Golang：如何将float64货币表示形式转换为最小面额？ （乘以100并不适用于所有货币）

Question

I'm dealing with a float64 representation of money. For example, 2.9 for usd represents $2.90, so if I need to convert this to the lowest denomination for the currency, I just multiple by 100 (2.9*100= 290 cents).

This works with most major currencies. However, in Japan, for example, the float64 representation will not have a decimal because Yen is already the lowest representation. If I get float64(290) Yen, multiplying by 100 would give an excess number of Yen if I'm trying to obtain the lowest denomination - it should stay as is.

What's the best way to handle this besides special casing when to multiply by 100 for certain currencies?

EDIT: the two pieces of information I have are the float representation and the ISO currency code.

Answer 1

Do not use floating-point numbers for money. Floating-point numbers are an approximation. float64 (the set of all IEEE-754 64-bit floating-point numbers) conforms to the IEEE Standard for Floating-Point Arithmetic (IEEE 754).

Wikipedia: IEEE 754

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Use the ISO 4217 standard to determine the minor currency unit exponent. It is 2 (10² = 100) for most currencies and 0 (10⁰ = 1) for the Japanese Yen (JPY).

Wikipedia: ISO 4217

Current currency & funds code list