How to Split Text Using Regex in Golang?
Last Updated :
25 Aug, 2020
What is regex? Is Regex the famous anime character? Oops, if you think so, you're likely to be disappointed. The Go programming language uses the term regexp to denote Regular expressions. Regular expressions are very important in the field of string processing. The "regexp" package in Go holds all necessary pre-built functions that implement regular expression search and also guarantee a linear-time search in the size of the provided inputs. To know more about what regex is, read What is Regexp in Golang?
How to split input text using regexp (or regex)?
Regexp package contains the Split function which helps in splitting the input text string. Before we jump into the depths of regexp split function, let us brief you over some basic regular expressions that are worth remembering while using the split function:
Character(s) | What it signifies? | Example syntax | Result of regex |
---|
[ ]
| [ ] Can be used for including or excluding a given range, or even mention specifically the characters that we want to include or exclude. [ ] means both inclusive in a range.
| "[b-f]an"
| ban, can, dan, ean, fan
|
{ }
| The curly brackets are used when one needs to match the frequency of the occurrence of any given expression.
| "gf{1,}g"
| gfg, gffg, gfffg,...
|
( )
| ( ) Can be used for including or excluding a given range, or even mention specifically the characters that we want to include or exclude. ( ) means numbered capturing group. | "(b-f)an"
| ban, can, dan, ean, fan
|
*
| * Matches 0/0+ occurrences of the character that precedes the star ('*').
| "gee*k"
| gek, geek, geeek... |
+
| + Matches 1/1+ occurrences of the character that precedes the plus ('+').
| "gee+k"
| geek, geeek,...
|
?
| ? Matches 0 & 1 occurrences of the character that precedes the question mark ('?'). | "gee?k"
| gek, geek
|
.
| Anything can replace the dot character, except a newline (\n).
| "g.g"
| gfg, gbg, gcg,...
|
^
|
Any text that starts with the string mentioned after '^'.
Also used as a negation in groups or other regular expressions (NOT).
| "^ge"
"[^0-8]*"
| ge, geek, geeks,...
' ',9, 99,999,...
|
$
| It denotes the end of the string in a single-lined text and the end of a line in a multi-line text. | "$de"
| code, decode,...
|
|
| | is the or operator. | "geek|principle" | geek, geeks, principle, principles.. |
\
| This is the escape character If you need to mention anything like '\s' then you need to use ' \\s' so that the system understands that it is '\s'. | "\A" "\\n" "\\s" etc..
| |
\s
| Extracts all white spaces only | "\\s"
| " ", " ", " ",...
|
\S
| Extracts all text except white spaces | "\\S"
|
|
\d
| Extracts all digits only | "\\d"
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
|
\D
| Extracts all text except digits | "\\D"
| |
Syntax:
func Split(s: string, n: int) []string
This function accepts a string and an integer and returns a slice of all substrings. The input string 's' is the string that will be further, split into substrings as per the given regular expression by Split function. 'n' denotes the value that decides the number of substrings to be returned.
- If n > 0: It means that a maximum of n substrings undergo the regex operation and will be returned.
- If n = 1 then no regex the operation will be performed and hence, the original string will be returned.
- If n = 0: It means that no substrings will be returned, a nill shall be returned.
- If n < 0: It means that all the substrings that was created will be returned by the function.
Example 1:
Go
package main
import (
f "fmt"
re "regexp"
// we import the regexp package
// as re
)
// SPLIT function hacks
// In layman terms, whenever the
// string (given to split as argument)
// occurs, the string is split into
// a substring.
func main() {
// str stores a sample string as shown below
str := "I am at GFG!\nYou can call me at 9087651234."
// just printing the original string: str
f.Println(str)
// We shall consider two scenarios
// in this example code
// Scenario 1:
// Store a regex object that
// contains digits only
// in obj1.
obj1 := re.MustCompile("\\d*")
// Scenario 2:
// Store a regex object that
// contains everything except digits
// in obj2.
obj2 := re.MustCompile("\\D*")
// Using obj1 as reference, we
// are splitting the string: str
// and -1 denotes that all substrings
// ever created will be included.
first := obj1.Split(str, -1)
// "first" holds all the substrings
// split from str w.r.t obj1 in a container
// A container like, say a list.
// Using obj2 as reference, we
// are splitting the string: str
// and -1 denotes that all substrings
// ever created will be included.
second := obj2.Split(str, -1)
// "second" holds all the substrings
// split from str w.r.t obj2 in a container
// A container like, say a list.
f.Println("Now printing text split by obj1...")
for _, p := range first {
f.Println(p)
}
f.Println("Now printing text split by obj2...")
for _, q := range second {
f.Println(q)
}
}
Command to Execute:
> go run (your_file_name).go
Output:
I am at GFG!
You can call me at 9087651234.
Now printing text split by obj1...
I
a
m
a
t
G
F
G
!
Y
o
u
c
a
n
c
a
l
l
m
e
a
t
.
Now printing text split by obj2...
9
0
8
7
6
5
1
2
3
4
Visual I/O demo on Visual Studio Code:
Code output on-screen upon running the above-written code.
