Python re.fullmatch() Method

Python re 模块Python re Module

re.fullmatch()is a Pythonremodule used tofully matcha function for the entire string.

andre.match()Unlike,re.fullmatch()it requires the entire string to fully match the regular expression, not just match from the beginning.

Word Meaning： full matchmeans full match.

Basic Syntax and Parameters

re.fullmatch()is a module-level function, directly called viarethe module.

Syntax Format

re.fullmatch(pattern, string, flags=0)

Parameter Description

  • pattern：
    • Type: string (str)
    • Description: The regular expression pattern to match.
  • string：
    • Type: string (str)
    • Description: The string to be matched.
  • flags：
    • Type: integer (int, optional)
    • Description: Regular expression flags.

Function Description

  • Return value: If the entire string matches, returnsmatchobject; otherwise returnsNone。
  • Feature: Requires the string to match completely from beginning to end, no extra characters allowed.

Examples

Let's master through a series of examplesre.fullmatch()the usage of.

Example 1: Basic Usage - Full Match

Example

import re

# Fully match the entire string
text = "hello"

result = re.fullmatch(r'hello', text)

if result:
    print("Full match successful:", result.group())

Expected output:

完整匹配成功: hello

Code explanation:

  • re.fullmatch()Requires the string "hello" to fully match the pattern "hello".
  • The match succeeds, returning a match object.

Example 2: Case of Full Match Failure

If the string has extra characters, the match will fail.

Example

import re

text = "hello world"

# Try to fully match "hello"
result = re.fullmatch(r'hello', text)

if result:
    print("Match successful:", result.group())
else:
    print("Match failed: string is not exactly equal to 'hello'")

Expected output:

匹配失败: 字符串不是完全等于 'hello'

Code explanation:

  • The string "hello world" contains more characters, so it cannot fully match "hello".
  • In this case,fullmatchreturnsNone。

Example 3: Using Regular Expression Patterns

fullmatchSupports full regular expression syntax.

Example

import re

# Fully match digits
text = "12345"

result = re.fullmatch(r'\d+', text)

if result:
    print("Digit match:", result.group())

# Fully match letters
text2 = "abc"

result2 = re.fullmatch(r'[a-z]+', text2)

if result2:
    print("Letter match:", result2.group())

Expected output:

数字匹配: 12345
字母匹配: abc

Example 4: Validating Fixed Formats

fullmatchOften used to validate whether input conforms to a specific format.

Example

import re

# Validate phone number format
phone = "138-1234-5678"

result = re.fullmatch(r'\d{3}-\d{4}-\d{4}', phone)

if result:
    print(f"Phone number {phone} format is correct")
else:
    print(f"Phone number {phone} format is incorrect")

# Validate email format
email = "test@example.com"

result2 = re.fullmatch(r'\w+@\w+\.\w+', email)

if result2:
    print(f"Email {email} format is correct")
else:
    print(f"Email {email} format is incorrect")

Expected output:

手机号 138-1234-5678 格式正确
邮箱 test@example.com 格式正确

Code explanation:

  • fullmatchVery suitable for data validation scenarios.
  • Only when the string completely conforms to the format does the match succeed.

Example 5: Comparing match and fullmatch

Example

import re

text = "hello world"

# match only matches from the beginning
match_result = re.match(r'hello', text)

# fullmatch requires a full match
fullmatch_result = re.fullmatch(r'hello', text)

print("match result:", match_result.group() if match_result else None)
print("fullmatch result:", fullmatch_result.group() if fullmatch_result else None)

print("-" * 20)

# Try to fully match the entire string
text2 = "hello"

match_result2 = re.match(r'hello', text2)
fullmatch_result2 = re.fullmatch(r'hello', text2)

print("match result:", match_result2.group() if match_result2 else None)
print("fullmatch result:", fullmatch_result2.group() if fullmatch_result2 else None)

Expected output:

match 结果: hello
fullmatch 结果: None
--------------------
match 结果: hello
fullmatch 结果: hello

Code explanation:

  • re.match()It only needs to match from the beginning of the string; a full match is not required.
  • re.fullmatch()Requires the entire string to fully match from beginning to end.

Example 6: Using Groups

Example

import re

text = "2024-04-02"

# Use groups to fully match a date
result = re.fullmatch(r'(\d{4})-(\d{2})-(\d{2})', text)

if result:
    print("Full match:", result.group())
    print("Year:", result.group(1))
    print("Month:", result.group(2))
    print("Day:", result.group(3))

Expected output:

完整匹配: 2024-04-02
年: 2024
月: 04
日: 02

Python re 模块Python re Module

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