Go Formatting Verbs

Welcome to The Coding College! Formatting verbs in Go (Golang) are essential for creating structured and dynamic output. By using verbs with the fmt package, you can customize how data is displayed, ensuring precision and clarity.

What Are Formatting Verbs?

Formatting verbs are placeholders used in fmt functions like fmt.Printf and fmt.Sprintf. They specify how values should be formatted for output.

Commonly Used Formatting Verbs

1. General Verbs

These verbs apply to most data types:

2. Integer Verbs

Use these for formatting integers:

3. Floating-Point and Complex Verbs

These are used for floating-point numbers and complex values:

4. String and Byte Slice Verbs

These apply to strings and byte slices:

5. Pointer Verbs

Pointers can also be formatted:

Controlling Width and Alignment

You can specify field width and alignment with numbers in the format string:

1. Width

• Minimum width for a field:

fmt.Printf("%10s", "Go") // Right-align

Output:

        Go

2. Left-Align

• Use - to left-align:

fmt.Printf("%-10s is great!", "Go")

Output:

Go         is great!

3. Width and Precision for Floats

• Specify both width and precision:

fmt.Printf("%10.2f", 3.14159)

Output:

      3.14

Practical Examples

Example 1: Format Various Types

package main

import "fmt"

func main() {
    var name = "Alice"
    var age = 30
    var height = 5.75

    fmt.Printf("Name: %s, Age: %d, Height: %.2f\n", name, age, height)
}

Output:

Name: Alice, Age: 30, Height: 5.75

Example 2: Inspect Type and Value

package main

import "fmt"

func main() {
    var x = 42
    fmt.Printf("Value: %v, Type: %T\n", x, x)
}

Output:

Value: 42, Type: int

Example 3: Enumerate Integers

package main

import "fmt"

func main() {
    for i := 1; i <= 5; i++ {
        fmt.Printf("Decimal: %d, Binary: %b, Hex: %x\n", i, i, i)
    }
}

Output:

Decimal: 1, Binary: 1, Hex: 1
Decimal: 2, Binary: 10, Hex: 2
Decimal: 3, Binary: 11, Hex: 3
Decimal: 4, Binary: 100, Hex: 4
Decimal: 5, Binary: 101, Hex: 5

Best Practices

1. Choose the Right Verb: Ensure the verb matches the data type.
2. Use Precision for Floats: Avoid unnecessary decimals with %.nf.
3. Combine Verbs for Structs: Use %+v for detailed output of structs.
4. Inspect Types with %T: Debug by checking variable types.

Conclusion

Formatting verbs in Go provide powerful tools for customizing output, making your programs more user-friendly and professional. By mastering these verbs, you can write better code that communicates effectively.