# Go Your First (Real) Program

With all the material we have covered so far, we can finally write our first real program. More precisely, we will write a program to convert a temperature from Celsius to Fahrenheit.

## Define the Package name

The first statement in the Go programming starts with `package name`. Here we are using `package main`, which tells the compiler that the package should be compiled as an executable program instead of a shared library.

``package main``

## Import the fmt Package

We need to import the `fmt` package as we are using the `fmt.Printf` function to print the output. Package fmt implements formatted I/O with functions analogous to C's `printf` and `scanf`.

``import "fmt"``

## Define the constant

Later on, we will see how to ask the user for input but for now, we will hard-code the value of the temperature into a `const`.

``const celcius float64 = 21.0``

## Write the formula

The formula to convert a temperature from Celsius to Fahrenheit is:

``const fahrenheit float64 = celcius*9/5 + 32``

Since `celcius` is a floating-point number, we do not need to write `9.0` or `5.0` in the formula.

## Print the output

Finally, we can print the result:

``fmt.Printf("%.2f°C is %.2f°F.\n", celcius, fahrenheit)``

## Your First (Real) Go Program Combining all the Code

All together, the program looks like this:

``````package main

import "fmt"

func main() {
const celcius float64 = 21.0
const fahrenheit float64 = celcius*9/5 + 32

fmt.Printf("%.2f°C is %.2f°F.\n", celcius, fahrenheit)
}``````

Output

``21.00°C is 69.80°F.``