What are the formatting placeholders in golang?

go formatted placeholders can be divided into: 1. Ordinary placeholders, including "%v", "% v", "%#v", "%T", etc.; 2. Boolean placeholders placeholder "%t"; 3. Integer placeholders, including "%b", "%c", "%d", "%o", etc.; 4. Floating point and complex number placeholders, including "%b" ", "%e", "%E", "%f", etc.; 5. String and byte slice placeholders, including "%s", "%q", "%x", etc.; 6. Pointers Placeholder "%p"; 7. Other marks, including " ", "-", and "#".

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

In Golang, formatted input and output require the use of formatted placeholders. For example, the function fmt.Scanf() that obtains data input by the user, and the function fmt.Printf() that formats the output.

The formatting placeholders of Go language can be roughly divided into ordinary placeholders, Boolean placeholders, integer placeholders, floating point and complex number placeholders, string and byte slice placeholders. , pointers, placeholders and other markers, etc.

Normal placeholder

##% vWhen printing the structure, the field name will be addedPrintf("% v ”, webSite){Name:HaiCoder}%#vGo syntax representation of the corresponding valuePrintf( "#v", webSite)main.WebSite{Name:"HaiCoder"}%TGo syntax for the type of the corresponding value Represents Printf("%T", webSite)main.WebSite%% Literal percentage number, not a placeholder for a valuePrintf("%%")%

Placeholder	Explanation	Example	Output
%v	Default format of the corresponding value	Printf("%v", webSite )	{HaiCoder}

Boolean placeholder

PlaceholderDescriptionExampleOutput%ttrue or falsePrintf("%t", true)true

Integer placeholder

PlaceholderExplanationExample Output%bBinary representationPrintf("%b", 5)101%cThe character represented by the corresponding Unicode code pointPrintf("%c", 0x4E2D)中%dDecimal representationPrintf("%d", 0x12)18%oOctal representationPrintf("%d", 10)12%q Single quoted character literal, safely escaped by Go syntax Printf("%q", 0x4E2D)' '%xHexadecimal representation, the letter form is lowercase a-fPrintf("%x", 13)d##%X%U

Hexadecimal representation, the letter form is uppercase A-F	Printf("%x", 13)	D
Unicode format: U 1234, equivalent to "U X"	Printf("%U", 0x4E2D )	U 4E2D

Components of floating point numbers and complex numbers (real and imaginary parts)

Placeholder%b##%e Scientific notation, for example -1234.456e 78Printf("%e", 10.2)1.020000e 01%EScientific notation, for example - 1234.456E 78Printf("%e", 10.2)1.020000E 01With decimal point but without Index, for example 123.456##%gSelect %e according to the situation or %f to produce more compact (no trailing 0s) OutputPrintf("%g", 10.20)10.2% GChoose %E or %f as appropriate to produce a more compact (no trailing 0)OutputPrintf("%G", 10.20 2i)(10.2 2i)

String and byte slices

Description	Example	Output
Scientific notation with no decimal part and an exponent of a power of two, consistent with the 'b' conversion format of strconv.FormatFloat. For example -123456p-78
			##%f
Printf("%f", 10.2)	10.200000

##%sOutput string representation (string type or []byte)Printf( "%s", []byte("Go language"))Go language%qA string surrounded by double quotes, Safely escaped by Go syntaxPrintf("%q", "Go language")"Go language"%xHexadecimal, lowercase letters, two characters per bytePrintf("%x", "golang")686a6c61164a%XHexadecimal, uppercase letters, two characters per bytePrintf("%X", "golang")686F6A616C61

Placeholder	Description	Example	Output

Pointer

PlaceholderDescriptionExampleOutput##%p##Other tags

Hexadecimal representation, prefix 0x	Printf("%p", &people)	0x4a56a0

PlaceholderDescriptionExampleOutputAlways print the positive and negative sign of the value; for %q (% q), only ASCII-encoded characters are guaranteed to be output. Printf("% q", "中文") "\u4e2d\u6587"Padding spaces on the right side instead of the left (left align the area) # Alternate formats: add leading 0 (%#o) for octal, add leading 0x (%#x) or 0X (%#X) for hexadecimal, remove leading 0x for %p (%#p); if If possible, %q (%#q) will print the original (i.e., surrounded by backtick marks) string; if it is a printable character, %U (%#U) will write out the Unicode encoding of the character (for example, the character x will Printed as U 0078 'x') ##Space) Leave space for omitted signs in numeric values ​​(% d) When printing a string or slice in hexadecimal (% x, % Separate the spaces with Padding leading 0s instead of spaces; for numbers, this shifts the padding After reaching the plus and minus signs 、programming teaching】

			##-
Printf("%#U", '中')	U 4E2D		' '
			0
			#[Related recommendations: Go video tutorial

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