Thread: String Comparison Issues

If I have the following test code:

Code:

String content = "This is a test";
String str = "This";
String lookFor = content.Substring(0, 5); // "This"
Boolean found = false;

// "found" should equal true, BUT IT'S NOT!!!  Why??
if (str == lookFor)
	found = true;

// "found" should equal true, BUT IT'S NOT!!!  Why??
if (str.Equals(lookFor))
	found = true;
	
// "found" should equal true, BUT IT'S NOT!!!  Why??
switch (lookFor)
{
	case "This":
		found = true;
		break;
}

In all three examples, "found" should be true, however, it never happens.

Where am I going wrong?

Thanks.

Originally Posted by Salem

> String lookFor = content.Substring(0, 5); // "This"
You ask for 5 chars, and so you have a trailing space (I guess)

That is your problem. You are comparing "This" with "This ". Never going to be equal.

Originally Posted by Salem

> String search = haystack.Substring(0, 9);
How about
String search = haystack.Substring(1,8);

> if (search.Equals(needle))
Because you're trying to compare 9 chars with 8 (again!)

Thank you. (1,8) works perfect.

Only reason I did (0,9) is because if I did (0,8), I would get "XGCa:00"

Thank you, Salem, for pointing out (1,8). This has resolved my issue.

Since you don't appear to need the needle's starting index or anything else other than a bool to confirm the needle's existance in the haystack, you could use .Contains instead...

Code:

String needle = "XGCa:004";
String haystack = "\x1DXGCa:004\r\n845123\r\n";
bool found = haystack.Contains(needle);

If you wish to insist on using Substring, you could avoid mistakes by offering the needle's character length as the substring's second parameter...

Code:

String needle = "XGCa:004";
String haystack = "\x1DXGCa:004\r\n845123\r\n";
bool found = haystack.Substring(1, needle.Length) == needle;