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

/
/
gms

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "(?P<file_number>\\d+)\\.\\s+(?P<filepath>.*?)\\n(?P<file_contents>```(.*?)```)(?=\\d+\\.\\s+|$)"; final String string = "1. nextflow.config\n" + "```\n" + "params {\n" + " inputDir = \"data/raw\"\n" + " outputDir = \"results\"\n" + "}\n\n" + "process {\n" + " executor = \"local\"\n" + " memory = \"8 GB\"\n" + " cpus = 4\n" + "}\n" + "```\n\n" + "2. main.nf\n" + "```\n" + "#!/usr/bin/env nextflow\n\n" + "params.inputDir = \"./data/raw\"\n" + "params.outputDir = \"./results\"\n\n" + "include { preprocess, qualityControl, differentialExpression } from \"./scripts\"\n\n" + "workflow {\n" + " input:\n" + " path(inputDir) from params.inputDir\n\n" + " output:\n" + " path(outputDir) into results\n\n" + " preprocess_output, quality_control_output, differential_expression_output = script {\n" + " preprocess(inputDir)\n" + " } \n\n" + " quality_control_output = script {\n" + " qualityControl(preprocess_output)\n" + " }\n\n" + " differential_expression_output = script {\n" + " differentialExpression(preprocess_output)\n" + " }\n" + "}\n" + "```\n\n" + "3. scripts/preprocess.sh\n" + "```\n" + "#!/bin/bash\n\n" + "inputDir=$1\n\n" + "# Trim reads using Trimmomatic\n" + "trimmomatic PE ${inputDir}/sample_R1.fastq.gz ${inputDir}/sample_R2.fastq.gz ${inputDir}/sample_R1.trimmed.fastq.gz ${inputDir}/sample_R1.unpaired.fastq.gz ${inputDir}/sample_R2.trimmed.fastq.gz ${inputDir}/sample_R2.unpaired.fastq.gz ILLUMINACLIP:adapters.fa:2:30:10 LEADING:3 TRAILING:3 SLIDINGWINDOW:4:15 MINLEN:36\n\n" + "# Align trimmed reads using HISAT2\n" + "hisat2 -x genome_index -1 ${inputDir}/sample_R1.trimmed.fastq.gz -2 ${inputDir}/sample_R2.trimmed.fastq.gz -S ${inputDir}/sample.sam\n\n" + "# Convert SAM to BAM\n" + "samtools view -bS ${inputDir}/sample.sam > ${inputDir}/sample.bam\n\n" + "# Sort BAM file\n" + "samtools sort ${inputDir}/sample.bam -o ${inputDir}/sample.sorted.bam\n\n" + "# Index sorted BAM file\n" + "samtools index ${inputDir}/sample.sorted.bam\n\n" + "# Remove intermediate files\n" + "rm ${inputDir}/sample.sam ${inputDir}/sample.bam\n" + "```\n\n" + "4. scripts/quality_control.sh\n" + "```\n" + "#!/bin/bash\n\n" + "inputDir=$1\n\n" + "# Run FastQC on trimmed reads\n" + "fastqc ${inputDir}/sample_R1.trimmed.fastq.gz ${inputDir}/sample_R2.trimmed.fastq.gz -o ${inputDir}\n\n" + "# Move FastQC output to results directory\n" + "mv ${inputDir}/*.html ${inputDir}/*.zip ${inputDir}/../results/logs\n" + "```\n\n" + "5. scripts/differential_expression.sh\n" + "```\n" + "#!/bin/bash\n\n" + "inputDir=$1\n\n" + "# Count reads using featureCounts\n" + "featureCounts -T 4 -a annotation.gtf -o ${inputDir}/counts.txt ${inputDir}/sample.sorted.bam\n\n" + "# Perform differential expression analysis using DESeq2\n" + "Rscript differential_expression.R ${inputDir}/counts.txt ${inputDir}/../results/differential_expression_results.txt\n" + "```\n\n" + "Note: The contents of the `data/` and `results/` directories are not provided as they would depend on the specific input data and expected output structure.\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE | Pattern.DOTALL); final Matcher matcher = pattern.matcher(string); while (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(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 Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html