Practical-4 || Data Structures || Postfix Evaluation Using Stacks

Practical-4 || Data Structures || Postfix Evaluation Using Stack.c

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
#define max 100
int st[max],top = -1;
//todo Function prototypes
void push(int );
int pop ();
//todo push Function
void push(int c)
{
    if (top == max-1){
        printf("\nStack is Full (type a short equation)");
    }
    else{        
        top++;       
        st[top]= c;
    }
}
//todo pop Function
int pop() {
   char val;
    if (top == -1) {
        //!printf("\nStack is empty");
    }
    else{
        val=st[top];
        top--;
    }
    return val;
}
//todo main function
void main()
{
    char exp[100];
    int i=0;
    int op1,op2,val,num;
    printf("\nEnter the postfix expression :\n ");
    scanf("%s",exp);
    do
    {
        if (exp[i]!='+'&& exp[i]!='-'&& exp[i]!='*'&&exp[i]!='/'&&exp[i]!='^'){
           num = exp[i] - '0';          
           push(num);
        }
        else 
        {           
            op2=pop();
            op1=pop();
            switch(exp[i]){
                
                case '+': val = op1 + op2;
                    break;

                case '-': val = op1 - op2;
                    break;

                case '*':  val = op1 * op2;
                    break;

                case '/': val = op1 / op2;
                    break;

                case '^':  val = pow(op1, op2);
                    break;
                }             
                        
            push(val);
        }
        i++;
    } while (i<strlen(exp));
    printf("The solution of the given expression is %d.\n",val);
}