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 != ' ')
{
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 = %dnn",exp,pop());
return 0;
}