golang格式化输出函数printf、sprintf、fprintf解读

// Printf formats according to a format specifier and writes to standard output.
// It returns the number of bytes written and any write error encountered.
func Printf(format string, a ...any) (n int, err error) {
	return Fprintf(os.Stdout, format, a...)
}

func main() {
	name := "haha"
	age := 18
	fmt.Printf("%s今年%d岁了\n", name, age) //haha今年18岁了
}

	fmt.Println("----------------------------------")
	a, o := fmt.Printf("哈")
	fmt.Println() //打印空行 好观察
	fmt.Println(a, o)

	a1, o1 := fmt.Printf("哈\n")
	fmt.Println(a1, o1)

	a11, o11 := fmt.Printf("哈\n\n")
	fmt.Println(a11, o11)

	a2, o2 := fmt.Printf("abc")
	fmt.Println()
	fmt.Println(a2, o2)

	a3, o3 := fmt.Printf("%s", "abc")
	fmt.Println()
	fmt.Println(a3, o3)

// Sprintf formats according to a format specifier and returns the resulting string.
func Sprintf(format string, a ...any) string {
	p := newPrinter()
	p.doPrintf(format, a)
	s := string(p.buf)
	p.free()
	return s
}

	name := "aabb"
	age := 18

	s := fmt.Sprintf("%s今年%d岁了", name, age)
	fmt.Println(s)    //aabb今年18岁了

// Fprintf formats according to a format specifier and writes to w.
// It returns the number of bytes written and any write error encountered.
func Fprintf(w io.Writer, format string, a ...any) (n int, err error) {
	p := newPrinter()
	p.doPrintf(format, a)
	n, err = w.Write(p.buf)
	p.free()
	return
}

	type Writer interface {
		Write(p []byte) (n int, err error)
	}