postfix evaluation using stack

#include <iostream>
 #include <iomanip>
 #include <fstream>
 #include<stdio.h>
 #include<ctype.h>
 #include<stdlib.h>
 using namespace std;
 #define SIZE 40
 int stack[SIZE];
 int top=-1;
 
void push(int n)
 {
 if(top==SIZE-1)
 {
 printf("Stack is full\n");
  system("pause");
 return;
 }
 else
 {
 top=top+1;
 stack[top]=n;
 printf("Pushed element is %d\n",n);
  system("pause");
 }
 }
 
int pop()
 {
 int n;
 if(top==-1)
 {
 printf("Stack is empty\n");
  system("pause");
 return 0;
 }
 else
 {
 n=stack[top];
 top=top-1;

 return(n);
 }
 }
 



int main() 
{
 
int str[50],ch;

 int i=0;
 int n,op1,op2;

 ifstream inFile;
 ch=str[i];

 inFile.open("D:\\me.txt");
 if (!inFile) 
{
 printf( "Unable to open file");
 system("pause");
 exit(1); // terminate with error
 }

 while (inFile >> ch) 
{
 if(ch==43 || ch==45 || ch==47 || ch==42 || ch==94 || ch==37 )
 {

	 op1=pop();
	 op2=pop();
	 if (op1<op2)
	 {
	 n=op1;
	 op1=op2;
	 op2=n;
	 }
	 switch(ch)
	 {
	 case 43:
	 n=op1+op2; break;
	 case 45:
	 n=op1-op2;break;
	 case 42:
	 n=op1*op2;break;
	 case 47:
	 n=op1/op2;break;
	 case 37:
	 n=op1%op2;break;
	 case 94:
	 n=op1^op2;break;
	
 
	 default:
	 {
	 printf("The operator is not identified\n");
	 system("pause");
	 exit(0);break;
	 }
	 }
	 printf("n=%d\n",n);
	 push(n);
	 system("pause");


 }
	 else
	 {
	 n=ch;
	 push(n);
	 }
 ch=str[++i];
 }
inFile.close();
 printf("The value of the arithmetic expression is=%d\n",pop());
 system("pause");
 return 0;
 }