Week 7 programs based on implementation of stack

Source Code

//C Program to Evaluate POSTFIX Expression Using Stack
#include<stdio.h>
int stack[20];
int top = -1;
void push(int x)
{
    Stack[++top] = x;
}
int pop()
{
    return stack[top--];
}
int main()
{
    char exp[20];
    char *e;
    int n1,n2,n3,num;
    printf(“Enter the expression :: “);
    Scanf(“%s”,exp);
    E = exp;
    while(*e != ‘\\0’)
    {
        if(isdigit(*e))
        {
            Num = *e – 48;
            Push(num);
        }
        else
        {
            N1 = pop();
            N2 = pop();
            Switch(*e)
            {
            case ‘+’:
            {
                N3 = n1 + n2;
                Break;
            }
            case ‘-‘:
            {
                N3 = n2 – n1;
                Break;
            }
            case ‘*’:
            {
                N3 = n1 * n2;
                Break;
            }
            case ‘/’:
            {
                N3 = n2 / n1;
                Break;
            }
            }
            Push(n3);
        }
        E++;
    }
    printf(“\\nThe result of expression %s  =  %d\\n\\n”,exp,pop());
    return 0;
}