字符串内建函数

find函数查找

strint_example = "hello world good night"
index = strint_example.find("good")
print(index)
12

index函数检索

strint_example = "hello world good night"
index = strint_example.index("good",0,10)#从零开始检索good是否包含在内
print(index)
Traceback (most recent call last):
  File "E:/pycharm202.2.3/pythonProject1/demo1.py", line 2, in <module>
    index = strint_example.index("good",0,10)
ValueError: substring not found

Process finished with exit code 1

如果包含就不报错
strint_example = "hello world good night"
index = strint_example.index("good",1,17)
print(index)
12    #包含运行的结果

count函数基数

strint_example = "hello world good night"
result = strint_example.count("good")
print(result)
1

replace函数替换

strint_example = "hello world good night"
new_string = strint_example.replace("night","evening",1)	#1代表替换次数，不能超过这个次数
print(new_string)
hello world good evening

split函数分隔符

strint_example = "hello world good night"
print(strint_example.split())
print(strint_example.split("e",1))
print(strint_example.split("h"))
['hello', 'world', 'good', 'night']
['h', 'llo world good night']
['', 'ello world good nig', 't']

capitalize首字母大写其他小写

old_string = "hello World Good Night"
new_string = old_string.capitalize()
print(new_string)
Hello world good night

title函数标题化（所有单词都是大写开始，其余均为小写）

old_string = "hello World Good Night"
new_string = old_string.title()
print(new_string)
Hello World Good Night

startwith（检索字符窜是否是指定字符串开头）

old_string = "hello World Good Night"
new_string = old_string.startswith("hello")
print(new_string)
True

endwith检索结尾

old_string = "hello World Good Night"
new_string_one = old_string.endswith("Night")
new_string_tow = old_string.endswith("night")
print(new_string_one)
print(new_string_tow)
True
False

upper函数

old_string = "hello World Good Night"
new_string = old_string.upper()
print(new_string)
HELLO WORLD GOOD NIGHT

ljust（rjust）函数（字符串左对齐）

old_string = "hello World Good Night"
new_string = old_string.ljust(30,'-')	#  宽度为30，单引号里面为剩余位置的情况
print(new_string)
hello World Good Night--------

old_string = "hello World Good Night"
new_string = old_string.rjust(30,'-')
print(new_string)
--------hello World Good Night

lstrip（rstrip）截掉左/右边空格或者指定字符

old_string_one = "     hello World Good Night"
old_string_tow = "hello World Good Night     "
new_string_one = old_string_one.lstrip()
new_string_tow = old_string_tow.rstrip()
print(new_string_one)
print(new_string_tow)
hello World Good Night
hello World Good Night