python字符串操作详析

motto = '积善有家，必有余庆。'
# 索引
print(motto[0])
# print(motto[10]) 报错

# 切片  不包含右侧  从小到大
print(motto[0:9])
print(motto[0:10])
print(motto[0:100])
print(motto[0:])
print(motto[-10:])
print(motto[-100:])
print(motto[-5:-1])
print(motto[0:10:2])
print(motto[:5])
print(motto[3:2])  # 若大到小，则返回''
print(motto[2:3])

s = "ILovePython"
# 1. str.count('',起点,终点)
print(s.count('o', 1, 5))
print(s.count('o'))

# 2. str.find('',起点,终点)  找不到返回-1
print(s.find('o',3))
print(s.find('o',3,5))
print(s.find('o'))

# 3. str.index('',起点,终点)   找不到则报错
print(s.index('o'))
print(s.index('Py'))

# 4. str.startswith('',起点,终点)
print(s.startswith("IL"))
print(s.startswith("L"))

# 5. str.endswith('',起点,终点)
print(s.endswith("on"))
print(s.endswith("n"))
print(s.endswith("e"))

1
2
9
-1
2
2
5
True
False
True
True
False

# join()函数  
list_val = ['www', 'baidu', 'com']
str_val = '.'.join(list_val)
print(str_val)

tuple = ('Users', 'andy', 'code')
str_val = '/'.join(tuple)
print(str_val)

# 1. split('',分割次数)   默认从空格 \n \r \t切掉
s = "我 爱\t你\nPy thon"
print(s.split())
s1 = "python我爱你Python"
print(s1.split("y"))
s2 = "python我爱你Python"
print(s1.split("y", 1))

# 2. splitlines()  默认从换行符rt切掉
s = "我 爱\t你\nPy thon"
print(s.splitlines())

# 3. partition('')  不切掉 分成3元素元组
s = "我爱你Python"
print(s.partition('爱'))

['我', '爱', '你', 'Py', 'thon']
['p', 'thon我爱你P', 'thon']
['p', 'thon我爱你Python']
['我 爱\t你', 'Py thon']
('我', '爱', '你Python')

string_val = 'I love Python'
print(string_val.upper())
print(string_val.lower())
print(string_val.title())  # 每个单词第一个字母变大写
print(string_val.capitalize())  # 仅第一个字母变大写
print(string_val.swapcase())

I LOVE PYTHON
i love python
I Love Python
I love python
i LOVE pYTHON

s = "     ILovepython"
print(s)
print(s.strip())
print(s.strip('     I'))
print(s.strip('n'))

s1 = "00000003210Runoob0123000000"
print(s1.strip('0'))
print(s1.lstrip('0'))
print(s1.rstrip('0'))

  ILovepython
ILovepython
Lovepython
3210Runoob0123
3210Runoob0123000000
00000003210Runoob0123