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course/6-errors/exercises/2-formatting_strings/readme.md

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+# Formatting strings review
+
+A convenient way to format strings in Go is by using the standard library's [fmt.Sprintf()](https://pkg.go.dev/fmt#example-Sprintf) function. It's a string interpolation function, similar to JavaScript's built-in template literals. The `%v` substring uses the type's default formatting, which is often what you want.
+
+### Default values
+
+```go
+const name = "Kim"
+const age = 22
+s := fmt.Sprintf("%v is %v years old.", name, age)
+// s = "Kim is 22 years old."
+```
+
+The equivalent JavaScript code:
+
+```js
+const name = 'Kim'
+const age = 22
+s = `${name} is ${age} years old.`
+// s = "Kim is 22 years old."
+```
+
+### Rounding floats
+
+```go
+fmt.Printf("I am %f years old", 10.523)
+// I am 10.523000 years old
+
+// The ".2" rounds the number to 2 decimal places
+fmt.Printf("I am %.2f years old", 10.523)
+// I am 10.53 years old
+```
+
+## Assignment
+
+We need better error logs for our backend developers to help them debug their code.
+
+Complete the `getSMSErrorString()` function. It should return a string with this format:
+
+```
+SMS that costs $COST to be sent to 'RECIPIENT' can not be sent
+```
+
+* `COST` is the cost of the SMS, always showing the price formatted to 2 decimal places.
+* `RECIPIENT` is the stringified representation of the recipient's phone number
+
+*Be sure to include the $ symbol and the single quotes*