Compare two strings

This program accepts two strings from user as input and compares the two strings . Each and every character of the string is considered for comparision.If the character is in small case then the ASCII value of upper case is calculated.Then both the characters are compared.If any mismatch is found then the while loop breaks and it returns that strings are not same.If the while loop continous till it end then the strings are equal.

#include < stdio.h >
#include < conio.h > 
void main()
{
	char str1[100],str2[100];
	char ch1,ch2;
	int i,j;
	clrscr();
	printf("\nEnter first string \n");
	gets(str1);
	flushall();
	printf("\nEnter second string \n");
	gets(str2);
	i = j = 0;
	while ( str1[i] && str2[j] )
	{
		if ( str1[i] != str2[j])
		{
			if ( str1[i] >='a' && str1[i] <='z' )
				ch1= str1[i] - 32;
			else
			if ( str1[i] >='A' && str1[i] <='Z' )
				ch1 = str1[i];			
			if ( str2[j] >='a' && str2[j] <='z' )
				ch2= str2[j] - 32;
			else
			if ( str2[j] >='A' && str2[j] <='Z' )
				ch2 = str2[j];
			if ( ch1 != ch2 )
			{
				printf("\nNot equal");
				exit(0);
			}
		}
		i++;
		j++;
	}
	if ( !str1[i] && !str2[j] )
	printf("\nEqual");
} // main