does not try to place the element beyond the bounds of
the stack. This is done by checking the value stored in pos. pop( ) function pops out
the last element stored in the stack[ ], because, pos holds the position which has the
last element in the stack.

/* To pop and push items in a stack */
#define MAX 10
void push ( int ) ;
int pop( ) ;
int stack[MAX] ;
int pos ;
void main( )
{
int n ;
clrscr( ) ;
pos = -1 ; /* stack is empty */
push ( 10 ) ;
push ( 20 ) ;
push ( 30 ) ;
push ( 40 ) ;
n = pop( ) ;
printf ( “\nitem popped out is : %d”, n ) ;
n = pop( ) ;
printf ( “\nitem popped out is : %d”, n ) ;
}
/* pushes item on the stack */
void push ( int data )
{
if ( pos == MAX - 1 )
printf ( “\nStack is full” ) ;
else
{
pos++ ;
stack[ pos ] = data ;
}

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