Go语言错误处理问题/误解？ [关闭]

Question

Ok so I am using the following code,

err := r.ParseForm()
if err != nil {
    log.Panic(err)
}

var user User

err := decoder.Decode(&user, r.PostForm)
if err != nil {
    log.Panic(err)
}

Now when I try to run this code, I get the following error,

no new variables on left side of :=

Now I know that this is due to using the same variable, in this case err but I have seen lots of examples where this is how other developers deal with error handling?

The way that I have been using is just to use err1 and err2 so I can build the code.

I have been over the docs but there is a lot to take in and must have missed how the err variable is being able to be re-used, or have I completely misunderstood something?

Thanks,

Answer 1

You redeclared the variable err. What you often see is the shorter error handling syntax:

if err := DoSomething(); err != nil {
    // handle
}

Variables declared in control structures and for loops are only visible to that block. So the err declared above can only be seen within the if block.