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String Formatting

This Go code demonstrates the usage of the fmt package for formatted printing and string formatting. Let's go through the code with inline comments and explanations:
// Importing necessary packages.
import (
"fmt"
"os"
)
// Defining a custom type 'point' with two integer fields.
type point struct {
x, y int
}
// The main function, where the execution of the program begins.
func main() {
// Creating an instance of the 'point' struct.
p := point{1, 2}
// Printing the struct 'p' using different format specifiers.
fmt.Printf("struct1: %v\n", p) // Default format.
fmt.Printf("struct2: %+v\n", p) // Adds field names.
fmt.Printf("struct3: %#v\n", p) // Adds Go syntax representation.
// Printing the type of 'p'.
fmt.Printf("type: %T\n", p)
// Printing a boolean value.
fmt.Printf("bool: %t\n", true)
// Printing an integer value.
fmt.Printf("int: %d\n", 123)
// Printing an integer in binary format.
fmt.Printf("bin: %b\n", 14)
// Printing a character using its ASCII value.
fmt.Printf("char: %c\n", 33)
// Printing an integer in hexadecimal format.
fmt.Printf("hex: %x\n", 456)
// Printing a floating-point number.
fmt.Printf("float1: %f\n", 78.9)
// Printing a floating-point number in scientific notation.
fmt.Printf("float2: %e\n", 123400000.0)
fmt.Printf("float3: %E\n", 123400000.0)
// Printing a string.
fmt.Printf("str1: %s\n", "\"string\"")
// Printing a string with double quotes.
fmt.Printf("str2: %q\n", "\"string\"")
// Printing a string in hexadecimal format.
fmt.Printf("str3: %x\n", "hex this")
// Printing a pointer value.
fmt.Printf("pointer: %p\n", &p)
// Printing integers with specified width.
fmt.Printf("width1: |%6d|%6d|\n", 12, 345)
// Printing floating-point numbers with specified width and precision.
fmt.Printf("width2: |%6.2f|%6.2f|\n", 1.2, 3.45)
// Printing floating-point numbers with specified width and left alignment.
fmt.Printf("width3: |%-6.2f|%-6.2f|\n", 1.2, 3.45)
// Printing strings with specified width.
fmt.Printf("width4: |%6s|%6s|\n", "foo", "b")
// Printing strings with specified width and left alignment.
fmt.Printf("width5: |%-6s|%-6s|\n", "foo", "b")
// Using Sprintf to format a string.
s := fmt.Sprintf("sprintf: a %s", "string")
fmt.Println(s)
// Using Fprintf to format and print a string to os.Stderr.
fmt.Fprintf(os.Stderr, "io: an %s\n", "error")
}

output

struct1: {1 2}
struct2: {x:1 y:2}
struct3: main.point{x:1, y:2}
type: main.point
bool: true
int: 123
bin: 1110
char: !
hex: 1c8
float1: 78.900000
float2: 1.234000e+08
float3: 1.234000E+08
str1: "string"
str2: "\"string\""
str3: 6865782074686973
pointer: 0xc00000a0d0
width1: | 12| 345|
width2: | 1.20| 3.45|
width3: |1.20 |3.45 |
width4: | foo| b|
width5: |foo |b |
sprintf: a string
io: an error
Explanation:
  1. 1.
    Printing Structs:
    • struct1, struct2, and struct3 showcase different ways to print a struct (point in this case) with various formatting options.
  2. 2.
    Printing Types:
    • %T is used to print the type of a value.
  3. 3.
    Printing Booleans and Integers:
    • %t is used for boolean values.
    • %d is used for decimal integers.
  4. 4.
    Printing Binary, Character, and Hexadecimal:
    • %b prints integers in binary format.
    • %c prints a character using its ASCII value.
    • %x prints integers in hexadecimal format.
  5. 5.
    Printing Floating-Point Numbers:
    • %f prints floating-point numbers.
    • %e and %E print floating-point numbers in scientific notation.
  6. 6.
    Printing Strings:
    • %s prints strings.
    • %q prints strings with double quotes.
    • %x prints strings in hexadecimal format.
  7. 7.
    Printing Pointers:
    • %p is used to print pointer values.
  8. 8.
    Printing with Width and Alignment:
    • Various examples demonstrate printing with specified width and alignment using %6d, %6.2f, %-6.2f, %6s, and %-6s.
  9. 9.
    String Formatting with Sprintf:
    • Sprintf is used to format a string without printing it to the console.
  10. 10.
    Printing to os.Stderr:
    • Fprintf is used to format and print a string to os.Stderr.
This code provides a comprehensive overview of the formatting options available in the fmt package for various types of values.