How to convert hex to float

Question

I have to convert hex, represeneted as strings (e.g. \"0xC40C5253\") to float values (IEEE-754 conversion). I did not manage

Answer 1

First it needs to be stated the bit-length of the input. Since the hex representation has 4 bytes (8 hex digits), it is most likely a float32 (needs clarification from the asker).

You can parse the bytes from the hex representation into an uint32 using strconv.ParseUint(). ParseUint() always returns uint64 which uses 8 bytes in memory so you have to convert it to uint32 which uses 4 bytes just like float32:

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

Now you have the bytes but they are stored in a variable of type uint32 and therefore interpreted as the bytes of an integer. And you want to interpret them as the bytes of a IEEE-754 floating point number, you can use the unsafe package to do that:

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

Output (try it on the Go Playground):

-561.2863

Note:

As JimB noted, for the 2nd part (translating uint32 to float32) the math package has a built-in function math.Float32frombits() which does exactly this under the hood:

f := math.Float32frombits(n2)