Go Your First (Real) Program

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.