Number Parsing

Parsing numbers from strings is a basic but common task in many programs; here’s how to do it in Go.

package main

import (
    "fmt"
    "strconv"
)

func main() {

    // With ParseFloat, this 64 tells how many bits of precision to parse.
    f, _ := strconv.ParseFloat("1.234", 64)
    fmt.Println(f)

    // For ParseInt, the 0 means infer the base from the string.
    // 64 requires that the result fit in 64 bits.
    i, _ := strconv.ParseInt("123", 0, 64)
    fmt.Println(i)

    // ParseInt will recognize hex-formatted numbers.
    d, _ := strconv.ParseInt("0x1c8", 0, 64)
    fmt.Println(d)

    // A ParseUint is also available.
    u, _ := strconv.ParseUint("789", 0, 64)
    fmt.Println(u)

    // Atoi is a convenience function for basic base-10 int parsing.
    k, _ := strconv.Atoi("135")
    fmt.Println(k)

    // Parse functions return an error on bad input.
    _, e := strconv.Atoi("wat")
    fmt.Println(e)
}

$ go run number-parsing.go 
1.234
123
456
789
135
strconv.ParseInt: parsing "wat": invalid syntax