几个有用的python字符串函数(format,join,split,startwith,endwith,lower,upper)

format

字符串的format函数为非字符串对象嵌入字符串提供了一种非常强大的方法。在format方法中&＃xff0c;字符串使用{}来代替一系列字符串的参数并规定格式。下面通过几个例子来详细解释其用法

直接使用{}

apple_num &＃61; 10
print("I have {} apples".format(apple_num))


在{}中使用位置参数1

nums &＃61; [4, 5, 6]
msg &＃61; "Numbers: {0} {1} {0}".format(nums[0], nums[1])
print(msg)
# Numbers: 4 5 4


在{}中使用位置参数2

msg &＃61; "Numbers: {a} {c} {b}".format(a&＃61;5, b&＃61;6, c&＃61;7)
print(msg)
# Numbers: 5 7 6


{}中的更多格式

_ &＃61; [print("{}x{}&＃61;{:<4}".format(y, x, x*y), end&＃61;"\n" if x&＃61;&＃61;y else "") for x in range(1, 10) for y in range(1, x&＃43;1)]


:<4表示左对齐占用四格位置&＃xff0c;其结果为&＃xff1a;

1x1&＃61;1
1x2&＃61;2 2x2&＃61;4
1x3&＃61;3 2x3&＃61;6 3x3&＃61;9
1x4&＃61;4 2x4&＃61;8 3x4&＃61;12 4x4&＃61;16
1x5&＃61;5 2x5&＃61;10 3x5&＃61;15 4x5&＃61;20 5x5&＃61;25
1x6&＃61;6 2x6&＃61;12 3x6&＃61;18 4x6&＃61;24 5x6&＃61;30 6x6&＃61;36
1x7&＃61;7 2x7&＃61;14 3x7&＃61;21 4x7&＃61;28 5x7&＃61;35 6x7&＃61;42 7x7&＃61;49
1x8&＃61;8 2x8&＃61;16 3x8&＃61;24 4x8&＃61;32 5x8&＃61;40 6x8&＃61;48 7x8&＃61;56 8x8&＃61;64
1x9&＃61;9 2x9&＃61;18 3x9&＃61;27 4x9&＃61;36 5x9&＃61;45 6x9&＃61;54 7x9&＃61;63 8x9&＃61;72 9x9&＃61;81

join()

joins a list of strings with another string as a separator

print(", ".join(["spam", "eggs", "ham"]))
# spam, eggs, ham


更多见避免使用“&＃43;”操作符在python中连接字符串

split

join的逆向

print("spam, eggs, ham".split(", "))
# [&＃39;spam&＃39;, &＃39;eggs&＃39;, &＃39;ham&＃39;]


replace()

replaces one substring in a string with another

print("Hello ME".replace("ME", "world")
# Hello world


startwith, endwith

determine if there is a substring at the start and end of a string, respectively.

print("This is a sentence".startwith("This"))
# True
print("This is a sentence".endwith("sentence"))
# False


lower, upper

change the case of a string

print("hello world".upper())
# HELLO WORLD
print("HELLO WORLD".lower())
# hello world