golang constant

A constant in the Go programming language is a value that cannot be modified or changed once it's assigned. Constants are declared using the const keyword followed by the name of the constant, an optional type, and the value.

Here are the steps to declare and use a constant in Go:

1. Start by using the const keyword to declare a constant. For example, const pi = 3.14159 declares a constant named pi with a value of 3.14159.

2. Optionally, you can specify the type of the constant explicitly. For example, const name string = "John" declares a constant named name with the value "John" and the type string.

3. Constants can also be declared together in a group. For example:

const (
    apple = "fruit"
    banana = "fruit"
    cat = "animal"
)

In this example, apple and banana are constants of type string with the value "fruit", and cat is a constant of type string with the value "animal".

1. Constants can be used in expressions and assignments just like variables. For example:

const radius = 5
area := pi  radius  radius

In this example, the constant radius is used to calculate the area of a circle by multiplying it with the constant pi.

1. Constants can also be used as part of switch cases. For example:

const (
    Monday = 1
    Tuesday = 2
    Wednesday = 3
    // ...
)

func main() {
    day := Monday

    switch day {
    case Monday:
        fmt.Println("It's Monday!")
    case Tuesday:
        fmt.Println("It's Tuesday!")
    case Wednesday:
        fmt.Println("It's Wednesday!")
    // ...
    }
}

In this example, the constants Monday, Tuesday, and Wednesday are used in a switch statement to determine the day of the week.

That's it! These are the basic steps to declare and use constants in the Go programming language. Constants provide a way to define values that should not be changed throughout the execution of the program.