How to convert the Char * to hexadecimal value - iphone

I have a char array that i need to convert to hexadecimal value
char* arrrr =[self mountLVparams:NULL :c :code_ward_arr];
int size =strlen(arrrr);
I am trying with this but this not happening
NSData* data = [NSData dataWithBytes:arrrr length:sizeof(sizeof(unsigned char)*size)];

Try this:
NSString *inp = [NSString stringWithString:#"MmMmMm"];
char star = [inp characterAtIndex:3];
NSString *string = [NSString stringWithFormat:#"char:%c andHex:%x",[inp characterAtIndex:3],star];
NSLog(#"%#",string);
Look at in output is "%#" as a regular string. In string you will receive hex value of char.
char:m andHex:6d
With array you will have to do it in a loop

You don't "convert" a value to hexadecimal. Hexadecimal is just a different way of counting or displaying the same numbers.
if (0xFF==255)
{
NSLog(#"255 equals 0xFF");
}
Now see the following code below which will convert your byte array into and int, then display then format the int as a hex string.
-(void) convertData: (unsigned char*) data
{
int numBytes = sizeof(int);
//convert array of bytes to NSData*
NSData* binaryData = [[NSData alloc] initWithBytes: (void*) data length: numBytes];
//read value of number stored in data, presuming it is an integer
int number = *((int*) data);
//format number as a hex string
NSString* hexString = [NSString stringWithFormat:#"%X",number];
}

Related

Convert a hash to NSString?

Using the Evernote API, I have an object which has an NSUInteger property called hash. For the specific object I'm looking at, this is equal to:
<f5b5444b 33e740b7 f9d49a3b ddb6a39c>
I want to convert this into an NSString. Doing this:
[NSString stringWithFormat:#"%d", noteResource.hash]
Gives me this:
530049088
How could I correctly convert the hash value to an NSString?
When you see something output as "<" 8 hex digits space .... ">", it's the result of logging a NSData object (NSLog(#"%#", myDataObject);). So I believe what you have is not an NSUInteger, but a NSData * object.
There is no built in method to convert between strings and data, you need to do it in code:
- (NSString *)dataToString:(NSData *)data
{
NSUInteger len = [data length];
NSMutableString *str = [NSMutableString stringWithCapacity:len*2];
const uint8_t *bptr = [data bytes];
while(len--) [str appendFormat:#"%02.2x", *bptr++];
return str;
}
If this works, you can write your own stringToData method reversing the above, if needed.

Converting NSString, data type expression, to actual NSData

NSString *string1 = #"<616263>";
I want to make this into NSData *data1 = <616263>;
so that when I
NSString *string2 = [[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding];
NSLog(#"%#", string2);
Result: abc
would come out
p.s.
<616263>, this is data expression of #"abc"
The trick is converting 616263 to abc. Since you are starting with the ASCII representation of the character codes, you need to convert your NSString to an array of bytes (or your original data source to an array instead of saving it as an NSString in the first place).
NSString *string1 = #"616263";
// Make sure that buffer is big enough!
char sourceChars[7];
[string1 getCString:sourceChars maxLength:7 encoding:NSUTF8StringEncoding];
char destBuffer[3];
char charBuffer[3];
// Loop through sourceChars and convert the ASCII character groups to char's
// NOTE: I assume that these are always two character groupings per your example!
for (int index = 0; index < [string1 length]; index = index + 2) {
// Copy the next two digits into charBuffer
strncpy(charBuffer, &sourceChars[index], 2);
charBuffer[2] = '\0';
// convert charBuffer (ie 61) from hex to decimal
destBuffer[index / 2] = strtol(charBuffer, NULL, 16);
}
// destBuffer is properly formatted: init data1 with it.
NSData *data1 = [NSData dataWithBytes:destBuffer length:[string1 length]/2];
// Test
NSString *string2 = [[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding];
NSLog(#"%#", string2); // Prints abc

How to convert properly from NSData to NSString?

I'm getting weird NSString value after performing a conversion. For example, I have one byte with value 2 (00000010) that is stored in response. I tried both NSString initWithData and initWithBytes but both return weird symbol (upside down question mark). Here's my code:
NSString *command1 = [[NSString alloc] initWithData:response encoding:NSASCIIStringEncoding];
NSString *command2 = [[NSString alloc] initWithBytes:[response bytes] length:[response length] encoding:NSASCIIStringEncoding];
NSLog(#"command1: %#", command1);
NSLog(#"command2: %#", command2);
Also tried NSUTF8StringEncoding but NSASCIIStringEncoding is correct one because data comes encoded one byte per symbol.
From what I am reading, this is what you want:
NSString *stringWithContentsOfBinaryData(NSData *data)
{
NSMutableString *output;
int len = [data length];
uint8_t *bytes = [data bytes];
for (int i = 0; i < len; i++)
{
[output appendFormat:#"%i", bytes[i]];
}
return output;
}
It just simply converts each byte to it's integer representation and concatenates that into a string.
ASCII is not necessarily the right encoding. ASCII only defines characters between 0x00 and 0x7F. If response is an HTTP response, and the encoding is not specified in the HTTP Content-Type header, the default is ISO-8859-1 for which you should use NSISOLatin1StringEncoding
And it doesn't matter what encoding you use: control characters (0x00 - 0x1F) aren't necessarily printable.

