I am having trouble understanding your information.
I understand a little of what you say but not all. I understand I am not allowed to do what I did but not everything else . (by the way I don’t understand what I did either 
. I was just playing around)
Can you let me know where you are starting to have difficulty? I can explain things better.
Hi, what is it that’s confusing?
Okay, I will take one thing at a time. What"s the definition of “declares” here?
I think I am like a baby learning to speak. All the language is coming at me but I don’t understand it. I have no background in programmin.
So, first, what does this mean? err := strconv.Atoi(“42”); err == nil
You can think of yourself talking to the Go compiler. It is just a machine and you need to be very specific about everything, and speak exactly its language.
Go is a language that requires every variable to have a specific type. Since the compiler needs to know which type you want a variable to be, naturally, you need to tell it. You do that by declaring the variable. Here is a simple example, similar to what you’ve already seen and used:
var abc int
This declaration tells the compiler that you are using a variable named abc and that it is an integer (actually, an int), rather than some other type (like a string, floating-point number, slice, rune, and so on). Now that the Go compiler knows that, if you make a mistake and try to set abc to another kind of type, or use it as something other than an integer, it will tell you that you have made an error.
I’m thinking that this must seem very complicated to anyone who is just starting as a programmer. Maybe you are asking, “Why is it made so complicated and difficult?” The answer to that is that you have to consider what it’s like to have a program in an untyped language that is thousands (or even hundreds of thousands) of lines long, and then get an error that seems to be telling you that 2 + 3 is “not a number”! Then you have to analyze your (or someone else’s) code to see where a variable was used as an integer when it actually contained a string or something else instead of an integer. In large programs, that’s hard and not fun! Instead of quietly allowing you to dig your own grave, Go’s compiler catches type mismatches during compilation. Then you can fix the problem quickly and easily, and continue creating your program, which is a lot easier, and a lot more fun. I hope that helps.
Years ago I tried learning a little Japanese, and the first part was to learn to write the hiragana alphabet. I had the same feeling! I had to practice writing every character over and over. I felt like I was 5 years old and just learning to write.
Fortunately, any programming language is a lot easier to learn than Japanese. So don’t worry.
About the code snippet, you didn’t get the whole thing. Try this:
if i, err := strconv.Atoi("42"); err == nil { /* statements */ }
This is an example of a more complicated if/then construct. It is equivalent to
i, err := strconv.Atoi("42")
if err == nil { /* statements */ }
Go allows you to insert a statement before the boolean expression of the if statement. It’s just to allow for more concise code. (Personally, I think it’s best to avoid using it, except for very simple cases.)
The first line is like this:
x, y = 1, 2
which sets x to 1 and y to 2. It’s called a tuple assignment. It’s nearly the same as
x = 1
y = 2
But when you have a function that returns multiple values, you have to use a tuple assignment to store those values in variables. So
i, err := strconv.Atoi("42")
results in the string "42" being converted into an int and stored in i, and err will be something other than nil if Atoi() ran into a problem. It’s a good programming practice to always (or at least usually) check for errors and handle them.
Is that what you needed as an explanation?
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This is very helpful, and I saved it to a file
Where should I try if i, err := strconv.Atoi(“42”); err == nil { /* statements */ }
I interpreted it as…https://play.golang.org/p/ClDeIx4_LXA
And thanks for the encoragement. The fact that I am a baby when it comes to learning the Go language does not frustrate me , but is instead exciting and fun! Better than watching a football game on tv!
Just to clarify, those are not entirely equivalent. As I stated in my earlier post, when declaring and assigning in the if statement, variables are local to the if scope, not the surrounding function. So, in the first case it’s wrong to try to use the variables after the if (or if - else if - else) scope, i.e.:
func someFunc() {
if i, err := strconv.Atoi("42"); err == nil {
/*
Some statements should go here.
i and err may be used here.
*/
} else {
// Here i and err are fine too, this is still the if scope.
}
fmt.Println(err) //Wrong, err has not been declared in this scope, this won't compile.
}
On the second case, variables will be local to the function scope, so this is fine:
func someFunc() {
i, err := strconv.Atoi("42")
if err == nil { /* statements */ }
fmt.Println(err) //This is fine, err is well defined here.
}
This is explained at the Go tour, on the section I linked before.
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Thank you guys. I think I’m going to leave this one and go on from here. I’m determined to succeed
This is difficult for me
Maybe reading about scopes first could help a bit: https://en.wikipedia.org/wiki/Scope_(computer_science).
Cool!
This was definitely helpful.
I also bookmarked it.
This maybe something you want to do…https://play.golang.org/p/PigVlVGoycT. In your example you had a typo after the 2. That was the first error. You cant have ; in Go just after the comparison…Second issue was you were trying to compare apples to bananas…x is a variable but its an integer type and not a boolean. Remember that Go is statically typed.
Interesting and cool.
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