CODEWITHSUNDEEP
javastringreverse
ISJ
ISJ

Reputation: 509

Comparison of two strings

I have the following code:

    int t = s.length()-1;
    int g = 0;

    for (int i=0; i < s.length(); i++){

        if (s.charAt(i) != h.charAt(t--));
            g++;

    }

    if (g==0)
        return true;

    else 
        return false;

Basically what this code is suppose to do is to test if string h's inverse is equal to string s, or vice versa. For some reason a "false" is always returned - although the obvious answer is true.

Can anyone please tell me what's wrong with my code?

Thanks!

Upvotes: 3

Views: 1111

Answers (4)

Gaurav
Gaurav

Reputation: 28755

extra ; in if (s.charAt(i) != h.charAt(t--)); may create the issue

Use

if (s.charAt(i) != h.charAt(t--))
{
  g++;
  break; // if not match, not need to continue with loop
}

Upvotes: 3

Matthew Gilliard
Matthew Gilliard

Reputation: 9498

Unless this is a learning exercise, I'd recommend you avoid writing the loops yourself and use some library code. You can do:

String s = "abcd";
String h = "dcba";

System.out.println( h.equals( new StringBuffer(s).reverse().toString() ) );

or StringUtils#reverse.

Under the hood, these loop through the string in much the same way that you were doing. The code is in AbstractStringBuilder, if you'd like to take a look.

Upvotes: 1

Javed Akram
Javed Akram

Reputation: 15344

use break; to come out of the loop if it don't have same char

bool g = true;
for(.....)
{
   if (s.charAt(i) != h.charAt(t--))
   {
      g = false;
      break;
   }
}
return g;

It increases your performance

Upvotes: 0

darioo
darioo

Reputation: 47183

I'd say an extra ; is the culprit.

Instead of 

if (s.charAt(i) != h.charAt(t--));

use

if (s.charAt(i) != h.charAt(t--))

You should always go the "safe" route. That is, use braces after if-else statements (and pretty much everywhere you can use them), so bugs like this won't happen in the first place. The correct way to write it is:

if (s.charAt(i) != h.charAt(t--)) {
   g++;
}

And by the way, your code will blow up if you don't check first that s and h have the same length.

Upvotes: 8

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