How to convert ASCII value to a character in Objective-C?

I was wondering if anyone has the following php function equivalents in Objective-C for iPhone development:
ord() # returns the ASCII value of the first character of a string.
chr() # returns a character from the specified ASCII value.
Many thanks!
This is how you can work with ASCII values and NSString. Note that since NSString is working with unichars, there could be unexpected results for a non ASCII string.
// NSString to ASCII
NSString *string = #"A";
int asciiCode = [string characterAtIndex:0]; // 65
// ASCII to NSString
int asciiCode = 65;
NSString *string = [NSString stringWithFormat:#"%c", asciiCode]; // A
//char to int ASCII-code
char c = 'a';
int ascii_code = (int)c;
//int to char
int i = 65; // A
c = (char)i;

Convert hex data string to NSData in Objective C (cocoa)

fairly new iPhone developer here. Building an app to send RS232 commands to a device expecting them over a TCP/IP socket connection. I've got the comms part down, and can send ASCII commands fine. It's the hex code commands I'm having trouble with.
So lets say I have the following hex data to send (in this format):
\x1C\x02d\x00\x00\x00\xFF\x7F
How do I convert this into an NSData object, which my send method expects?
Obviously this does not work for this hex data (but does for standard ascii commands):
NSString *commandascii;
NSData *commandToSend;
commandascii = #"\x1C\x02d\x00\x00\x00\xFF\x7F";
commandToSend = [commandascii dataUsingEncoding:NSStringEncoding];
For a start, some of the \x hex codes are escape characters, and I get an "input conversion stopped..." warning when compiling in XCode. And NSStringEncoding obviously isn't right for this hex string either.
So the first problem is how to store this hex string I guess, then how to convert to NSData.
Any ideas?
Code for hex in NSStrings like "00 05 22 1C EA 01 00 FF". 'command' is the hex NSString.
command = [command stringByReplacingOccurrencesOfString:#" " withString:#""];
NSMutableData *commandToSend= [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
for (int i = 0; i < ([command length] / 2); i++) {
byte_chars[0] = [command characterAtIndex:i*2];
byte_chars[1] = [command characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[commandToSend appendBytes:&whole_byte length:1];
}
NSLog(#"%#", commandToSend);
Here's an example decoder implemented on a category on NSString.
#import <stdio.h>
#import <stdlib.h>
#import <string.h>
unsigned char strToChar (char a, char b)
{
char encoder[3] = {'\0','\0','\0'};
encoder[0] = a;
encoder[1] = b;
return (char) strtol(encoder,NULL,16);
}
#interface NSString (NSStringExtensions)
- (NSData *) decodeFromHexidecimal;
#end
#implementation NSString (NSStringExtensions)
- (NSData *) decodeFromHexidecimal;
{
const char * bytes = [self cStringUsingEncoding: NSUTF8StringEncoding];
NSUInteger length = strlen(bytes);
unsigned char * r = (unsigned char *) malloc(length / 2 + 1);
unsigned char * index = r;
while ((*bytes) && (*(bytes +1))) {
*index = strToChar(*bytes, *(bytes +1));
index++;
bytes+=2;
}
*index = '\0';
NSData * result = [NSData dataWithBytes: r length: length / 2];
free(r);
return result;
}
#end
If you can hard code the hex data:
const char bytes[] = "\x00\x12\x45\xAB";
size_t length = (sizeof bytes) - 1; //string literals have implicit trailing '\0'
NSData *data = [NSData dataWithBytes:bytes length:length];
If your code must interpret the hex string (assuming the hex string is in a variable called inputData and lengthOfInputData is the length of inputData):
#define HexCharToNybble(x) ((char)((x > '9') ? tolower(x) - 'a' + 10 : x - '0') & 0xF)
int i;
NSMutableData *data = [NSMutableData data];
for (i = 0; i < lengthOfInputData;)
{
char byteToAppend;
if (i < (lengthOfInputData - 3) &&
inputData[i+0] == '\\' &&
inputData[i+1] == 'x' &&
isxdigit(inputData[i+2]) &&
isxdigit(inputData[i+3]))
{
byteToAppend = HexCharToNybble(inputData[i+2]) << 4 + HexCharToNybble(input[i+3]);
i += 4;
}
else
{
byteToAppend = inputData[i];
i += 1;
}
[data appendBytes:&byteToAppend length:1];
}
This is an old topic, but I'd like to add some remarks.
• Scanning a string with [NSString characterAtIndex] is not very efficient.
Get the C string in UTF8, then scan it using a *char++ is much faster.
• It's better to allocate NSMutableData with capacity, to avoid time consuming block resizing. I think NSData is even better ( see next point )
• Instead of create NSData using malloc, then [NSData dataWithBytes] and finally free, use malloc, and [NSData dataWithBytesNoCopy:length:freeWhenDone:]
