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strconv.Atoi() throwing error when given a string

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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 } 
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dead beef Avatar asked Apr 29 '16 00:04

dead beef


2 Answers

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) 
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Bayta Darell Avatar answered Sep 30 '22 08:09

Bayta Darell


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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Thirumalai Parthasarathi Avatar answered Sep 30 '22 09:09

Thirumalai Parthasarathi