Menu
I am wondering why the following piece of code is not working:
package main
import (
"fmt"
)
func main() {
for i := 0; i < 10000; i++ {
var randomString = fmt.Sprintf("a%sa\n", "test")
}
fmt.Printf("Made 10000 random strings like", randomString);
}
I've stripped some unrelevant code (as this is obviously not really random).
The issue i'm having is that just under the for-loop, "randomString" is undefined.
I've tried setting it using randomString := fmt.Sprintf() and with the var you've seen above.
I'm quite sure this is a scoping issue (the randomString variable is not in the scope outside of the for-loop), but as a PHP / JS developer, i'm not used to this and would say that variable is also available after the for loop.
How can I access that variable from that point? Basically just displaying the last generated string.
756
If the variable is declared outside the loop, then it has the global scope as it can be used through-out the function and inside of the loop too. If the variable is declared inside the loop, then the scope is only valid inside the loop and if used outside the loop will give an error.
If you want to access every element of randAd outside the for loop try like this var randAd = []; to initialize it as an array. You can easily access it after your for loop but If you use it as a simple variable var randAd; then you'll get the last variable always (it overwrites).
In terms of readability and maintainability you should prefer to define the variable inside the loop.
You can access all global variables with globals() Enclosed: In the outer function, if this is a nested function. Local: Within the current function. You can access all local variables with locals() .
See the relevant section from the spec: Declarations and scope:
The scope of a constant or variable identifier declared inside a function begins at the end of the ConstSpec or VarSpec (ShortVarDecl for short variable declarations) and ends at the end of the innermost containing block.
Define it in the scope in which you want to access it: before the for (in the scope of the main() function).
Also note that fmt.Sprintf() requires an additional parameter besides the ones to be printed: a format string. Either provide a format string (e.g. include a %s verb for the randomString parameter) or alternatively you may use fmt.Sprintln().
func main() {
var randomString string
for i := 0; i < 10000; i++ {
randomString = fmt.Sprintf("a%sa\n", "test")
}
fmt.Println("Made 10000 random strings like", randomString)
}
Output:
Made 10000 random strings like atesta
Try it on the Go Playground.
181
This is scoping issue, in Go the scope of randomString is the loop body, in JS it would be the whole function. Scoping rules differ in the different languages.
Check the Go spec:
https://golang.org/ref/spec#Declarations_and_scope
27
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
