Article directory
count
Returns the number of occurrences strin between startand .endmystr
Grammar format:
S.count(sub[, start[, end]]) -> int
Example:
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.count('好')) # 3. '好' 字出现三次
replace
Replaces what is specified in the string, countup to counttimes if specified.
mystr = '今天天气好晴朗，处处好风光呀好风光'
newstr = mystr.replace('好', '坏')
print(mystr) # 今天天气好晴朗，处处好风光呀好风光 原字符串未改变！
print(newstr) # 今天天气坏晴朗，处处坏风光呀坏风光 得到的新字符串里，'好' 被修改成了 '坏'
newstr = mystr.replace('好', '坏', 2) # 指定了替换的次数
print(newstr) # 今天天气坏晴朗，处处坏风光呀好风光 只有两处的 '好' 被替换成了 '坏'
content separation
Content separation mainly involves four methods of split, splitlines, partitionand .rpartition
split
Slice with the specified string as the delimiter, and if maxsplithas the specified value, only maxsplit+1substrings will be separated. The returned result is a list.
mystr = '今天天气好晴朗，处处好风光呀好风光'
result = mystr.split() # 没有指定分隔符，默认使用空格，换行等空白字符进行分隔
print(result) # ['今天天气好晴朗，处处好风光呀好风光'] 没有空白字符，所以，字符串未被分隔
result = mystr.split('好') # 以 '好' 为分隔符
print(result) # ['今天天气', '晴朗，处处', '风光呀', '风光']
result = mystr.split("好", 2) # 以 '好' 为分隔符，最多切割成 3 份
print(result) # ['今天天气', '晴朗，处处', '风光呀好风光']
rsplit
The usage is splitbasically the same as that of , except that they are separated from right to left.
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.rsplit('好', 1)) # ['今天天气好晴朗，处处好风光呀', '风光']
split lines
Separated by line, return a list containing each line as an element.
mystr = 'hello \nworld'
print(mystr.splitlines())
partition
Divide mystrwith strinto three parts, strbefore, strand strafter, the three parts form a tuple.
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.partition('好')) # ('今天天气', '好', '晴朗，处处好风光呀好风光')
rpartition
Similar to partition()the function, but starts from the right.
mystr = '今天天气好晴朗，处处好风光呀好风光'
print(mystr.rpartition('好')) # ('今天天气好晴朗，处处好风光呀', '好', '风光')
Modify capitalization
The function of modifying capitalization is only valid for English, mainly including capitalizing the first letter capitalize, capitalizing the first letter of each word title, all lowercase lower, and all uppercase upper.
capitalize
Capitalize the first letter of the first word.
mystr = 'hello world'
print(mystr.capitalize()) # Hello world
title
Capitalize the first letter of each word.
mystr = 'hello world'
print(mystr.title()) # Hello World
lower
All become lowercase.
mystr = 'hElLo WorLD'
print(mystr.lower()) # hello world
upper
All become uppercase.
mystr = 'hello world'
print(mystr.upper()) # HELLO WORLD
Space handling
Python provides us with various methods for manipulating tables in strings.
1. ljust
Returns a string of the specified length, padded on the right with blank characters (left justified).
str = 'hello'
print(str.ljust(10)) # hello 在右边补了五个空格
2. rjust
Returns a string of the specified length, padded on the left with blank characters (right justified).
str = 'hello'
print(str.rjust(10)) # hello在左边补了五个空格
3. center
Returns a string of the specified length, with whitespace padding at both ends (center-aligned).
str = 'hello'
print(str.center(10)) # hello 两端加空格，让内容居中
4. lstrip
Remove mystrwhitespace characters to the left.
mystr = ' he llo '
print(str.lstrip()) # he llo 只去掉了左边的空格，中间和右边的空格被保留
5. rstrip
Remove mystrwhitespace characters to the right.
mystr = ' he llo '
print(str.rstrip()) # he llo右边的空格被删除
6. strip
Removes two breaking whitespace characters.
str = ' he llo '
print(str.strip()) # he llo
string concatenation
Traverse the parameters, take out each item in the parameter, and then add it later mystr.
Grammar format:
S.join(iterable)
Example:
mystr = 'a'
print(mystr.join('hxmdq')) # haxamadaq 把 hxmd 一个个取出，并在后面添加字符 a. 最后的 q 保留，没有加 a
print(mystr.join(['hi', 'hello', 'good'])) # hiahelloagood
Function: You can quickly convert a list or tuple into a string and separate it with specified characters.
txt = '_'
print(txt.join(['hi', 'hello', 'good'])) # hi_hello_good
print(txt.join(('good', 'hi', 'hello'))) # good_hi_hello
string operators
The addition operator can be used between strings to concatenate two strings into one string. For example: 'hello' + 'world'the result of is 'helloworld'.
Multiplication can be done between strings and numbers, and the result is to repeat the specified string multiple times. For example: 'hello' * 2the result of is 'hellohello'.
Between strings, if a comparison operator is used for calculation, the code corresponding to the character will be obtained and then compared.
In addition to the above-mentioned operators, strings do not support other operators by default.
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