# Python learn note
[TOC]
## Strings
### lower
:::info
用於將字串全部轉為==小寫==
:::
```python=
phrase = " Hello world "
print(phrase.lower)
Python> hello world
```
### upper
:::info
用於將字串全部轉為==大寫==
:::
```python=
phrase = " Hello world "
print(phrase.upper)
Python> HELLO WORLD
```
### isupper
:::info
檢查字串中字母是否全為==大寫==，若全為大寫則回傳==True==，不是則回傳==False==
:::
```python=
phrase = " Hello world "
print(phrase.isupper)
Python> False
```
### islower
:::info
檢查字串中字母是否全為==小寫==，若全為大寫則回傳==True==，不是則回傳==False==
:::
```python=
phrase = " Hello world "
print(phrase.islower)
Python> False
```
### index
:::info
檢查字串中字元之==位置==(<font color=red> 從0開始計算，空白也計算在內，如有重複字母只會回傳第一個 </font>)
:::
```python=
phrase = " Hello world "
print(phrase.index("H"))
Python> 1
```
### replace
:::info
==替換==字串中的字元
:::
```python=
phrase = " Hello world "
print(phrase.replace("H","h"))
Python> hello world
```
## Numbers
:::success
數字可連續運算
:::
### 基本運算
:::info
加減乘除(+、-、*、/)
:::
### 整數除法
:::info
雙斜線( ==//== )
:::
```python=
print(8//6)
Python> 1 #小數點省略
```
### 取餘數
:::info
百分比符號(==%==)
:::
```python=
numbers = 8
print(numbers % 5)
Python> 3 #8/5=1...3
1 ```
### str
:::info
將==數字==型態轉為==字串==型態
:::
```python=
numbers = 8
print("印出數字為" + str(numbers))
Python> 印出數字為8
```
### abs
:::info
將數字取絕對值
:::
```python=
numbers = -8
print(abs(numbers))
Python> 8
```
### pow
:::info
取次方
:::
```python=
print(pow(2,4)) #x的y次方(x,y)
Python> 16
```
### max,min
:::info
取最大(小)值
:::
```python=
print(max(1,4,2323,44,535,100,88,43434))
Python> 43434
```
### round,ceil,floor
:::info
四捨五入,無條件進位,無條件捨去 (後兩者需==import==)
:::
```python=
from math import *
num=123.578
#四捨五入
print(round(num)) #124
#無條件進位
print(ceil(num)) #124
#無條件捨去
print(floor(num)) #123
```
### sqrt
:::info
開根號
:::
```python=
print(sqrt(64))
Python> 8.0
```
## List
:::info
存放多種不同型態資料
:::
### extend
:::info
將列表做延伸
:::
```python=
scores = [90,70,40,42,23]
friends = ["小黑","小白","小黃"]
scores.extend(friends)
print(scores)
Python> [90, 70, 40, 42, 23, '小黑', '小白', '小黃']
```
### insert
:::info
在列表中插入值
:::
```python=
scores = [90,70,40,42,23]
scores.insert(2,30) #在第二位插入30
print(scores)
Python> [90, 70, 30, 40, 42, 23]
```
### remove
:::info
在列表中==刪除==值
:::
```python=
scores = [90,70,40,42,23]
scores.remove(90)
print(scores)
Python> [70, 30, 40, 42, 23]
```
### clear
:::info
清空列表
:::
```python=
scores = [90,70,40,42,23]
scores.clear()
print(scores)
Python> []
```
### sort
:::info
將列表由小到大排列
:::
```python=
scores = [90,70,40,42,23]
scores.sort()
print(scores)
Python> [23, 40, 42, 70, 90]
```
### reverse
:::info
將列表==反轉==
:::
```python=
scores = [90,70,40,42,23]
scores.sort()
print(scores)
Python> [23, 42, 40, 70, 90]
```
### 元組tuple
:::info
與列表類似，使用小括號，但<font color=red>內容無法被新增刪除及修改</font>
:::
## Funciton
### 何為函式
:::info
函式是一段預先寫好的程式碼，幫助我們資料處理與運算，然後回傳給我們想要的資訊
:::
### 函式的定義
:::info
使用def開頭，函式名稱只能為英文大小寫、數字及底線的組合
:::
```python=
def hello():
print("Hello world")
hello()
Python> Hello world
```
:::success
函式是可以傳入參數的
:::
```python=
def hello(name,age):
print("Hello," + name + "\n你今年" + age + "歲")
hello("Roger","22")
Python> Hello,Roger
你今年22歲
```
### 回傳值return
:::info
直接==結束==函式，回傳「資料」，方便繼續在外部運算
:::
```python=
def add(num1,num2):
print(num1 + num2)
return 10
value = add(3,4)
print(value)
Python> 7
10
```
:::success
如果函式中沒有return值，就會回傳==None==
