Examples of several methods for Python regular expressions

Preface

Calling method:

(pattern, string, flags=0)

Usage description:Scan the entire string to find all characters that satisfy the matching style, and collect them together and return them in a list form. The returned list contains empty results (no matching results).

Example 1

import re

str1 = "The telephone number of police in China is 110, and the telephone number of emergency is 120."
pattern = "\d+"
result = (pattern, str1)
print(result)
"""
result:
['110', '120']
"""

Can be seen. Through this matching method, we successfully find all the numeric objects in a string and collect them together as a list object and return them.

Example 2

import re

str1 = "I got 1.0， and my classmate got 2.0."
pattern = "\d+"
result = (pattern, str1)
print(result)
"""
result:
['1', '0', '2', '0']
"""

We want to get it through matching1.0and2.0These two numbers. However, things went against our expectations. We got four independent numbers. What should we do? The following code should be used:

import re

str1 = "I got 1.0， and my classmate got 2.0."
pattern = "\d.\d"
result = (pattern, str1)
print(result)
"""
result:
['1.0', '2.0']
"""

As you can see, we have successfully obtained the numbers we need.

Example Three

import re

str1 = "I got 1.0， and my classmate got 2.0."
pattern = "\d\d"
result = (pattern, str1)
print(result)
"""
result:
[]
"""

When we cannot find a matching object, an empty list object will be returned. This is with()The usage description of the function is consistent.

Summarize

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