# Thread: Float and double to binary

1. Member Join Date
Sep 2008
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## Float and double to binary

How do I perform float and doubles to binary. For float I have tried
Java Code:
`Integer.toBinaryString(Float.floatToRawIntBits(value));`
But the answer doesnt seem to be right. When I input a value '1' into the above function, I get an output
Java Code:
`111111100000000000000000000000`
which is definitely wrong.  Reply With Quote

2. ## was value an int? Does java convert it to an int to float to match the parms for that method?
The API doc for that method says:
Bit 31 (the bit that is selected by the mask 0x80000000) represents the sign of the floating-point number. Bits 30-23 (the bits that are selected by the mask 0x7f800000) represent the exponent. Bits 22-0 (the bits that are selected by the mask 0x007fffff) represent the significand (sometimes called the mantissa) of the floating-point number.  Reply With Quote

3. ## To pick apart/interpret the value returned from the Float.floatToIntBits method see its description in the Method Detail section of the Float class api.
Also, a couple of resouce links:
IEEE 754-1985
IEEE 754 Converter
Java Code:
```public class Test {
public static void main(String[] args) {
float f = -118.625f;
int intBits = Float.floatToIntBits(f);
int rawIntBits = Float.floatToRawIntBits(f);
System.out.printf("f = %f  intBits = %d  " +
"rawIntBits = %d%n", f, intBits, rawIntBits);
float toFloat = Float.intBitsToFloat(intBits);
System.out.printf("toFloat = %f%n", toFloat);

int sign     = intBits & 0x80000000;
int exponent = intBits & 0x7f800000;
int mantissa = intBits & 0x007fffff;
System.out.printf("sign = %d  exponent = %d  mantissa = %d%n",
sign, exponent, mantissa);

String binarySign = Integer.toBinaryString(sign);
String binaryExponent = Integer.toBinaryString(exponent);
String binaryMantissa = Integer.toBinaryString(mantissa);
System.out.printf("binarySign     = %s%nbinaryExponent = %s%n" +
"binaryMantissa = %s%n", binarySign,
binaryExponent, binaryMantissa);
}
}```  Reply With Quote

4. Member Join Date
Sep 2008
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## thanx...
thats what I wanted to know. How to handle the mantissa?

thanx again  Reply With Quote

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