从NSCFString到NSNumber的对话

Question

I've below numbers which are stored as NSCFString into SQLite

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These numbers converts perfectly

475602307163925662

1529228456639250520

I am converting these like , (NSNumber *) [myDictionary valueForKey:@"stringData"]; and its working perfectly

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These numbers couldn't converts perfectly

14154269406789154303

13207084142614401684

12870871772958895646

I want to convert these NSCFString into NSNumber. I try using below code and google it but dont get exact solution as I want. Any help would be appriciated.

NSNumberFormatter *f=[[NSNumberFormatter alloc] init];
[f setNumberStyle:NSNumberFormatterDecimalStyle];
NSNumber *myNumber=[f numberFromString:[myDictionary valueForKey:@"stringData"]];
[f release];

but it converts my number something like 9.45214212452152

I tried some other way as well but its also not working well.

NSNumber *myNumber=[NSNumber numberWithLong:[myDictionary valueForKey:@"stringData"]];

Answer 1

Casting an object as another object (aka (NSNumber *) ) does not "convert" it. It just promises the compiler that you're working with an object of that class which you aren't .

The reason why some numbers are totally failing is because they're too large to fit in the standard int/float/long sizes. Instead of NSNumber , use NSDecimalNumber - a subclass of NSNumber (so you can still use all of the NSNumber methods as well). It's specifically designed to handle large numbers:

NSDecimalNumber *number = [NSDecimalNumber decimalNumberWithString:<your string object>];