# 字符串类型内置方法
# 字符串类型
## 用途：名字，兴趣，爱好
## 定义方式
```python
name1 = 'nick'
name2 = "nick"
name3 = """
nick
"""
name4 = '''
nick
'''
```
# 常用操作和内置方法
## 优先掌握
### 按索引取值
```python
#1 按索引取值
zhuping_info_list = ['zhuping',190,140,["piao","feiji","2333"]]
print(zhuping_info_list[0])
zhuping_info = 'zhuping 190 140 ["piao","feiji","2333"]'
print(zhuping_info[6])
```
```
zhuping
g
```
### 切片（顾头不顾尾），步长的正负控制行进的方向，往左还是往右
```python
print(zhuping_info[:])
print(zhuping_info[0:7])
print(zhuping_info[0:7:2])# 2是步长
print(zhuping_info[0:7:-1])
print(zhuping_info[-1:-3])
print(zhuping_info[-1:-3:-1])
print(zhuping_info[-3:-1])
print(zhuping_info[-3:])
```
```
zhuping 190 140 ["piao","feiji","2333"]
zhuping
zuig
```
```
]"
3"
3"]
```
### 长度
```python
print(len(zhuping_info))
```
```
39
```
### 成员运算 in/not in
```python
print('zhuping' in zhuping_info)
print('nick' in zhuping_info)
```
```
True
False
```
### 移除空白strip 默认空格
```python
abc = ' a abc a'
print(abc)
print(abc.strip())# 移除左右两端
print(abc.strip('a'))# 移除左右两端的a
```
```
a abc a
a abc a
a abc
```
### 切分 split
```python
zhuping_info = 'zhuping 190 140 ["piao","feiji","2333"]'
print(zhuping_info.split(' '))
print(zhuping_info.split(' ',1))
```
```
['zhuping', '190', '140', '["piao","feiji","2333"]']
['zhuping', '190 140 ["piao","feiji","2333"]']
```
### 循环
```python
zhuping_info = 'zhuping 190 140 ["piao","feiji","2333"]'
for i in zhuping_info:
print(i)
```
```
z
h
u
p
i
n
g
1
9
0
1
4
0
[
"
p
i
a
o
"
,
"
f
e
i
j
i
"
,
"
2
3
3
3
"
]
```
## 需要掌握（本周必须掌握）
### lstrip&rstrip
```python
zhuping_info = '&&&&&&&zhuping 190 140["piao","feiji","23333"]&&&&&&&&'
print(zhuping_info.lstrip('&'))# 左
print(zhuping_info.rstrip('&'))# 右
```
```
zhuping 190 140["piao","feiji","23333"]&&&&&&&&
&&&&&&&zhuping 190 140["piao","feiji","23333"]
```
### lower & upper
```python
print(zhuping_info.lower())# 小写
print(zhuping_info.upper())# 大写
```
```
&&&&&&&zhuping 190 140["piao","feiji","23333"]&&&&&&&&
&&&&&&&ZHUPING 190 140["PIAO","FEIJI","23333"]&&&&&&&&
```
### startswith&endswith
```python
zhuping_info = '&&&&&&ZhuPing 190 140 ["Piao","Feiji","2333"]&&&&&&'
print(zhuping_info.startswith('&&&&&&Z'))#判断开头结尾
print(zhuping_info.endswith('&&&&&&Z'))
```
```
True
False
```
### rsplit
```python
print(zhuping_info.rsplit(' '))
print(zhuping_info.rsplit(' ',1))
```
```
['&&&&&&ZhuPing', '190', '140', '["Piao","Feiji","2333"]&&&&&&']
['&&&&&&ZhuPing 190 140', '["Piao","Feiji","2333"]&&&&&&']
```
### join
```python
zhuping_info_split = zhuping_info.rsplit(' ')
print(','.join(zhuping_info_split))
```
```
&&&&&&ZhuPing,190,140,["Piao","Feiji","2333"]&&&&&&
```
### replace 替换
```python
print(zhuping_info.replace('ZhuPing','ruixing').replace('Feiji','BigFeiji'))
```
```
&&&&&&ruixing 190 140 ["Piao","BigFeiji","2333"]&&&&&&
```
### isdigit 判断是否为数字
```python
print('10asfdsdsfdsd'.isdigit())
print('10'.isdigit())
```
```
False
True
```
## 了解
### find|rfind|index|rindex|count
```python
ruixing_info = 'RUIxing feiji BIGFEIJI feiji feiji huojimian'
# 这里用0和-1 代表true和false
print(ruixing_info.find('RUIxing')) # 从左边开始找
print(ruixing_info.find('RUIxing1'))
print(ruixing_info.rfind('RUIxing'))# 从右边开始找（常用于大项目中节省时间）
print(ruixing_info.rfind('RUIxing1'))
```
```
0
-1
0
-1
```
```python
print(ruixing_info.index('RUIxing')) # （索引）
# print(ruixing_info.index('RUIxing1')) # 错
print(ruixing_info.rindex('RUIxing')) # （从右开始找）
# print(ruixing_info.rindex('RUIxing1')) # 错
print(ruixing_info.count('feiji')) # 总计数量
print(ruixing_info.count('BIGFEIJI'))
```
```
0
0
3
1
```
### center|ljust|rjust|zfill
```python
print('nick'.center(50, '-')) # 一共从头到尾字符50个 当左右两边差1时 默认右边多1
print('nic'.center(50, '-'))
print('nick'.ljust(50, '0')) # 最左边
print('nick'.rjust(50, '0')) #最右边
print('nick'.zfill(50))
```
```
-----------------------nick-----------------------
-----------------------nic------------------------
nick0000000000000000000000000000000000000000000000
0000000000000000000000000000000000000000000000nick
0000000000000000000000000000000000000000000000nick
```
### expandtabs
```python
print(' NiCk'.expandtabs(2)) # 空格
转行
print(' NiCk
'.expandtabs(32))
print(' NiCk'.expandtabs(8))
```
```
NiCk
NiCk
NiCk
```
### captalize|swapcase|title
```python
print('nick nicK'.capitalize()) # 第一个字母大写
print('nick nicK'.swapcase()) # 全大写
print('nick nicK'.title()) # 每个单词首字母大写
```
```
Nick nick
NICK NICk
Nick Nick
```
## is系列
```python
'nick'.isdigit()
print('nick'.isalpha()) #判断是否为字母
print('10'.isalpha())
```
```
True
False
```
##
存一个值or多个值：一个值
有序or无序（有索引为有序，否则为无序）：有序
可变or不可变：不可变
```python
name = 'nick'
print(id(name))
name += 'handsome'
print(id(name))
```
```
74655520
75307432
```
### 仅作了解
```python
print('D:飞秋数据视频+课件Python基础nick day 02')
print(f'D:飞秋数据视频+课件Python基础nick\tday 02{name}')
print(r'D:飞秋数据视频+课件Python基础nick day 02')
print(type('D:飞秋数据视频+课件Python基础nick\tday 02'))
print(type(u'D:飞秋数据视频+课件Python基础nick\tday 02'))
print(type(b'D:\xe9xa3x9exe7xa7'))
```