英文:
Getting syntax error: unexpected comma, expecting {
问题
我在尝试使用golang的break和continue，我写了以下代码：
func main() {
for k, i := 0, 0; i < 10; i++, k++ {
for j := 0; j < 10; j++ {
if k == 10 {
fmt.Println("Value of k is:", k)
break
}
}
}
}
在第一个for循环的行上，我遇到了以下语法错误：
语法错误：意外的逗号，期望 {
我不知道正确的语法应该是什么样的。
英文:
I was trying for, break and continue in golang and I did this...
func main() {
for k, i := 0, 0; i < 10; i++, k++ {
for j := 0; j < 10; j++ {
if k == 10 {
fmt.Println("Value of k is:", k)
break
}
}
}
}
I am getting this syntax error on line of the 1st for:
> syntax error: unexpected comma, expecting {
I don't know, how the correct syntax should be instead.
答案1
得分: 12
你需要同时初始化k和i：for k, i := 0, 0;
此外，你不能使用i++, k++，而是需要使用i, k = i+1, k+1
参考Effective Go中的说明：
最后，Go语言没有逗号运算符，
++和--是语句而不是表达式。因此，如果你想在for循环中使用多个变量，你应该使用并行赋值（尽管这样就不能使用++和--）。// 反转一个切片
for i, j := 0, len(a)-1; i < j; i, j = i+1, j-1 { a[i], a[j] = a[j], a[i] }
func main() {
for k, i := 0, 0; i < 10; i, k = i+1, k+1 {
for j := 0; j < 10; j++ {
if k == 10 {
fmt.Println("k的值为：", k)
break
}
}
}
}
注意，这样k永远不会达到10，所以你的消息不会被打印出来。你同时增加了i和k，而外层循环停在i < 10（因此也是k < 10）。
英文:
You need to initialize both k and i: for k, i := 0, 0;
Additionally you can't do: i++, k++. Instead you have to do i, k = i+1, k+1
See this reference in Effective Go:
> Finally, Go has no comma operator and ++ and -- are statements not
> expressions. Thus if you want to run multiple variables in a for you
> should use parallel assignment (although that precludes ++ and --).
>
> // Reverse a
> for i, j := 0, len(a)-1; i < j; i, j = i+1, j-1 {
> a[i], a[j] = a[j], a[i] }
func main() {
for k, i := 0, 0; i < 10; i, k = i+1, k+1 {
for j := 0; j < 10; j++ {
if k == 10 {
fmt.Println("Value of k is:", k)
break
}
}
}
}
Note also that k never reaches 10 like this, so your message won't print. You are incrementing i & k at the same time and the outer loop stops at i < 10 (and thus k < 10).
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