How Can I Convert Hex Strings to IEEE-754 Floating-Point Values in Go?

Converting Hex Strings to Float Values in IEEE-754

Despite using the strconv.ParseFloat function, converting hex strings to floating-point values can pose a challenge. This article explores alternative methods to achieve this conversion using the strconv.ParseUint and unsafe packages.

Bit-Length Clarification

Before proceeding with the conversion, it's crucial to determine the bit-length of the input hex string. As mentioned in the question, the provided hex representation has eight digits, indicating a potential float32 data type. However, to ensure accuracy, it's best to clarify this with the questioner.

Using strconv.ParseUint

To parse the bytes from the hex string, strconv.ParseUint can be employed. However, since it returns a uint64 which occupies eight bytes in memory, it must be converted to a uint32 to match the four-byte structure of float32.

s := "C40C5253"
n, err := strconv.ParseUint(s, 16, 32)
if err != nil {
    panic(err)
}
n2 = uint32(n)

Interpreting Bytes as IEEE-754 Floating Point

Now that the bytes are stored in n2 as a uint32, they need to be interpreted as bytes of an IEEE-754 floating-point number. The unsafe package provides a way to access and manipulate memory pointers, allowing us to create a float32 from the uint32 bytes.

f := *(*float32)(unsafe.Pointer(&n2))

Alternative Method Using math.Float32frombits

The math package includes a built-in function specifically designed for this purpose: math.Float32frombits. It directly translates a uint32 value into a float32, offering a more straightforward approach.

f := math.Float32frombits(n2)

Output

Using either method, the sample hex string provided in the question converts to -561.2863 when interpreted as a float32. Testing this solution on the Go Playground can further demonstrate its functionality.

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