Multiply and divide

Add multiply, divide and zero check.

Multiplication and division

Multiplication is as simple as the others. Division, however, must handle dividing by zero: dividing a float64 by zero doesn't error but produces +Inf, which shows the user a meaningless result. So the divisor is checked and an error returned:

func bol(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("sıfıra bölünemez")
    }
    return a / b, nil
}

Checking the error

When calling a function that returns an error, check the error first and only use the result if there is none:

sonuc, err := bol(10, 0)
if err != nil {
    fmt.Println("hata:", err)
    return
}
fmt.Println(sonuc)

This "error first" pattern shows up everywhere in Go.

Exercise Safe division

Write the bol(a, b float64) (float64, error) function. Print the result of bol(9, 2) and the error from bol(1, 0) on separate lines.

Show example solution

package main

import (
    "errors"
    "fmt"
)

func bol(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("sıfıra bölünemez")
    }
    return a / b, nil
}

func main() {
    s, _ := bol(9, 2)
    fmt.Println(s)
    _, err := bol(1, 0)
    fmt.Println(err)
}

Test yourself

What does <code>5.0 / 0.0</code> produce in Go?
- A panic
- 0
- A compile error
- +Inf
Show answer

+Inf — Decimal division follows IEEE 754 and gives infinity; dividing an integer by zero panics.

Zero check

if b ____ 0 {
    return 0, errors.New("sıfıra bölünemez")
}

Show answer

if b == 0 {
    return 0, errors.New("sıfıra bölünemez")
}

Operation and result

carp(3, 4)

12
bol(9, 2)

4.5, nil
bol(1, 0)

0, error
5.0 / 0.0

+Inf

Next lesson: Command-line menu

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