1. Universal formatted output For formatted output in Go language, the fmt package is usually used. The common output format is as shown in the following table:
Output format Output content
%v
The default format representation of the value
%+v
Similar to %v, but field names will be added when outputting the structure
%#v
Go syntax representation of value
%T Go syntax representation of value types
package main
import "fmt"
func main() {
var s string = "ajwlf"
var z int = 1
var r rune = '一'
fmt.Printf("s: %v\n", s)
fmt.Printf("s: %+v\n", s)
fmt.Printf("s: %#v\n", s)
fmt.Printf("s: %T\n", s)
fmt.Printf("z: %v\n", z)
fmt.Printf("z: %T\n", z)
fmt.Printf("r: %v\n", r)
fmt.Printf("r: %T\n", r)
}
out:
s: ajwlf
s: ajwlf
s: "ajwlf"
s: string
z: 1
z: int
r: 19968
r: int32
2.Boolean type
Output format Output content
%t
word true or false
package main
import "fmt"
func main() {
var flag bool
fmt.Printf("%T, %t \n", flag, flag)
flag = true
fmt.Printf("%T, %t \n", flag, flag)
}
// 结果
bool, false
bool, true
3. Integer type
Output format Output content
%b
Represented as binary
%c
The unicode code value corresponding to this value
%d
Expressed as decimal
%8d It means that the length of the integer is 8. If it is less than 8, add a space before the value; if it exceeds 8, the actual value shall prevail.
%08d It means that the length of the integer is 8. If it is less than 8, add 0 in front of the value; if it exceeds 8, the actual value shall prevail.
%o
Represented as octal
%q
The Go language syntax character literal value corresponding to this value is enclosed in single quotes and will be represented by a safe escape when necessary.
%x
Expressed in hexadecimal, use a~f
%X
Expressed in hexadecimal, use A~F
%U
Represented as unicode format: U+1234, equivalent to U+%04X
%p
pointer type
package main
import "fmt"
func main() {
fmt.Printf("%T, %d \n", 123, 123)
fmt.Printf("%T, %5d \n", 123, 123)
fmt.Printf("%T, %05d \n", 123, 123)
fmt.Printf("%T, %b \n", 123, 123)
fmt.Printf("%T, %o \n", 123, 123)
fmt.Printf("%T, %c \n", 97, 97)
fmt.Printf("%T, %q \n", 97, 97)
fmt.Printf("%T, %x \n", 123, 123)
fmt.Printf("%T, %X \n", 123, 123)
fmt.Printf("%T, %U \n", '一', '一')
}
// 结果
int, 123
int, 123
int, 00123
int, 1111011
int, 173
int, a
int, 'a'
int, 7b
int, 7B
int32, U+4E00
4. Floating point type and complex number type
Output format Output content
%b Scientific notation without decimal part and binary exponent, such as -123456p-78
%e
(=%.6e) Scientific notation with 6 decimal places, such as -1234.456e+78
%E
Scientific notation, such as -1234.456E+78
%f
(=%.6f) has 6 decimal places, such as 123.456123
%F
Equivalent to %f
%g
Use %e or %f format according to actual situation (obtain more concise and accurate output)
%G
Use %E or %F format according to actual situation (obtain more concise and accurate output)
package main
import "fmt"
func main() {
fmt.Printf("%b \n", 123.123456)
fmt.Printf("%f \n", 123.1)
fmt.Printf("%.2f \n", 123.125456)
fmt.Printf("%e \n", 123.123456)
fmt.Printf("%E \n", 123.123456)
fmt.Printf("%.1e \n", 123.123456)
fmt.Printf("%F \n", 123.123456)
fmt.Printf("%g \n", 123.123456)
fmt.Printf("%G \n", 123.123456)
}
// 结果
8664042977533870p-46
123.100000
123.13
1.231235e+02
1.231235E+02
1.2e+02
123.123456
123.123456
123.123456
5. Strings and byte arrays
Output format Output content
%s
Directly output string or byte array
%q The Go syntax string literal value corresponding to this value is enclosed in double quotes and will be safely escaped if necessary.
%x Each byte is represented by a two-character hexadecimal number, using a~f
%X Each byte is represented by a two-character hexadecimal number, using A~F
package main
import "fmt"
func main() {
arr := []byte{'x', 'y', 'z', 'z'}
fmt.Printf("%s \n", "欢迎访问")
fmt.Printf("%q \n", "欢迎访问")
fmt.Printf("%x \n", "欢迎访问")
fmt.Printf("%X \n", "欢迎访问")
fmt.Printf("%T, %s \n", arr, arr)
fmt.Printf("%T, %q \n", arr, arr)
fmt.Printf("%T, %x \n", arr, arr)
fmt.Printf("%T, %X \n", arr, arr)
}
//
欢迎访问
"欢迎访问"
e6aca2e8bf8ee8aebfe997aee5beaee5ada6e88b91
E6ACA2E8BF8EE8AEBFE997AEE5BEAEE5ADA6E88B91
[]uint8, xyzz
[]uint8, "xyzz"
[]uint8, 78797a7a
[]uint8, 78797A7A