データ構造でーたこうぞう:文字列もじれつ

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文字列(String)

  • 出力フォーマット
    -endオプション値出力
    使用-%出力
    -使用する出力
    -f文字列フォーマット
    Ex. end option
    ```
print("Hello Python", end='')
print("Hello Python", end='\n') 	# default : end='\n' 
```
    出力値
    ```
Hello PythonHello Python
```
    Ex. using %
    ```
# %s(str) / %f(float) / %d(integer) / %c(character)
# -------------------
print("Hello! %s" %('James'))
print("%.3f" %(3.1415))
print("%d" %(12.5))
print("%c" %('a'))
```
    出力値
    ```
Hello! James
3.142
12
a
```
    Ex. using {}
    ```
print("Welcome to {}".format('파이썬'))
print("Welcome to {}".format('3.14'))
print("Welcome to {}".format('12'))
print("Welcome to {}".format('w'))
print("Welcome to {} {} {}".format('파이썬', 3.14, '아'))
print("my favorite movie is {:03d}".format(7))
print("원주율은 ? {:.2f}".format(3.141592))
```
    出力値
    ```
Welcome to 파이썬
Welcome to 3.14
Welcome to 12
Welcome to w
Welcome to 파이썬 3.14 아
my favorite movie is 007
원주율은 ? 3.14
```
    Ex. f formating
    ```
name = John
age = 15
PI = 3.141592
print(f"My name is {name}, and I'm {age}years old.")
print(f"PI = {PI:.2f}"
```
    出力値
    ```
My name is John, and I'm 15years old.
PI = 3.14
```
  • indexing/slicing
    - index order starts at '0'
    - index reverse order starts at '-1'

    Ex.
    ```
my_str = "python"
# -------------------
# indexing
# my_str[0] = p
# my_str[4] = o
# my_str[-1] = n
# -------------------
# slicing
# my_str[1:4] = yth
# my_str[:] = python
# my_str[2:] = thon
# my_str[:4] = pyth
# my_str[-2:] = on
# my_str[-4:-1] = tho
# my_str[-4:1] = ' ' space
# my_str[0:6:2] = pto ; step = 2
# my_str[::2] = pto ; :: means all, and step = 2
# my_str[::-1] = nohtyp ; step = -1 means reverse step 1
```
  • Str functions 1) split, join
    - split() : use it when you want to split the str
    - join() : use it when you want to join the list
    Ex.
    ```
movies = "미나리, 경계선, 기생충, 학교"
# ------------------------------------------------
movieList = movies.split(",")
# movieList = ['미나리', '경계선', '기생충', '학교']
# ------------------------------------------------
movie = ''.join(movieList)
# movie = "미나리 경계선 기생충 학교"
```
  • Str functions 2) lower, upper
    - lower() : makes all characters in the string lowercase
    - upper() : makes all characters in the string uppercase
    Ex.
    ```
a = "This is an apple"
#
print(a.lower())	# this is an apple
print(a.upper()) 	# THIS IS AN APPLE
```
  • Str functions 3) startswith, endswith
    - startswith("==") : return T/F : if str starts with "=="
    - endswith("==") : return T/F : if str ends with "=="
    Ex.
    ```
a = "01_star.png"
#
print(a.startswith("01"))	# True
print(a.endswith("png"))	# True
```
  • Str functions 4) replace
    - replace("==", "--") : replace "=="(in the string) with "--"
    Ex.
    ```
a = "01_sample.png"
a = a.replace("png", "mp3")
# a = "01_sample.mp3"
```
  • Str functions 5) lstrip, rstrip, strip
    - lstrip() : remove left-side spaces in the string
    - rstrip() : remove right-side spaces in the string
    - strip() : remove both-side spaces in the string
    Ex.
    ```
a = "     01_sample.png"
b = "01_sample.png     "
c = "     01_sample.png     "
#
a = a.lstrip()	# a = "01_sample.png"
b = b.rstrip()	# b = "01_sample.png"
c = c.strip()	# c = "01_sample.png"
```
    • Mysqlの最初のステップ-データの処理
    なぜReactにはKeyが必要なの?