Program to Covert Infix to Postfix notation

Hello friends here is a sample program to convert infix to postfix expression.

InfixToPostfix.cpp
#include<stdio.h>
#include<conio.h>
int getprec(char);
int check(char *);
void main() {
    char a[100],stack[100];
    int top=-1,i,j;
    clrscr();
    printf("\nEnter the infix expression:");
    gets(a);
    printf("\nPostfix notation is:");
    if(check(a)) {
        for(i=0;a[i]!='\0';i++) {
            if((a[i]>=97&&a[i]<=122)||(a[i]>=65&&a[i]<=90)||(a[i]>=48&&a[i]<=57))
                printf("%c",a[i]);
            else if(a[i]==')') {
                while(top>=0&&stack[top]!='(') {
                    printf("%c",stack[top]);
                    top--;
                }
                if(stack[top]=='(')
                   top--;
            }
            else {
                if((stack[top-1]=='(')&&(a[i]!='(')&&top>0) {
                    j=getprec(a[i]);
                    while(j<=getprec(stack[top])&&top>=0&&stack[top]!='(') {
                        printf("%c",stack[top]);
                        top--;
                    }
                }
                stack[++top]=a[i];
            }
        }
        while(top>=0) {
             printf("%c",stack[top]);
             top--;
        }
    }
    else
        printf("\nBrases arenot completely closed");
    getch();
}
int check(char *a) {
    int i,l=0,r=0;
    for(i=0;a[i]!='\0';i++)
        if(a[i]=='(')
            l++;
        else if(a[i]==')')
            r++;
    if(l==r)
        return 1;
    return 0;
}
int getprec(char c) {
    switch(c) {
         case '+':return 1;
         case '-':return 1;
         case '*':
         case '/':
         case '%':return 2;
         default:return 999;
    }
}

Have fun.....