# Python 第四堂 四則運算、for迴圈
## 加減乘除
```python=
a = 10
b = 5
print(a + b) # 加法
print(a - b) # 減法
print(a * b) # 乘法
print(a / b) # 除法
print(a // b)# 除法,但捨去小數
print(a % b) # 取餘數
print(a ** b)# 次方
```
## 除法及餘數
```python=
a = 13
b = 5
print(a / b) # 除法,會取小數點
print(a // b)# 除法,但捨去小數
print(a % b) # 取餘數 被b除餘...
```
```python=
for i in range(100):
if i % 5 == 2:
print(i)
```
## sum 累加
```python=
# sum用法
array = [5, 6, 7]
print(sum(array))
# sum()是python內建的函式,這邊用s命名避免衝突
s = 0
for i in range(101):
s += i # s = s + i
print(s)
```
## 用list來儲存 1加到100的結果
```python=
l = list()
s = 0
for i in range(101):
s += i # s = s + i
l.append(s)
# print(l)
for i in l:
print(i)
```
## input 使用者輸入
```python=
a = 5
print(a)
a = input("請輸入數字: ")
print(a)
```
### input 接收到的為字串格式
```python=
a = int(input("請輸入數字: "))
print("您輸入的數字:", a)
for i in range(1, a+1):
print(i)
```
### type 格式
```python=
a = input("請輸入數字: ")
print(type(a))
b = 6
print(type(b))
```
## 判斷是否為數字 isdigit
```python=
a = "123"
print(a.isdigit())
a = "12AB3"
print(a.isdigit())
```
## 判斷是否為英文字母 isalpha
```python=
a = "ABC"
print(a.isalpha())
a = "12AB3"
print(a.isalpha())
```
## 中華民國身分證字號
```python=
ID = "A123456789"
print(ID[0].isalpha())
print(ID[1:10].isdigit())
#for c in ID: # char
# print(c.isdigit())
```
```python=
ID = input("請輸入身份證字號:")
if len(ID) == 10: # 判斷長度
if ID[0].isalpha() and ID[1:10].isdigit(): # 再判斷字母及數字
print("您輸入的格式正確", ID)
else:
print("格式錯誤", ID)
else:
print("身分證字號長度不符")
```