[Python] 파이썬 반복문에 대해서 알아보자. (for문)

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이번 시간에는 파이썬의 반복문 대해서 알아보는 시간을 갖겠다.

 

1. for 문

 - for문에 사용가능한 자료형 : 문자열, 리스트, 튜플, 집합, 사전
 - for문에 사용가능한 함수 : range, reversed, enumerate, filter, map, zip

 

 

기본 예제 1

for a1 in range(5):
    print("a1 is :", a1)

Result

a1 is : 0
a1 is : 1
a1 is : 2
a1 is : 3
a1 is : 4

 

 

기본 예제 2

for a2 in range(1, 6):
    print("a2 is :", a2)

Result

a2 is : 1
a2 is : 2
a2 is : 3
a2 is : 4
a2 is : 5

 

 

기본 예제 3

for a3 in range(1, 6, 2):
    print("a3 is :", a3)

Result

a3 is : 1
a3 is : 3
a3 is : 5

 

 

 

 

① 예제 1

names = ["Kim", "Park", "Cho", "Lee", "Choi", "Yoo"]

for name in names:
    print("You are", name)

Result

You are Kim
You are Park
You are Cho
You are Lee
You are Choi
You are Yoo

 

 

 

② 예제 2

lotto_numbers = [11, 19, 21, 28, 36, 37]

for number in lotto_numbers:
    print("Your number", number)

Result

Your number 11
Your number 19
Your number 21
Your number 28
Your number 36
Your number 37

 

 

③ 예제 3

word = 'dreams'

for s in word:
    print('word : ', s)

Result

word :  d
word :  r
word :  e
word :  a
word :  m
word :  s

 

 

④ 예제 4

my_info = {
    "name": "Kim",
    "age": 33,
    "city": "Seoul"
}

for key in my_info:
    print(key, ":", my_info[key])

for val in my_info.values():
    print(val)

Result

name : Kim
age : 33
city : Seoul
Kim
33
Seoul

 

 

⑤ 예제 5

name = 'KennRY'

for n in name:
    if n.isupper():
        print(n)
    else:
        print(n.upper())

numbers = [14, 3, 4, 7, 10, 24, 17, 2, 33, 15, 34, 36, 38]

Result

K
E
N
N
R
Y

 

 

⑥ break 문

numbers = [14, 3, 4, 7, 10, 24, 17, 2, 33, 15, 34, 36, 38]

for num in numbers:
    if num == 33:
        print("found : 33!")
        break
    else:
        print("not found : ", num)

Result

not found :  14
not found :  3
not found :  4
not found :  7
not found :  10
not found :  24
not found :  17
not found :  2
found : 33!

⑦ continue 문

lt = ["1", 2, 5, True, 4.3, complex(4)]

for v in lt:
    if type(v) is float:
        continue

    print("type:", type(v))
    print("multiply by 2:", v * 3)

Result

type: <class 'str'>
multiply by 2: 111
type: <class 'int'>
multiply by 2: 6
type: <class 'int'>
multiply by 2: 15
type: <class 'bool'>
multiply by 2: 3
type: <class 'complex'>
multiply by 2: (12+0j)

 

⑧ for else 문

- else 구문 : 반복문이 정상적으로 수행 된 경우 else 블럭 수행 (break로 나오면 실행 안함)

numbers = [14, 3, 4, 7, 10, 24, 17, 2, 33, 15, 34, 36, 38]

for num in numbers:
    if num == 33:  # 45
        print("found : 33!")
        break
    else:
        print("not found : ", num)
else:
    print("Not Found 39...")

Result

not found :  14
not found :  3
not found :  4
not found :  7
not found :  10
not found :  24
not found :  17
not found :  2
found : 33!

 

⑨ 중첩 for 문

for i in range(1, 11):
    for j in range(1, 11):
        print('{:4d}'.format(i * j), end='')

Result

not found :  14
not found :  3
not found :  4
not found :  7
not found :  10
not found :  24
not found :  17
not found :  2
found : 33!