How to check for null strings in a C array

Question

I have a C array declared like char* arrayOfVarNames[3];

This array is populated by some api and the strings in this array are again used by an objective-C method.

I want to know if there are any null strings in the arrayOfVarNames[3] before passing to the objective-C method. NSString *tempString = [NSString stringWithCString:arrayOfVarNames[i] encoding:NSUTF8StringEncoding]; Anyway to check for null strings?

If you mean empty strings, then strlen(the_char_ptr)==0. If you mean null pointers, then the_char_ptr==NULL. — juanchopanza
– juanchopanza, Commented Sep 16, 2014 at 15:36

rmaddy · Accepted Answer · 2014-09-16 15:38:54Z

2

A simple if statement:

NSString *tempString = nil;
if (arrayOfVarNames[i]) {
    // It's not NULL
    tempString = [NSString stringWithCString:arrayOfVarNames[i] encoding:NSUTF8StringEncoding];
} else {
    tempString = @""; // or some other appropriate action
}

answered Sep 16, 2014 at 15:38

rmaddy

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Cy-4AH · Accepted Answer · 2014-09-16 15:48:15Z

0

One line code solution:

NSString *tempString = NULL == arrayOfVarNames[i] ? nil : [NSString stringWithCString:arrayOfVarNames[i] encoding:NSUTF8StringEncoding];

answered Sep 16, 2014 at 15:48

Cy-4AH

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Deduplicator · Accepted Answer · 2014-09-16 15:48:17Z

0

Depending on what you mean with a null string, you test for:

The pointer being NULL: !p
The pointer pointing to an empty string: !*p

Beware that some interfaces handle those cases as interchangeable, so that you must accept both as an empty string.

answered Sep 16, 2014 at 15:48

Deduplicator

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