Go语言中的格式化输出占位符的用法详解

package main

import (
    "fmt"
)

func main() {
    // 字符串格式化
    fmt.Printf("String: %s\n", "Hello")
    fmt.Printf("Quoted String: %q\n", "Hello")

    // 数字格式化
    fmt.Printf("Decimal: %d\n", 123)
    fmt.Printf("Binary: %b\n", 123)
    fmt.Printf("Octal: %o\n", 123)
    fmt.Printf("Hexadecimal (lower): %x\n", 123)
    fmt.Printf("Hexadecimal (upper): %X\n", 123)
    fmt.Printf("Character: %c\n", 65)
    fmt.Printf("Unicode: %U\n", 'A')

    // 浮点数格式化
    fmt.Printf("Float: %f\n", 123.456)
    fmt.Printf("Scientific (lower): %e\n", 123.456)
    fmt.Printf("Scientific (upper): %E\n", 123.456)
    fmt.Printf("General (lower): %g\n", 123.456)
    fmt.Printf("General (upper): %G\n", 123.456)

    // 布尔值格式化
    fmt.Printf("Boolean: %t\n", true)

    // 指针地址格式化
    var value int = 123
    fmt.Printf("Pointer: %p\n", &value)

    // 类型名称格式化
    fmt.Printf("Type: %T\n", value)

    // 特殊格式化
    fmt.Printf("Default Format: %v\n", "Hello")
    fmt.Printf("Struct Fields: %+v\n", struct{ Name string }{"Alice"})
    fmt.Printf("Go Syntax: %#v\n", "Hello")

    // 自定义宽度和精度
    fmt.Printf("Width: %5d\n", 123)
    fmt.Printf("Zero-Padded Width: %05d\n", 123)
    fmt.Printf("Precision: %.2f\n", 123.456)

    // 对齐方式
    fmt.Printf("Left-Aligned: %-5d\n", 123)
    fmt.Printf("Right-Aligned: %+5d\n", 123)
}

package main

import (
    "log"
)

func main() {
    log.Printf("Log Message: %s", "Hello")
}