📌 文字列データ型

👉 文字列=引用符で囲む

"python"
"123"

👉 4つの文字列の作成方法

"python"
'python'
"""python"""
'''python'''

👉 引用符を文字列に含める!

cv変数にIt's my Developgを保存

>>> cv = "It's my velog"

say変数では「It's myvelog」と述べた。保存＃ホゾン＃

>>> say = '"It is my velog", he says.'

スラッシュの使用()

>>> cv = 'It\'s my velog'
>>> say = "\"It is my velog\", he says."

👉 複数行文字列を変数に挿入

Multiline変数で..。保存＃ホゾン＃

I love music.
My best thing is dusk till dawn.

nエスケープコードを挿入n

>>> multiple = "I love music.\nMy best thing is dusk till dawn."

連続3つの引用符

>>> multiline = """
I love music.
My best thing is dusk till dawn.
"""

👉 計算文字列

プラス記号

>>> head = "Hi, "
>>> tail = "nice to meet you."
>>> head + tail
'Hi, nice to meet you.'

乗算

>>> a = 'python'
>>> a * 2
'pythonpython'

文字列の長さを求める

>>> a = "Hi, nice to meet you."
>>> len(a)
21

👉 索引とスライド

索引

>>> a = "Hi, nice to meet you."
>>> a[5]
'i'
>>> a[0]
'H'

>>> a = "Hi, nice to meet you."
>>> a[-1]
'.'
>>> a[-6]
't'

索引

>>> a = "Hi, nice to meet you."
>>> a[0:2]
'Hi'

>>> a = "Hi, nice to meet you."
>>> a[0:2]
'Hi'
>>> a[:2]
'Hi'
>>> a[4:8]
'nice'
>>> a[8:]
' to meet you.'
>>> a[:]
'Hi, nice to meet you.'
>>> a[4:-13]
'nice'

文字列分割

>>> a = "20210529Rainy"
>>> date = a[:8]
>>> weather = a[8:]
>>> date
'20210529'
>>> weather
'Rainy'

👉 文字列マッピング

直接代入数

>>> "I have %d pens." %3
'I have 3 pens.'

文字列の直接代入

>>> "I have %s pens." %"three"
'I have three pens.'

数値を表す変数として入力

>>> number = 3
>>> "I have %d pens." %number
'I have 3 pens.'

2つ以上の値を入力

>>> number = 5
>>> day = "two"
>>> "I have %d pens that i bought %s days ago" %(number, day)

全能%s

>>> "I have %s pens." %5
'I have 5 pens.'
>>>"rate is %s" %90.3
'rate is 90.3'

「%」を含む

>>> "Its possibility is %d%%." %90
'Its possibility is 90%.'

書式コードと数値の使用

>>> "%10s" %"Hi"
        Hi
>>> "%-10sTom" %"Hi"
Hi        Tom

>>> "%0.4f"% 3.141592
'3.1416'
>>> "%10.4f"%3.141592
'    3.1416'

form関数を使用したマッピング

>>> "I have {0} pens".format(3)
'I have 3 pens

>>> "I have {0} pens".format("three")
'I have three pens'

>>> number = 3
>>> "I have {0} pens".format(number)

>>> number = 5
>>> day = "two"
>>> "I have {0} pens that i bought {1} days ago".format(number, day)
'I have 5 pens that i bought two days ago

>>> "I have {number} pens that i bought {day} days ago".format(number = 5, day = "two")
'I have 5 pens that i bought two days ago'

>>> "I have {0} pens that i bought {day} days ago".format(3, day="two")
'I have 3 pens that i bought two days ago'

>>> "{0:<10}".format("Hi")
'Hi        '
>>> "{0:>10}".format("Hi")
'        Hi'
>>>"{0:^10}".format("Hi")
'    Hi    '

>>> "{0:=^10}".format("Hi")
'====Hi===='
>>> "{0:#<10}".format("Hi")
'Hi########'

>>> a = 3.141592
>>> "{0:0.4f}".format(a)
'3.1416'
>>> "{0:10.4f}".format(a)
'    3.1416'

>>> "{{ Hi }}".format()
'{ Hi }'

文字列マッピング

>>> number = 3
>>> day = "two"
>>> f'I have {number} pens that i bought {day} days ago'

'I have 3 pens that i bought two days ago'
>>> f'I have {number + 1} pens that i bought {day} days ago'
'I have 4 pens that i bought two days ago'

>>> d = {'number':3, 'day':'two'}
>>> f'I have {d["number"]} pens that i bought {d["day"]} days ago'
'I have 3 pens that i bought two days ago'

>>> f'{"Hi":<10}'
'Hi        '
>>> f'{"Hi":>10}'
'        Hi'
>>> f'{"Hi":^10}'
'    Hi    '

>>> f'{"Hi":=^10}'
'====Hi===='
>>> f'{"Hi":#<10}'
'Hi########'

>>> a = 3.141592
>>> f'{a:0.4f}'
'3.1416'
>>> f'{a:10.4f}'
'    3.1416'

>>> f'{{ Hi }}'
'{ Hi }'

👉 文字列関連関数(8個)

文字数世紀

>>> a = "bubble"
>>> a.count('b')
3

ヒント位置1(find)

>>> a = "I have 3 pens that i bought two days ago"
>>> a.find('s')
12
>>> a.find('c')
-1

ヒント位置2(index)

>>> a = "I have 3 pens that i bought two days ago"
>>> a.index('s')
12
>>> a.index('c')
Traceback (most recent call last):
  File "main.py", line 1, in <module>
    print(a.index('c'))
ValueError: substring not found

挿入文字列(join)

>>> ",".join('ABCDE')
A,B,C,D,E

大文字と小文字の変更

>>> a = "hi"
>>> a.upper()
'HI'
>>> b = "HI"
>>> b.lower()
'hi'

空白をクリア(lstrip、rstrip、strip)

>>> a = "   Hi   "
>>> a.lstrip()
'Hi   '
>>> a.rstrip()
'   Hi'
>>> a.strip()
'Hi'

置換文字列

>>> a = "My favorite food is pizza"
>>> a.replace('pizza','chicken')
'My favorite food is chicken'

区切り文字列(split)

>>> a = "My favorite food is pizza"
>>> a.split()
['My' ,'favorite' ,'food' ,'is' ,'pizza']
>>> b = "a;b;c;d"
>>> b.split(";")
['a', 'b', 'c', 'd']

文字列の値は変更できません

>>> a = pithon
>>> a[1] = 'y'
Traceback (most recent call last):
  File "main.py", line 2, in <module>
    a[1] = "y"
TypeError: 'str' object does not support item assignment

❗文字列フォーマットコード

100 findとindexの違い