How to find out the format of a float?

Question

I'm working with someone else's code, and there is a float with some unusual qualities.

If I output the float using:

NSLog(@"theFloat: %f", record.theFloat);

I get:

theFloat: 0.000000

However, if I use:

NSLog(@"(int)theFloat = %i", (int) record.theFloat);

I get:

(int)theFloat: 71411232

How do I discover the real format and value of theFloat? I know that it should contain a large number.

Incidentally, the Record class which contains the float propertizes it in such a way:

@property (assign) float* theFloat;

There is also floatLength:

@property (assign) int floatLength;

And has this method, which seems to indicate that the float is of variable length (?):

- (void) copyFloat:(float*)theF ofLength:(int)len
{
    float *floatcopy = malloc(len*sizeof(float));
    memcpy(floatcopy, theF, len*sizeof(float));
    self.theFloat = floatcopy;
}

Answer 1

The address in memory where the float is stored is given by : (int)theFloat: 71411232 You probably want to use something like :

NSLog(@"theFloat = %f", (*record.theFloat));

Which will dereference the pointer and give you the actual data.

Answer 2

Your field, theFloat, is not a primitive type but a pointer. float* means it is a pointer to a float. You need to dereference the field in order to get it's value.

Use *theFloat to get the actual value.

Also, I suggest you review your format specifiers.

http://developer.apple.com/mac/library/documentation/cocoa/Conceptual/Strings/Articles/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265