:::
```python=
def add(num1,num2):
print(num1 + num2)
value = add(3,4)
print(value)
Python> 7
None
```
## IF判斷句
### 單純if判斷句
```python=
hungry = True
if hungry:
print("go to eat")
Python> go to eat
```
### if ...else
```python=
rainy = False
if rainy:
print("drive to work")
else:
print("walk to work")
Python> walk to work
```
### if...elif
:::success
一個等號為賦值，兩個等號為比較
:::
```python=
point = 100
if point == 100:
print("got 1000")
elif point >= 80:
print("got 500")
elif point >= 60:
print("got 100")
else:
print("give me 300")
Python> got 1000
```
### if不相等
:::info
使用 != 或 not()
:::
### if判斷句練習
#### 實作max函式
```python=
def max_num(num1, num2, num3):
if num1 >= num2 and num1 >= num3:
return num1
elif num2 >= num1 and num2 >= num3:
return num2
elif num3 >= num1 and num3 >= num2:
return num3
print(max_num(1, 4, 5))
Python> 5
```
#### 實作簡易計算機
```python=
def cal():
num1 = float(input("type first number:"))
op = input("type opration way:")
num2 = float(input("type second number:"))
if op == "+":
print(num1+num2)
elif op == "-":
print(num1-num2)
elif op == "*":
print(num1*num2)
elif op == "/":
print(num1/num2)
else:
print("type error please retry!")
cal()
```
## Dictionary
:::info
許多鍵與值的搭配，使用大括號
:::
```python=
dic = {"蘋果":"apple", "香蕉":"banana", "貓":"cat", "狗":"dog"}
print(dic["蘋果"])
```
## while迴圈應用:實作猜數字遊戲
:::info
設置一謎底讓用戶猜答案，但最多只能猜三次，輸入的數字太大或太小都有提示
:::
```python=
print("welcome to the game")
secret_num = 99
guess = None
guess_limit = 1
while guess_limit <= 3 and guess != secret_num:
guess_limit += 1
guess = int(input("type a number: "))
if guess > secret_num:
print("smaller")
elif guess < secret_num:
print("bigger")
if guess == secret_num:
print("congratulation!")
else:
print("YOU LOSS~")
```
## for迴圈
:::info
for 變數 in 字串或列表
要重複執行的程式碼
:::
### 實作pow函數
```python=
def power(base_num, pow_num):
result = 1
for index in range(pow_num):
result = result * base_num
return result
print(power(2,3))
Python> 8
```
## 二維陣列及巢狀迴圈
:::info
當列表中包含第二個以上的列表時，就稱為二維陣列
:::
```python=
num = [
[0,1,2],
[3,4,5],
[6,7,8],
[9]
]
```
:::info
二維陣列取值方法
:::
```python=
print(num[行][列])
```
:::info
當迴圈內包含第二個以上迴圈時，就稱為巢狀迴圈
:::
### 利用巢狀迴圈在二維陣列取值
```python=
for row in num:
for col in row:
print(col)
Python> 0
1
2
3
4
5
6
7
8
9
```
## 檔案的讀取與寫入
:::info
open("檔案路徑",mode="開啟模式")
:::
:::success
檔案路徑分為==絕對路徑==與==相對路徑==
:::
### 讀取
```python=
file = open("123.txt", mode="r")
print(file.read())
file.close()
```
### 寫入
```python=
with open("123.txt", mode="a", encoding="utf-8") as file:
file.write("\n你好啊")
```
## 實作一問答程式
```python=
from question import Question
test = [
"1. 1+3=?\n(a) 2\n(b) 3\n(c) 4\n\n",
"2. 一公尺等於幾公分?\n(a) 10\n(b) 100\n(c) 1000\n\n",
"3. 香蕉是什麼顏色?\n(a) 黑色\n(b) 黃色\n(c) 白色\n\n"
]
questions = [
Question(test[0], "c"),
Question(test[1], "b"),
Question(test[2], "b"),
]
def run_test(questions):
score = 0
for question in questions:
answer = input(str(question.decription) + "Answer:")
if answer == question.answer:
score += 1
print("You got " + str(score) + " point, in " + str(len(questions)) + " questions")
run_test(questions)
```
:::success
class Question
:::
```python=
class Question:
def __init__(self,description,answer) :
self.decription = description
self.answer = answer
```
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