Converting Hex String to ASCII String showing wrong result for 00

Question

below is my method for Hex to ASCII conversion

-(NSString*)getASCIIString:(NSString*)strHex
{
    NSMutableString *strAscii = [NSMutableString string];
    for (int i=0;i<24;i+=2) {
        NSString *charValue = [strHex substringWithRange:NSMakeRange(i,2)];
        unsigned int _byte;
        [[NSScanner scannerWithString:charValue] scanHexInt: &_byte];
        if (_byte >= 32 && _byte < 127) {
            [strAscii appendFormat:@"%c", _byte];
        } else {
            [strAscii appendFormat:@"[%d]", _byte];
        }
    }
    NSLog(@"Hex: %@", strHex);
    NSLog(@"Ascii: %@", strAscii);
    return strAscii;
}

Above methode convert Hex String to ASCII but i notice for one scenario giving me wrong result as below:

strHex : 4E4932313533000000000066 Ascii : NI2153[0][0][0][0][0]f (Wrong)

why for 00 i am getting [0]. ?

my method work perfectly fine , only when there is 00 in Hex string as i mentioned i am getting [0] in Ascii string.

Please Let me know tested perfect conversion method.

maybe [this](https://stackoverflow.com/questions/6421282/how-to-convert-hex-to-nsstring-in-objective-c) is what you looking for? — Tj3n, Aug 03 '17 at 07:31
no my method work perfectly fine , only when there is 00 in Hex string as i mentioned i am getting [0] in Ascii string. it should not be .... — user2813740, Aug 03 '17 at 07:33
According to your code the output is correct since a zero byte (hex `0x0)` is a non-printable character and not in the range 32 .. 127. Don't mix it up with the *letter* 0 which is hex `0x30` — vadian, Aug 03 '17 at 07:56

score 1 · Accepted Answer · answered Aug 03 '17 at 07:43

1

If the hex string is 00, you get the value 0 in _byte, and thus you are in the else branch, and get [0] as result for [strAscii appendFormat:@"[%d]", _byte];.

answered Aug 03 '17 at 07:43

clemens

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yes i know but is that correct way....i wanted solution...if any one has handle this condition.... – user2813740 Aug 03 '17 at 07:45
What is your required result? – clemens Aug 03 '17 at 07:45
i really don't know ...i need standard way...just now i checked on google ...00 meaning NUL... is that correct way to handle .. i am missing some thing... – user2813740 Aug 03 '17 at 07:49
Perhaps, you could add a branch `else if(_byte == 0) { [strASCII appendString:@"NUL"]; }` in front of the else branch. – clemens Aug 03 '17 at 07:55

Converting Hex String to ASCII String showing wrong result for 00

1 Answers1