infix -> prefix

//infix -> prefix
#include<stdio.h>
#include<conio.h>
#include<string.h>
char stack[50],infix[50],prefix[50];
int top=-1;
char pop()
{
	char ch;
	ch=stack[top];
	top--;
	return ch;
}
void push(char ch)
{
	top++;
	stack[top]=ch;
}
int  main()
{
	int i,j=0;
	clrscr();

	printf("\nEnter the Infix expression: ");
	gets(infix);
	strcat(infix,")");    //insert ENd ")"
	strrev(infix);         //revers string
	strcat(infix,"(");    //insert starting"("
	puts(strrev(infix));
	strrev(infix);
	for(i=0;i<=strlen(infix);i++)
	{
		switch(infix[i])
		{
			case ')':
			push(')');
			break;

			case '(':

			while(stack[top]!=')')
			{
				prefix[j]=pop();
				j++;

			}
			top--;
			break;

			case '^':
			push('^');
			break;

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

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

			default:
			prefix[j]=infix[i];
			j++;
		}
		printf("\n[%d]-> %c  ||  %s  ||  %s  \n",i+1,infix[i],stack,prefix);

	}
	while(top!=-1)
	{
		prefix[j]=pop();
		j++;
	}
	stack[0]=NULL;
	printf("\n[%d]-> %c  ||  %s  ||  %s  \n",i+1,infix[i],stack,strrev(prefix));
	prefix[j]=NULL;
	printf("\n %s  <=== INFIX TO PREFIX ===>  %s",strrev(infix),prefix);
	getch();
	return 0;
}