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objective-cmacosnsscanner

NSScaner - can not get HexFloatValue?

I'm trying using the following code:

float fValue = 0;
NSScanner *scanner = [NSScanner scannerWithString:@"0x41CC8937"];
[scanner scanHexFloat:&fValue];

Hex 0x41CC8937 = float 25.567.

But I'm getting fValue = 0x4E839912 (float 1103923456.000000), Why?

Solution

  • scanHexFloat expects a "Hexadecimal Floating-Point Constant", you can read more about that here: http://www.exploringbinary.com/hexadecimal-floating-point-constants/.

    What you have it the binary representation of the 32-bit floating point value. You can read that with scanHexInt and use a union to interpret the number as float:

    union {
    float fValue;
    unsigned int iValue;
} u;
NSScanner *scanner = [NSScanner scannerWithString:@"0x41CC8937"];
[scanner scanHexInt:&u.iValue];
NSLog(@"%f", u.fValue);

    Output: 25.566999