Go中奇怪的编译器错误

Question

When I run the following code (it's supposed to reverse the contents of a string), I get strange errors from the compiler.

package main
import "fmt"
func main(){

    argString := "I am a string"
    arrayPointer := len(argString)
    outputString := "string"

    for arrayPointer >= 0 ; arrayPointer-- {
        outputString := fmt.Sprintf("%s%s", outputString, argString[arrayPointer])
    }
}

It throws the following errors:

prog.go:9: syntax error: missing { after for clause
prog.go:12: syntax error: unexpected }
[process exited with non-zero status]

I've used this syntax before (unless I'm missing something), and I've never seen errors from it. What am I missing?

Answer 1

From the spec, there are three forms for a for statement:

1. a single conditional expression
2. the three statement version giving an init statement, condition and post statement
3. a range clause.

Your statement doesn't match any of these. Most likely the compiler has decided that you are using (1), and errors out when there isn't a { after arrayPointer >= 0. You can fix this by changing to case (2):

for ; arrayPointer >= 0 ; arrayPointer-- {

(or using the arrayPointer initialisation statement as the first part of the for statement).