stack.h
#include <stdlib.h>
typedef struct stack
{
int *values;
int maxSize;
int top;
}stack;
stack * createstack(int maxElements)
{
//create stack
stack *s;
s = (stack *)malloc(sizeof(stack));
//initialize
s->values = (int *)malloc(sizeof(int)*maxElements);
s->top = -1;
s->maxSize = maxElements;
//return
return s;
}
void init(stack *s,int maxElements)
{
s = (stack *)malloc(sizeof(stack));
//initialize
s->values = (int *)malloc(sizeof(int)*maxElements);
s->top = -1;
s->maxSize = maxElements;
}
void push(stack *s, int n)
{
if(s->top == s->maxSize)
{
printf("stack is Full\n");
}
else
{
printf("Pushing Value:%d\n",n);
//increament first then push
++s->top;
s->values[s->top] = n;
}
return;
}
int pop(stack *s)
{
int value;
if(s->top == -1)
{
printf("stack is Empty\n");
}
else
{
//remove first then decrement
value = s->values[s->top];
s->top--;
printf("Poping value:%d\n",value);
}
return value;
}
void display(stack *s)
{
int i=0;
for(i=0;i<=s->top;i++)
{
printf("%d ",s->values[i]);
}
}
imp.c
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "stack.h"
int calc(int n1,int n2, char c){
switch(c)
{
case '*':
return n1*n2;
break;
case '/':
return n1/n2;
break;
case '+':
return n1+n2;
break;
case '-':
return n1-n2;
break;
default:
return 0;
}
}
void main()
{
int i=0,value=0;
stack *s = createstack(10);
char *exp = "10 10 10 9 * + +";
for(i=0;i<strlen(exp);i++)
{
if(isdigit(exp[i]))
{
value = (value * 10) + (exp[i] - '0');
}
else if(exp[i] == '+' || exp[i] == '*' || exp[i] == '/' || exp[i] == '-'){
value = calc(pop(s),pop(s),exp[i]);
}
else
{
push(s,value);
value =0;
}
}
printf("%d\n",value);
}
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