Example 2:
Go
package main
import (
f "fmt"
re "regexp"
)
// Simple example code to understand
// 1. Function of Split function
// 2. Parameters of split function
// regex-object.Split(string: , n: )
func main() {
// Sample string that will be used in this
// example "GeeksforGeeks loves bananas"
str := "GeeksforGeeks loves bananas"
f.Println(str)
f.Println("Part-1: Excluding all vowels from given string")
// a regexp object (geek) for storing all vowels
geek := re.MustCompile("[aeiou]")
f.Print("Printing all substring lists = ")
// Checking split for n = -1
f.Println(geek.Split(str, -1))
f.Print("For n = 0 substring list = ")
// Checking split for n = 0
f.Println(geek.Split(str, 0))
f.Print("For n = 1 substring list = ")
// Checking split for n = 1
f.Println(geek.Split(str, 1))
f.Print("For n = 10 substring list = ")
// Checking split for n = 10
f.Println(geek.Split(str, 10))
f.Print("For n = 100 substring list = ")
// Checking split for n = 100
f.Println(geek.Split(str, 100))
f.Println("\n\nPart-2: Extracting all vowels from given string")
// a regexp object (geek) for storing all consonants
geek = re.MustCompile("[^aeiou]")
f.Print("Printing all substring lists = ")
// Checking split for n = -1
f.Println(geek.Split(str, -1))
f.Print("For n = 0 substring list = ")
// Checking split for n = 0
f.Println(geek.Split(str, 0))
f.Print("For n = 1 substring list = ")
// Checking split for n = 1
f.Println(geek.Split(str, 1))
f.Print("For n = 10 substring list = ")
// Checking split for n = 10
f.Println(geek.Split(str, 10))
f.Print("For n = 100 substring list = ")
// Checking split for n = 100
f.Println(geek.Split(str, 100))
// Did you notice that split function
// does not modify the original regex
// matching object?
}
Command to Execute:
> go run (your_file_name).go
Output:
GeeksforGeeks loves bananas
Part-1: Excluding all vowels from given string
Printing all substring lists = [G ksf rG ks l v s b n n s]
For n = 0 substring list = []
For n = 1 substring list = [GeeksforGeeks loves bananas]
For n = 10 substring list = [G ksf rG ks l v s b n nas]
For n = 100 substring list = [G ksf rG ks l v s b n n s]
Part-2: Extracting all vowels from given string
Printing all substring lists = [ ee o ee o e a a a ]
For n = 0 substring list = []
For n = 1 substring list = [GeeksforGeeks loves bananas]
For n = 10 substring list = [ ee o ee loves bananas]
For n = 100 substring list = [ ee o ee o e a a a ]
Visual I/O demo on Visual Studio Code:
Code output on-screen upon running the above-written code.
Similar Reads
How to Split a String in Golang? In Go language, strings differ from other languages like Java, C++, and Python. A string in Go is a sequence of variable-width characters, with each character represented by one or more bytes using UTF-8 encoding. In Go, you can split a string into a slice using several functions provided in the str
3 min read
Matching using regexp in GoLang Regexp is the short form of Regular expressions. People generally confuse regexp with regex, and that's obvious because other programming languages such as Python use the term regex for their regular expression library, but Go uses regexp and it's important to remember it as regexp as it is the name
11 min read
How to Sort a Slice of Strings in Golang? In Go, a slice is a flexible data structure that stores a variable-length sequence of elements of the same type. Unlike arrays, slices can dynamically grow and shrink. You cannot mix different types within a slice. Go provides built-in functions for sorting slices, particularly for strings, found in
2 min read
How to split a slice of bytes in Golang? In Golang, you can split a slice of bytes into multiple parts using the bytes.Split function. This is useful when dealing with data like encoded strings, file contents, or byte streams that must be divided by a specific delimiter.Examplepackage mainimport ( "bytes" "fmt")func main() { // Initial byt
3 min read
How to trim a slice of bytes in Golang? In Go language slice is more powerful, flexible, convenient than an array, and is a lightweight data structure. The slice is a variable-length sequence which stores elements of a similar type, you are not allowed to store different type of elements in the same slice. In the Go slice of bytes, you ar
3 min read
How to Trim a String in Golang? In Go, strings are UTF-8 encoded sequences of variable-width characters, unlike some other languages like Java, python and C++. Go provides several functions within the strings package to trim characters from strings.In this article we will learn how to Trim a String in Golang.Examples := "@@Hello,
2 min read
How to print string with double quotes in Golang? Whenever the user wants to double-quote a string, he can't simply write the string within double quotes inside the fmt.Printf() command. This prints only the text written inside those quotes. To print the string along with quotes, he can use various methods including certain escape characters. There
2 min read
How to append a slice in Golang? In Go, slices are dynamically-sized, flexible views into the elements of an array. Appending elements to a slice is a common operation that allows for the expansion of the slice as needed. The built-in append function is used to add elements to the end of a slice.In this article,we will learn How to
2 min read
How to Convert string to integer type in Golang? Strings in Golang is a sequence of variable-width characters where each and every character is represented by one or more bytes using UTF-8 Encoding. In Go language, both signed and unsigned integers are available in four different sizes. In order to convert string to integer type in Golang, you can
2 min read
How to use strconv.Quote() Function in Golang? Go language provides inbuilt support to implement conversions to and from string representations of basic data types by strconv Package. This package provides a Quote() function which is used to find a double-quoted Go string literal representing str and the returned string uses Go escape sequences
2 min read