2.5. Go fmt.Sprintf format string

Go can be used fmt.Sprintf to format the string in the following format:

fmt.Sprintf(Format style, parameter list…)

Format style: in the form of a string, formatting symbols to % at the beginning %s string format, %d decimal integer format.
Parameter list: multiple parameters are separated by commas, and the number must correspond to the number in the formatting style one by one, otherwise the runtime will report an error.

2.5.1. Example #

package main
import (
    "fmt"
    "io"
    "os"
)
func main() {
    // Format the string in go and assign it to a new string, using fmt.Sprintf
    // %S represents a string
    var stockcode="000987"
    var enddate="2020-12-31"
    var url="Code=%s&endDate=%s"
    var target_url=fmt.Sprintf(url,stockcode,enddate)
    fmt.Println(target_url)
    // Another instance,% d represents an integer
    const name, age = "Kim", 22
    s := fmt.Sprintf("%s is %d years old.\\n", name, age)
    io.WriteString(os.Stdout, s) // For simplicity, ignore some errors
}

The output is as follows:

Code=000987&endDate=2020-12-31
Kim is 22 years old.

Go string formatting symbol:

Format	Description
%v	Output by the original value of the value
%+v	Expand the structure field name and value on the basis of%v
%#v	Output values in Go language syntax format
%T	Output the types and values of the Go language syntax format
%%	Output% ontology
%b	The integer is displayed in binary mode
%o	Integers are displayed in octal mode
%d	Integers are displayed in decimal mode
%x	The integer is displayed in hexadecimal mode
%X	Integers are displayed in hexadecimal, uppercase letters
%U	Unicode character
%f	Floating point number
%p	Pointer, displayed in hexadecimal mode

2.5.2. Example #

package main
import (
    "fmt"
    "os"
)
type point struct {
    x, y int
}
func main() {
    p := point{1, 2}
    fmt.Printf("%v\\n", p)
    fmt.Printf("%+v\\n", p)
    fmt.Printf("%#v\\n", p)
    fmt.Printf("%T\\n", p)
    fmt.Printf("%t\\n", true)
    fmt.Printf("%d\\n", 123)
    fmt.Printf("%b\\n", 14)
    fmt.Printf("%c\\n", 33)
    fmt.Printf("%x\\n", 456)
    fmt.Printf("%f\\n", 78.9)
    fmt.Printf("%e\\n", 123400000.0)
    fmt.Printf("%E\\n", 123400000.0)
    fmt.Printf("%s\\n", "\\"string\\"")
    fmt.Printf("%q\\n", "\\"string\\"")
    fmt.Printf("%x\\n", "hex this")
    fmt.Printf("%p\\n", &p)
    fmt.Printf("|%6d|%6d\|\\n", 12, 345)
    fmt.Printf("|%6.2f|%6.2f\|\\n", 1.2, 3.45)
    fmt.Printf("|%-6.2f|%-6.2f\|\\n", 1.2, 3.45)
    fmt.Printf("|%6s|%6s\|\\n", "foo", "b")
    fmt.Printf("|%-6s|%-6s\|\\n", "foo", "b")
    s := fmt.Sprintf("a %s", "string")
    fmt.Println(s)
    fmt.Fprintf(os.Stderr, "an %s\\n", "error")
}

The output is as follows:

{1 2}
{x:1 y:2}
main.point{x:1, y:2}
main.point
true
123
1110
!
1c8
78.900000
1.234000e+08
1.234000E+08
"string"
"\"string\""
6865782074686973
0xc0000b4010
|    12|   345|
|  1.20|  3.45|
|1.20  |3.45  |
|   foo|     b|
|foo   |b     |
a string
an error