Instructions

Test suite

Solution

Convert a number to a string, the contents of which depend on the number's factors.

- If the number has 3 as a factor, output 'Pling'.
- If the number has 5 as a factor, output 'Plang'.
- If the number has 7 as a factor, output 'Plong'.
- If the number does not have 3, 5, or 7 as a factor, just pass the number's digits straight through.

- 28's factors are 1, 2, 4,
**7**, 14, 28.- In raindrop-speak, this would be a simple "Plong".

- 30's factors are 1, 2,
**3**,**5**, 6, 10, 15, 30.- In raindrop-speak, this would be a "PlingPlang".

- 34 has four factors: 1, 2, 17, and 34.
- In raindrop-speak, this would be "34".

This may be the first Go track exercise you encounter without a stub: a
pre-existing `raindrops.go`

file for your solution. You may not see stubs in
the future and should begin to get comfortable with creating your own Go files
for your solutions.

One way to figure out what the function signature(s) you would need is to look at the corresponding *_test.go file. It will show you what the package level functions(s) should be that the test will use to verify the solution.

To run the tests run the command `go test`

from within the exercise directory.

If the test suite contains benchmarks, you can run these with the `--bench`

and `--benchmem`

flags:

```
go test -v --bench . --benchmem
```

Keep in mind that each reviewer will run benchmarks on a different machine, with different specs, so the results from these benchmark tests may vary.

For more detailed information about the Go track, including how to get help if you're having trouble, please visit the exercism.io Go language page.

A variation on a famous interview question intended to weed out potential candidates. http://jumpstartlab.com

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

```
package raindrops
// Source: exercism/problem-specifications
// Commit: 99de15d raindrops: apply "input" policy
// Problem Specifications Version: 1.1.0
var tests = []struct {
input int
expected string
}{
{1, "1"},
{3, "Pling"},
{5, "Plang"},
{7, "Plong"},
{6, "Pling"},
{8, "8"},
{9, "Pling"},
{10, "Plang"},
{14, "Plong"},
{15, "PlingPlang"},
{21, "PlingPlong"},
{25, "Plang"},
{27, "Pling"},
{35, "PlangPlong"},
{49, "Plong"},
{52, "52"},
{105, "PlingPlangPlong"},
{3125, "Plang"},
}
```

```
package raindrops
import "testing"
func TestConvert(t *testing.T) {
for _, test := range tests {
if actual := Convert(test.input); actual != test.expected {
t.Errorf("Convert(%d) = %q, expected %q.",
test.input, actual, test.expected)
}
}
}
func BenchmarkConvert(b *testing.B) {
for i := 0; i < b.N; i++ {
for _, test := range tests {
Convert(test.input)
}
}
}
```

```
package raindrops
import "strconv"
// Convert turns a number into a string, following the "raindrop" rule:
// - If the number has 3 as a factor, output 'Pling'.
// - If the number has 5 as a factor, output 'Plang'.
// - If the number has 7 as a factor, output 'Plong'.
// - If the number does not have 3, 5, or 7 as a factor,
// just return it (as a string).
func Convert(n int) string {
divisibleBy3 := n%3 == 0
divisibleBy5 := n%5 == 0
divisibleBy7 := n%7 == 0
if !divisibleBy3 && !divisibleBy5 && !divisibleBy7 {
return strconv.Itoa(n)
}
res := ""
if divisibleBy3 {
res += "Pling"
}
if divisibleBy5 {
res += "Plang"
}
if divisibleBy7 {
res += "Plong"
}
return res
}
```

A huge amount can be learned from reading other people’s code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

- What compromises have been made?
- Are there new concepts here that you could read more about to improve your understanding?

Level up your programming skills with 3,285 exercises across 51 languages, and insightful discussion with our volunteer team of welcoming mentors.
Exercism is
**100% free forever**.

## Community comments