Question

This has given me quite a big headache. For whatever reason, when I use this code, the if statement always evaluates to false:

while(!feof(file))
{
    NSString *line = [self readNSString:file];
    NSLog(@"%@", line);
    NSLog(@"%@", search);
    NSRange textRange;
    textRange =[line rangeOfString:search];

    if(textRange.location != NSNotFound)
    {
        NSString *result = [line substringFromIndex:NSMaxRange([line rangeOfString:search])];
        resultView.text = result;
    }
    else
    {
        resultView.text = @"Not found";
    }
}

When the functions execute, the two NSLogs tell me that the “line” and “search” strings are what they should be, so then why does the if statement always evaluate to false? I must be missing something simple, having another set of eyes would be great. Thanks

edit: (function “readNSString”)

- (NSString*)readNSString:(FILE*) file
{
    char buffer[300];

    NSMutableString *result = [NSMutableString stringWithCapacity:256];
    int read;
    do
    {
        if(fscanf(file, "%299[^\n]%n%*c", buffer, &read) == 1)
            [result appendFormat:@"%s", buffer];
        else
            break;
    } while(r == 299);

    return result;
}

edit 2:

search is set with a call to the first function, with an NSString* variable as a parameter, like this:

NSString *textFieldText = [[NSString alloc]
                              initWithFormat:@"%@", textField.text];

[self readFile:textFieldText];

edit 3 (NSLogs output)

line: Germany Italy France

search: Italy

Answer 1

I think that you are using the rangeOfString and the NSNotFound etc. correctly, so the problem is possibly to do with the creation of the string from the data read from the file using the appendFormat:@"%s".

I suspect there may be an encoding issue between your two string formats – I would investigate whether the “%s” encodes the null terminated C string properly into the same format as a unicode NSString with the appropriate encoding.

Try hard coding the value you are getting from the readNSString function as a string literal in code just for testing and see if that comparison works, if so this would tend to indicate it probably is something to do with the encoding of the string created from the file.