C Program for String Comparison without using Built in Function

#include <string.h>
#include <stdio.h>

int main()
{
    int i,flag=0;
    char str[50],str1[50],ch,ch1;
    printf("\nEnter the First String : " );
    gets(str);
    printf("\nEnter the Second String : " );
    gets(str1);
    for(i=0; str[i]!='\0'; i++)
    {
        ch=str[i];
        ch1=str1[i];
        if(ch>=97 && ch<=122)
        {
            ch-=32;
        }
        if(ch1>=97 && ch1<=122)
        {
            ch1-=32;
        }
        if(ch!=ch1)
        {
            flag=1;
            break;
        }
    }

    if(flag==0)
    {
        printf("\n Both  Strings  %s and  %s are Equal ",str,str1);
    }
    else
    {
        printf("\n Both  Strings  %s and  %s are Not Equal ",str,str1);
    }
    return 0;
}