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120 lines
2.6 KiB
Markdown
120 lines
2.6 KiB
Markdown
---
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title: "Learning Go: Day Three"
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date: 2024-05-03T08:00:00.0Z
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tags:
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- learning
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- go
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excerpt: "For my third day of learning Go, I'm going to take a look at some control structures"
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---
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Over the last two days I've learned how to [setup and create a Go project](/post/learning-go-day-1/), and then [how to organise code into packages](/post/learning-go-day-2). I realise I've skipped a crucial step there, though, which is learning how to deal with control structures.
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By control structures, I'm referring to things like `for-` loops, `if` statements, etc. You know, the things that make the software do things beyond just multiplying 2 by 5.
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## For-loops
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The old trusty workhorse of any programming language. These seem pretty straightforward in Go, similar to most other languages:
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```go
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// maths.go
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// Calculate val to the n'th power
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func Pow(val, n int) int {
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for i:= 1; i < n; i++ {
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val *= val
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}
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return val
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}
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// main.go
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func main() {
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four_squared := maths.Pow(4, 2)
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fmt.Printf("4^2 = %d\n", four_squared)
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}
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```
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Cool, this worked. I have successfully reinvented a small wheel[^1].
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## Do-While
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The _other_ trusty workhorse! Most languages have some form of this construct that says something like:
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```
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while statement is true:
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do something
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```
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But not Go, apparently! Or at least, not explicitly. In for-loops, the first and last arguments - defining a variable and performing an operation on it - are totally optional, so a while loop is just a for-loop[^2]:
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```go
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// maths.go
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func Mod(a, b int) int {
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remainder := a
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for remainder >= b {
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remainder -= b
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}
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return remainder
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}
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```
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## If-else-then
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The third trusty workhorseman of the Gopocalypse[^3]. Basic if-statements are pretty straightforward:
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```go
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// maths.go
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func Divide(a, b int) int {
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if a == 0 {
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return 0
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}
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if b == 0 {
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return 0
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}
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return a / b
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}
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```
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Which could be cleaned up to use else-if:
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```go
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// maths.go
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func Divide(a, b int) int {
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if a == 0 {
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return 0
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} else if b == 0 {
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return 0
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}
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}
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```
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You can also add variable declarations to if-statements, which are then only accessible inside the blocks:
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```go
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// maths.go
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func Min(a, b int) int {
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if v := a - b; v > 0 {
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return b
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} else {
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return a
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}
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}
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```
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Okay, so that's covered most of the control structures off the top of my head. On my to-do list for the next couple of days are: working with arrays, and testing.
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[^1]: This particular wheel is a lot slower than the original wheel, but hey, I'm learning
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[^2]: Yes, yes, I know that's actually the case in many languages and `while` is just syntactic sugar
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[^3]: I'm sorry.
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