infix -> postfix

//program to infix to post fix
#include<stdio.h>
#include<conio.h>
#include<string.h>
char infix[50],postfix[50],stack[50];
int top=-1;
void push(char ch)
{
	top++;
	stack[top]=ch;

}
char pop()
{
	char ch;
	ch=stack[top];
	top--;
	return ch;
}
int main()
{

	int i,j=0;
	clrscr();
	printf("\nENter the Infix EXPRESSION: ");
	gets(infix);
	for(i=0;i<strlen(infix);i++)
	{
		switch(infix[i])
		{
			case '[':
			push('[');
			break;

			case ']':
			while(stack[top]!='[')
			{
				postfix[j]=pop();
				j++;

			}
			top--;
			break;
			case '(':
			push('(');
			break;

			case ')':
			while(stack[top]!='(')
			{
				postfix[j]=pop();
				j++;

			}
			top--;
			break;

			case '^':
			while(stack[top]=='^')
			{
				postfix[j]=pop();
				j++;
			}
			push(infix[i]);
			break;

			case '*':
			case '/':
			while(stack[top]=='^' || stack[top]=='*' || stack[top]=='/')
			{
				postfix[j]=pop();
				j++;
			}
			push(infix[i]);
			break;

			case '+':
			case '-':
			while(stack[top]=='^' || stack[top]=='*' || stack[top]=='/'|| stack[top]=='-'|| stack[top]=='+')
			{
				postfix[j]=pop();
				j++;
			}
			push(infix[i]);
			break;

			default:
			postfix[j]=infix[i];
			j++;

		}

	}while(top!=-1)
	{
		postfix[j]=pop();
		j++;

	}
	postfix[j]=NULL;
	printf("\n %s  <--- INFIX TO POSTFIX --->  %s",infix,postfix);
	getch();
	return 0;
}