Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
g

Test String

Code Generator

Language

Generated Code

package main import ( "regexp" "fmt" ) func main() { var re = regexp.MustCompile(`(?(DEFINE)(?'NAMESPACE'\w*::))(?#r)(?(DEFINE)(?'CONSTANT'("(?:[^"\\]|\\.)*")|(\d+\.?\d*f?)))(?#r)(?(DEFINE)(?'VARIABLE'(?P>NAMESPACE)*([A-Za-z_]\w*\.)*[A-Za-z_]\w*))(?#r)(?(DEFINE)(?'OPERAND'(\+|-)*((?P>VARIABLE)|(?P>CONSTANT))))(?#r)(?(DEFINE)(?'EXPRESSION'\s*(?P>OPERAND)\s*(\s*[\*\+-\/]\s*(?P>OPERAND))*))(?#r)(?(DEFINE)(?'ARGUMENTS'(?P>EXPRESSION)(,\s*(?P>EXPRESSION))*))(?#r)(?(DEFINE)(?'FUNCTION_CALL'(?P>VARIABLE)\(\s*(?P>ARGUMENTS)?\s*\)))(?#r)(?P>FUNCTION_CALL)`) var str = ` [[ ::anno::copyright_notice("XXXXX"), ::anno::author("Someone"), ::anno::contributor("") ]] = let { bool tmp0 = false; material_surface tmp1( Use_Clearcoat ? ::df::custom_curve_layer(Clearcoat_Center_Level * 0.08f, Clearcoat_Edge_Level, 5.f, 1.f, ::df::microfacet_ggx_smith_bsdf(::math::luminance(::nvidia::core_definitions::blend_colors(color(0.f, 0.f, 0.f), ::base::file_texture(Coat_Roughness_Map, color(0.f, 0.f, 0.f), color(1.f, 1.f, 1.f), ::base::mono_luminance, ::base::texture_coordinate_info(::state::texture_coordinate(0), ::state::texture_tangent_u(0), ::state::texture_tangent_v(0)), float2(0.f, 1.f), float2(0.f, 1.f), ::tex::wrap_repeat, ::tex::wrap_repeat, false).tint, ::base::color_layer_blend, Coat_Roughness_Map_Strength).tint) * ::math::luminance(::nvidia::core_definitions::blend_colors(color(0.f, 0.f, 0.f), ::base::file_texture(Coat_Roughness_Map, color(0.f, 0.f, 0.f), color(1.f, 1.f, 1.f), ` for i, match := range re.FindAllString(str, -1) { fmt.Println(match, "found at index", i) } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/