英文:
strconv.Atoi() throwing error when given a string
问题
尝试使用strconv对通过URL传递的变量（名为times的GET变量）进行转换时，GoLang在编译时出现以下错误：
> multiple-value strconv.Atoi() in a single-value context
然而，当我使用reflect.TypeOf时，我得到的类型是string，根据我的理解，这是正确的参数类型。
我已经尝试解决这个问题几个小时了。我对Go语言还很陌生，对这个问题感到非常沮丧。最后我决定寻求帮助。任何反馈都将不胜感激。
func numbers(w http.ResponseWriter, req *http.Request) {
fmt.Println("GET params were:", req.URL.Query());
times := req.URL.Query()["times"][0]
time := strconv.Atoi(times)
reflect.TypeOf(req.URL.Query()["times"][0]) // 返回string类型
}
英文:
When trying to use strconv on a variable passed via URL(GET variable named times), GoLang fails on compilation stating the following:
> multiple-value strconv.Atoi() in a single-value context
However, when I do reflect.TypeOf I get string as the type, which to my understanding is the correct type of argument.
I have been trying to fix this issue for several hours. I'm new to go and have become pretty frustrated with this problem. I finally decided to ask for help. Any feedback would be appreciated.
func numbers(w http.ResponseWriter, req *http.Request) {
fmt.Println("GET params were:", req.URL.Query());
times := req.URL.Query()["times"][0]
time := strconv.Atoi(times)
reflect.TypeOf(req.URL.Query()["times"][0]) // returns string
}
答案1
得分: 69
错误提示告诉你，strconv.Atoi 的两个返回值（int 和 error）在单值上下文中被使用（赋值给 time）。将代码更改为：
time, err := strconv.Atoi(times)
if err != nil {
// 在这里添加处理错误的代码！
}
使用空白标识符来忽略 error 返回值：
time, _ := strconv.Atoi(times)
英文:
The error is telling you that the two return values from strconv.Atoi (int and error) are used in a single value context (the assignment to time). Change the code to:
time, err := strconv.Atoi(times)
if err != nil {
// Add code here to handle the error!
}
Use the blank identifier to ignore the error return value:
time, _ := strconv.Atoi(times)
答案2
得分: 12
虽然这个问题已经有答案了，而且问题也相当久远，但我觉得补充一下接受的答案会很好。
当一个函数返回多个值时，如果其中任何一个值不需要，可以使用空白标识符 _ 来丢弃它们，如下所示：
num, _ := strconv.Atoi(numAsString)
这将把转换后的数字存储在 num 中，但通过将其赋值给空白标识符来丢弃错误。
但请注意，一旦一个值被赋给 _，就不能再引用它了。也就是说：
num, _ := strconv.Atoi(numAsString)
fmt.Println(_) // 无法编译，不能引用 _。
英文:
Although this has been answered and the question is quite old, I thought it would be nice to complement the accepted answer.
When a function returns multiple values as in the question, if any of the value is not needed then they can be discarded by using the blank identifier _ as in the following.
num, _ := strconv.Atoi(numAsString)
This would store the converted number in num but discard the error by assigning it to the blank identifier.
But do note that once a value is assigned to _ it cannot be referenced again. i.e.
num, _ := strconv.Atoi(numAsString)
fmt.Println(_) // won't compile. cannot reference _
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