Introduction to the `fmt` Package
The fmt package in Go is essential for formatted I/O operations such as printing and scanning. This package provides the most common operations you're going to use for console output and simple formatted input.
Printing with `fmt`
The `fmt` package offers various functions for printing:
fmt.Print()fmt.Println()fmt.Printf()
Using Print and Println
The simplest functions in the fmt package are Print() and Println(), which print text to the standard output.
package main
import "fmt"
func main() {
fmt.Print("Hello, World!")
fmt.Println("Hello, World!") // This adds a new line at the end
}Formatted Printing with Printf
The Printf function allows for formatted strings using verbs, similar to C's printf:
func main() {
age := 30
name := "John Doe"
fmt.Printf("%s is %d years old.\n", name, age)
}
Formatting Verbs
Some of the most common verbs used with Printf include:
%s- for strings.%d- for integers.%f- for floating-point numbers.%.2f- for formatting floats to 2 decimal points.
func main() {
price := 19.99
discount := 0.15
fmt.Printf("Price: $%.2f\nDiscount: %.0f%%\n", price, discount*100)
}
Reading Input with `fmt`
The fmt package can also read input from users. The primary function for this is Scanln:
func main() {
var name string
var age int
fmt.Print("Enter your name and age: ")
fmt.Scanln(&name, &age)
fmt.Printf("Hello %s, you are %d years old.\n", name, age)
}
Conclusion
The fmt package is a convenient tool in Go for handling basic formatted input and output. It's straightforward for those familiar with formatted I/O from other languages, enabling easy adaptation and productivity.
