Issue converting string to double

[tallybear]

Here's what I'm doing...

I have some XML that I'm parsing out. One of these elements is a rate for a campground. The parsed string (just an example) comes out to something like 24.0000. It always has 4 decimal places. I'm trying to convert this to a double and truncate the last 2 decimal places. I've tried several different things, but none of them have worked. Does anyone have any experience with this?

[RLScott]

Originally Posted by tallybear

Here's what I'm doing...

I have some XML that I'm parsing out. One of these elements is a rate for a campground. The parsed string (just an example) comes out to something like 24.0000. It always has 4 decimal places. I'm trying to convert this to a double and truncate the last 2 decimal places. I've tried several different things, but none of them have worked. Does anyone have any experience with this?

Truncating the last two decimal places is something that is applicable to strings that are made from doubles, not doubles that are made from strings. A double has no particular number of decimal places.

Since you already have the string form to begun with, you could just truncate the string first by making another string that leaves off the last two characters. Then convert that string to a double, is that what you mean?

[tallybear]

Originally Posted by RLScott

Truncating the last two decimal places is something that is applicable to strings that are made from doubles, not doubles that are made from strings. A double has no particular number of decimal places.

Since you already have the string form to begun with, you could just truncate the string first by making another string that leaves off the last two characters. Then convert that string to a double, is that what you mean?

I found what I was looking for:

double num1 = [string doubleValue];
NSString *parsedText = [[NSString alloc] initWithFormat:@"%0.2f", num1];

Thanks anyway.

[RickSDK]

by the way, you can avoid the alloc by using StringWithFormat:

NSString *parsedText = [NSString StringWithFormat:@"%0.2f", num1];

[Duncan C]

Originally Posted by RickSDK

by the way, you can avoid the alloc by using StringWithFormat:

NSString *parsedText = [NSString StringWithFormat:@"%0.2f", num1];

To say you can "avoid the alloc" is a little misleading.

stringWithFormat is a "convenience method." It creates and returns an autoreleased string object. It would be more accurate to say that you can avoid having to release the string after using it.

Internally, the implementation of stringWithFormat probably looks something like this:

+ (id)stringWithFormat:(NSString *)format, ...
{
  result = [NSString alloc] initWithFormat: format, ...];
  return [result autorelease];
}

(It won't be exactly like that, because there's some magic I don't remember that you have to do to pass the variable number of arguments on to initWithFormat, but you get the idea.)

The OPs code, using initWithFormat, had a memory leak unless he was using ARC.

In manual reference counting, after you alloc/init and object, you have to release it when you are done with it.

stringWithFormat returns an autoreleased string, so you don't have to release it.