It also avoids memory operation ( reallocate, copy, free ). The freeWhenDone boolean tells the NSData to take ownership of the memory block, and free it when it will be released.
• Here is the function I have to convert hex strings to bytes blocks. There is not much error checking on input string, but the allocation is tested.
The formatting of the input string ( like remove 0x, spaces and punctuation marks ) is better out of the conversion function.
Why would we lose some time doing extra processing if we are sure the input is OK.
+(NSData*)bytesStringToData:(NSString*)bytesString
{
if (!bytesString || !bytesString.length) return NULL;
// Get the c string
const char *scanner=[bytesString cStringUsingEncoding:NSUTF8StringEncoding];
char twoChars[3]={0,0,0};
long bytesBlockSize = formattedBytesString.length/2;
long counter = bytesBlockSize;
Byte *bytesBlock = malloc(bytesBlockSize);
if (!bytesBlock) return NULL;
Byte *writer = bytesBlock;
while (counter--) {
twoChars[0]=*scanner++;
twoChars[1]=*scanner++;
*writer++ = strtol(twoChars, NULL, 16);
}
return[NSData dataWithBytesNoCopy:bytesBlock length:bytesBlockSize freeWhenDone:YES];
}
If I want to hard-code the bytes, I do something like this:
enum { numCommandBytes = 8 };
static const unsigned char commandBytes[numCommandBytes] = { 0x1c, 0x02, 'd', 0x0, 0x0, 0x0, 0xff, 0x7f };
If you're obtaining these backslash-escaped bytes at run time, try the strunvis function.
Obviously this does not work for this hex data (but does for standard ascii commands):
NSString *commandascii;
NSData *commandToSend;
commandascii = #"\x1C\x02d\x00\x00\x00\xFF\x7F";
commandToSend = [commandascii dataUsingEncoding:NSStringEncoding];
For a start, some of the \x hex codes are escape characters, and I get an "input conversion stopped..." warning when compiling in XCode. And NSStringEncoding obviously isn't right for this hex string either.
First, it's Xcode, with a lowercase c.
Second, NSStringEncoding is a type, not an encoding identifier. That code shouldn't compile at all.
More to the point, backslash-escaping is not an encoding; in fact, it's largely independent of encoding. The backslash and 'x' are characters, not bytes, which means that they must be encoded to (and decoded from) bytes, which is the job of an encoding.
Another way to do it.
-(NSData *) dataFromHexString:(NSString *) hexstr
{
NSMutableData *data = [[NSMutableData alloc] init];
NSString *inputStr = [hexstr uppercaseString];
NSString *hexChars = #"0123456789ABCDEF";
Byte b1,b2;
b1 = 255;
b2 = 255;
for (int i=0; i<hexstr.length; i++) {
NSString *subStr = [inputStr substringWithRange:NSMakeRange(i, 1)];
NSRange loc = [hexChars rangeOfString:subStr];
if (loc.location == NSNotFound) continue;
if (255 == b1) {
b1 = (Byte)loc.location;
}else {
b2 = (Byte)loc.location;
//Appending the Byte to NSData
Byte *bytes = malloc(sizeof(Byte) *1);
bytes[0] = ((b1<<4) & 0xf0) | (b2 & 0x0f);
[data appendBytes:bytes length:1];
b1 = b2 = 255;
}
}
return data;
}
-(NSData*) convertToByteArray:(NSString*) command {
if (command == nil || command.length == 0) return nil;
NSString *command1 = command;
if(command1.length%2 != 0) {
// to handle odd bytes like 1000 decimal = 3E8 with is of length = 3
command1 = [NSString stringWithFormat:#"0%#",command1];
}
NSUInteger length = command1.length/2 ;
NSMutableData *commandToSend = [[NSMutableData alloc] initWithLength:length];
char byte_chars[3] = {'\0','\0','\0'};
unsigned char whole_byte;
for (int i=0; i<length; i++) {
byte_chars[0] = [command1 characterAtIndex:i*2];
byte_chars[1] = [command1 characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[commandToSend appendBytes:&whole_byte length:1];
}
NSRange commandRange = NSMakeRange(commandToSend.length - length, length);
NSData *result = [commandToSend subdataWithRange:commandRange];
return result;
}
I know this is a very old thread, but there is an encoding scheme in Objective C that can easily convert your string of hex codes into ASCII characters.
1) remove the \x from the string and with out keeping spaces in the string just convert the string to NSData using :
[[NSData alloc] initWithData:[stringToBeConverted dataUsingEncoding:NSASCIIStringEncoding]];
Hex data is just bytes in memory, you think of it as a string because that's how you see it but they could represent anything.
Try: (typed in the browser, may contain errors)
NSMutableData *hexData = [[NSMutableData alloc] init];
[hexData appendBytes: 0x1C];
[hexData appendBytes: 0x02D];
etc...