exercism/go/election-day/HINTS.md

Hints

General

• *T can be used to declared variables that are pointers to some type T, e.g var i *int declares a variable i that is a pointer to an int
• You can get a pointer for a variable (its memory address) by using the & operator, e.g mypointer := &anIntVariable.
• You can get the value stored in a pointer by using the * operator on a pointer, eg. var i int = *aPointerToInt. This is called dereferencing the pointer.
• You check if a pointer is not nil before dereferencing it. Attempting to dereference a nil pointer will give you a runtime error.
• If you are unsure how pointers work, try reading Tour of Go: Pointers or Go by Example: Pointers

1. Create a vote counter

• You need to create a pointer to an int, in other words, a *int.
• You can use the & operator on a variable to create a pointer to it, e.g &myInt
• You can create a pointer to a new variable defined by you or you can use the variable of the function argument

2. Get number of votes from a counter

• You can use the * operator on a pointer to dereference it and get its value, e.g *myPointer
• Dereferencing nil pointers will give you a runtime error. Always make sure a pointer is not nil before dereferencing it.

3. Increment the votes of a counter

• If you have a pointer var myPointer *int, you can assign to *myPointer to change the value pointed by myPointer
• To get the current value of the pointer, you need to dereference it using the * operator, or call the function you made in the previous task.

4. Create the election results

• Create a new ElectionResult literal or variable with the fields Name and Votes filled with the values in the arguments of the function.
• You can create a pointer from a variable or literal by using the & operator before the variable name/literal declaration, e.g &myVariable or &ElectionResult{Name: "John", Votes: 1}

5. Announce the results

• Although you are receiving a pointer to an ElectionResult, you can access its fields with the dot . notation, like if it wasn't a pointer!
• Build the message by accessing the Name and Value fields on the struct.
• Even though you are accessing fields from a pointer to a struct, you don't need to do any dereferencing. Go will automatically dereference the pointer for you, like in this example:

result := &ElectionResult{
    Name: "John",
    Votes: 32
}

result.Name // "John" - Go will automatically dereference the pointer
            //          and access the 'Name' field of the dereferenced struct 

6. Vote recounting

• You can think of maps as being pointers already. This means that changes you make to the map inside the function will be visible outside the function.
• To increment the value of a key in a var m map[string]int, you have several options: m["mykey"] = m["mykey"] + 1 , m["mykey"] += 1 or m["mykey"]++