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GoLang fmt Printing Cheat Sheet by

Go fmt package verbs to be used with fmt.Printf()

String and slice of bytes

%s
the uninte­rpreted bytes of the string or slice
%q
a double­-quoted string safely escaped with Go syntax
%x
base 16, lower-­case, two characters per byte
%X
base 16, upper-­case, two characters per byte

General

%v
The value in a default format. When printing structs, the plus flag (%+v) adds field names.
%#v
a Go-syntax repres­ent­ation of the value
%T
a Go-syntax repres­ent­ation of the type of the value
%%
a literal percent sign; consumes no value

The default format for %v

bool:
%t
int, int8 etc.:
%d
uint, uint8 etc.:
%d, %x if printed with %#v
float32, complex64, etc:
%g
string:
%s
chan:
%p
pointer:
%p

Other flags

+
always print a sign for numeric values; guarantee ASCII-only output for %q (%+q).
-
pad with spaces on the right rather than the left (left-­justify the field).
#
alternate format: add leading 0 for octal (%#o), 0x for hex (%#x); 0X for hex (%#X); suppress 0x for %p (%#p); for %q, print a raw (backq­uoted) string if strcon­v.C­anB­ack­quote returns true;
' ' (space)
leave a space for elided sign in numbers (% d); put spaces between bytes printing strings or slices in hex (% x, % X).
0
pad with leading zeros rather than spaces; for numbers, this moves the padding after the sign.
 

Boolean

%t
the word true or false

Integer

%b
base 2
%c
the character repres­ented by the corres­ponding Unicode code point
%d
base 10
%o
base 8
%q
a single­-quoted character literal safely escaped with Go syntax
%x
base 16, with lower-case letters for a-f
%X
base 16, with upper-case letters for A-F
%U
Unicode format: U+1234; same as "­U+%­04X­"

Floati­ng-­point and complex consti­tuents

%b
decima­lless scientific notation with exponent a power of two, in the manner of strcon­v.F­orm­atFloat with the 'b' format, e.g. -12345­6p-78
%e
scientific notation, e.g. -1.234­456e+78
%E
scientific notation, e.g. -1.234­456E+78
%f
decimal point but no exponent, e.g. 123.456
%F
synonym for %f
%g
%e for large exponents, %f otherwise
%G
%E for large exponents, %F otherwise

Floati­ng-­point Precision

%f
default width, default precision
%9f
width 9, default precision
%.2f
default width, precision 2
%9.2f
width 9, precision 2
%9.f
width 9, precision 0

Pointer

%p
base 16 notation, with leading 0x
   
 

Metadata

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  • Published: 17th November, 2016
  • Rated: 5 stars based on 2 ratings

Favourited By

indeveler TheCodeGetter trumpi

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