python—字符串string

字符串的使用在python等编程语言中极为广泛，其使用技巧收录如下。

# strip去除空格

s = ' abcd efg '
print(s.strip()) #去除空格
print(s.lstrip()) #去除左边空格
print(s.rstrip()) #去除右边空格
print(s)
python—字符串string

# 字符串连接

print('abc_' + 'defg')

s = 'abcdefg'
s += '\nhijk'
print(s)
python—字符串string

# 大写小

s = 'abc defg'
print(s.upper())
print(s.upper().lower())
print(s.capitalize()) # 首字母大写
python—字符串string

# 位置和比较

s_1 = 'abcdefg'
s_2 = 'abdefgh'
print(s_1.index('bcd'))

python—字符串string

try:

print(s_1.index('bce'))
except ValueError:
print('ValueError: substring not found')

print(s_1 == s_1) # cmp函数被Python3移除了

print(s_1 > s_2)
print(s_2 > s_1)

# 分割和连接，此用法非常频繁，要熟记

s = 'abc,def,ghi'
print(s.split(','))

t = '123\n456\n789'

numbers = t.splitlines()
print(numbers)
print('-'.join(numbers))
python—字符串string

# 常用判断

s = 'abcdefg'
print(s.startswith('abc'))
print(s.endswith('efg'))
print('abcd1234'.isalnum())
print('\tabcd1234'.isalnum())
print('abcd'.isalpha())
print('12345'.isdigit())
print(' '.isspace())
print('acb125'.islower())
print('A1B2C'.isupper())
print('Hello world!'.istitle())
python—字符串string

# 数字到字符串

print(str(5))
print(str(5.))
print(str(-5.23))
print(int('1234'))
print(float('-23.456'))
python—字符串string

# 格式化字符串

print('Hello %s!' % 'world')

print('%d-%.2f-%s' % (4, -2.3, 'hello'))

python—字符串string