double to NSData?

[SteveMobs]

How can I convert a double value to a NSData object?

Thanks!

[ChrisL]

To store a primitive type in an NSData object, you just need a pointer to the first byte of the value and the number of bytes:

double aDouble = 10.0;
NSData doubleData = [NSData dataWithBytes:&aDouble length:sizeof(double)];

You can get it back out like this:

double anotherDouble;
[doubleData getBytes:&anotherDouble length:sizeof(double)];

[SteveMobs]

Thank you! By the way... meanwhile I also found out, how to convert a double to an unsigned char array:

double aDouble = 10.0;
unsigned char doubleChars[sizeof(double)];
memcpy(doubleChars, &aDouble, sizeof(double));

[SteveMobs]

Another quiz: Is it possible to convert just the second half of a double to NSData?

I tried this, which does not work:

double aDouble = 10.0;
NSData doubleData = [NSData dataWithBytes:(&aDouble)+sizeof(double)/2 length:sizeof(double)/2];