C Program for Evaluation of Postfix ExpressionIn this program we evaluate the Postfix Expression, using the stack. For example, 456*+7- is the postfix expression, from left one by one it is inserted into the stack, and after evaluation the answer is 27. Read more about C Programming Language .

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#define SIZE 50            /* Size of Stack */
#include <ctype.h>
int s[SIZE];
int top=-1;       /* Global declarations */

push(int elem)
{                       /* Function for PUSH operation */
 s[++top]=elem;
}

int pop()
{                      /* Function for POP operation */
 return(s[top--]);
}

main()
{                         /* Main Program */
 char pofx[50],ch;
 int i=0,op1,op2;
 printf("nnRead the Postfix Expression ? ");
 scanf("%s",pofx);
 while( (ch=pofx[i++]) != '