Idiomatic way to use strconv.ParseInt with ints

Question

I end up writing code like this. I need a regular int (for some other function call), but parseInt only produces 64 bit ints:

i64, err := strconv.ParseInt(s, 10, 0)
if err != nil {
    fmt.Println("parsing failed for", s)
}
i := int(i64)

http://play.golang.org/p/_efRm7yp3o

Is there a way to avoid the extra cast? Or a way to make this more idiomatic?

Answer 1

You can use strconv.Atoi which wraps strconv.ParseInt in a way you want.

Answer 2

Use the bitSize parameter of strconv.ParseInt

package main

import (
        "fmt"
        "strconv"
)

// 32 or 64 depending on platform
const IntBits = 1 << (^uint(0)>>32&1 + ^uint(0)>>16&1 + ^uint(0)>>8&1 + 3)

func printInt(i int) {
        fmt.Println(i)
}

func main() {
        s := "-123123112323231231"
        i64, err := strconv.ParseInt(s, 10, IntBits)
        if err != nil {
                fmt.Println("parsing failed for ", s)
        }
        i := int(i64)
        printInt(i)

        i64, err = strconv.ParseInt(s, 10, 32)
        if err != nil {
                fmt.Println("parsing failed for ", s)
        }
        i = int(i64)
        printInt(i)
}

Playground

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Output

-123123112323231231
parsing failed for  -123123112323231231
-2147483648