[Python] A game that uses regular expressions when, where, who, and what

Purpose

・ I learned regular expressions, so I'll enjoy using them for the time being.

environment

• Visual Studio Code
• Python

procedure

I wrote them all in one file (practice.py).

(1) Import the re module, which is a standard library for regular expressions

practice.py

import re

② Prepare a question

practice.py

question = "When? where? who? What did you do?"

③ Define the function four_ws_game

practice.py

def four_ws_game(sentence):
    words = re.findall(".*?？", sentence)
    i = 0
    while i < len(words):
        answer = input(f"{words[i]}:").strip()
        if answer == "":
            print("Please do it seriously")
        else:
            sentence = sentence.replace(words[i], answer)
            i += 1
    print(sentence)

It's hard to understand, so let's disassemble it.

3-1. Use the findall function of the re module

--The findall function lists the ** matched parts ** in the sentence and passes it to the variable words. --. (Period) ** in regular expressions means any single character - \ * (asterisk) ** means repeat

practice.py

words = re.findall(".*?？", sentence)

In other words, this program is at the end of the sentence (sentense) **? Words with any number of characters with (double-byte question) ** Find and list.

-**? (Half-width question) ** is necessary to extract the above words one by one. -Let's see how the contents of the list change depending on the presence or absence of? (Half-width question)

Yes

practice.py

words = re.findall(".*?？", sentence)
print(words)

Execution result

['When?', 'where?', 'who?', 'What did you do?']

Nothing

practice.py

words = re.findall(".*？", sentence)
print(words)

Execution result

['When? where? who? What did you do?']

3-2. Rewrite the contents of the sentence (sentence) to the input value and print

practice.py

i = 0
while i < len(words):
    answer = input(f"{words[i]}:").strip()
    if answer == "":
        print("Please do it seriously")
    else:
        sentence = sentence.replace(words[i], answer)
        i += 1
print(sentence)

④ Set sentence as the first prepared question and execute it.

practice.py

four_ws_game(question)

Whole code

practice.py

import re

question = "When? where? who? What did you do?"

def four_ws_game(sentence):
    words = re.findall(".*?？", sentence)
    i = 0
    while i < len(words):
        answer = input(f"{words[i]}:").strip()
        if answer == "":
            print("Please do it seriously")
        else:
            sentence = sentence.replace(words[i], answer)
            i += 1
    print("What happened? :" + sentence)

four_ws_game(question)

• Execution result

When?:Yesterday
where?:At home
who?:Cat
What did you do?:I fell asleep
What happened? : The cat fell at home yesterday

--I get angry when I try to leave it blank

When?:Yesterday
where?:
Please do it seriously
where?:At home
who?:Cat
What did you do?:
Please do it seriously
What did you do?:Became a dog
What happened? : The cat became a dog at home yesterday