How does golang represent money?

In golang, to represent money we can use float64 or decimal library.

1. Use float64 to represent money

In golang, the floating point number type float64 is one of the most commonly used numerical types, and we can use it to represent money. If you only need to do basic calculations and comparisons, using float64 is a good choice. For example:

var price float64 = 19.99
var total float64 = price * 2
fmt.Println(total) // 39.98

In the above example, we declared a float64 type variable price and initialized it to 19.99. Then, we calculated the total price using price * 2 and assigned the result to total. Finally, we print the value of total, which is 39.98.

However, it should be noted that floating point numbers have precision issues. For example:

var price float64 = 0.1
var total float64 = price * 0.2
fmt.Println(total) // 0.020000000000000004

In the above example, we declared a float64 type variable price and initialized it to 0.1. Then, we calculated the total price using price * 0.2 and assigned the result to total. Finally, we print the value of total and the result is 0.020000000000000004. This is caused by the precision problem of floating point numbers, so when dealing with money, it is recommended to use the decimal library with higher precision.

2. Use the decimal library to represent money

golang's decimal library provides higher precision, which can effectively avoid precision problems caused by floating point numbers, thereby better Represents money. For example:

import "github.com/shopspring/decimal"

func main() {
    price := decimal.NewFromFloat(19.99)
    total := price.Mul(decimal.NewFromInt(2))
    fmt.Println(total) // 39.98
}

In the above example, we used the decimal library and quoted its Mul() method to calculate the total price. We also use NewFromFloat() method and NewFromInt() method to create decimal type variables. The value of result is a decimal value, which is equivalent to the numerical precision of 10 to the power of 24, so the accuracy can be guaranteed not to be affected.

Summary

In golang, we can use float64 or decimal library to represent money. If you only need to do basic calculations and comparisons, using float64 is a good choice. However, it is important to note that floating point numbers have precision issues. If higher precision is required, then using the decimal library is a better choice. When dealing with money, pay special attention to accuracy issues to avoid errors due to accuracy issues.

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