2.Python字符串基础

split,join,strip,replace,lower,upper,capitalize

1.字符串。

print("{0:s}".format('I\'m enjoying learning python.')) #双引号包含，不需要反斜杠。'
print("{0:s}".format("I'm enjoying learning python."))
print("{0:s}".format('''you can use triple single quotes
for multi-line comment strings.'''));   #这个会自然换行。
print("{0:s}".format("""you can use triple single quotes
for multi-line comment strings."""));   #这个会自然换行。


I'm enjoying learning python.
I'm enjoying learning python.
you can use triple single quotes
for multi-line comment strings.
you can use triple single quotes
for multi-line comment strings. 

#当使用3个单引号或这三个双引号则不需要使用反斜杠。

string1="This is a "
string2="short string."
sentence=string1+string2
print("{0:s}".format(sentence))
print("{0:s}{1:s}{2:s}".format("She is ","very "*4,"beautiful."))

This is a short string.
She is very very very very beautiful.

m=len(sentence)
print("{0:d}".format(m))

+:可以将字符串相加。
*:操作符可以将字符串重复一定的次数。

7.split 函数
#split 函数：
split 函数可以再括号中使用两个附加参数。
第一个附加参数表示使用哪个字符进行拆分
第二个附加参数表示进行拆分的次数。

string1="My deliverable is due in May"
string1_list1=string1.split()
string1_list2=string1.split(" ",2)  #只想对前两个空格做拆分,后面的不做拆分。
print("{0}".format(string1_list1))
print("{0}".format(string1_list2)) 
print("First price:{0} Second price:{1} Third price:{2}".format(string1_list2[0],string1_list2[1],string1_list2[2]))
string2="Your,deliverable,is,due,in,June"
string2_list=string2.split(',')
print("{0}".format(string2_list))
print("{0} {1} {2}".format(string2_list[1],string2_list[5],string2_list[-1]))

#['My', 'deliverable', 'is', 'due', 'in', 'May']
#['My', 'deliverable', 'is due in May']
#First price:My Second price:deliverable Third price:is due in May
#['Your', 'deliverable', 'is', 'due', 'in', 'June']
#deliverable June June

#没有附加参数，所以split函数使用空格字符(默认值)对字符串进行拆分。
#附加参数是个逗号，split函数在出现逗号的位置拆分字符串。

2.join 
print("{0}".format(','.join(string2_list)))
#Your,deliverable,is,due,in,June
#使用逗号将集合中的每个字符串组成一个字符串。

3.strip 
strip,lstrip,rstrip 
#从字符串删除不想要的字符。

string3=" Remove unwanted characters from this string.\t\t \n"
print("string3:{0:s}".format(string3))
string3_lstrip=string3.lstrip()
print("lstrip:{0:s}".format(string3_lstrip))
string3_rstrip=string3.rstrip()
print("rstip:{0:s}".format(string3_rstrip))
string3_strip=string3.strip()
print("strip:{0:s}".format(string3_strip))


#string3: Remove unwanted characters from this string.        #原样输出。 
#lstrip:Remove unwanted characters from this string.    #删除左边空格。     
#rstip: Remove unwanted characters from this string.    #删除右边空格。
#strip:Remove unwanted characters from this string.     #删除两个空格。


string4="$$Here's another string that has unwanted characters.__---++"
print("{0:s}".format(string4))
string4_strip=string4.strip('$_-+')
print("{0:s}".format(string4_strip))

#$$Here's another string that has unwanted characters.__---++
#Here's another string that has unwanted characters.
#strip删除字符串两端的：$,_,-,+ 四种字符。

4.replace 
#第一个字符是字符串中查找要替换的字符或字符串
#第二个位置是新的字符或字符串。

 

string5="Let's replace the spaces in this sentence with other characters."
string5_replace=string5.replace(" ","!@!")   #将空格替换为"!@!"
print("{0:s}".format(string5_replace))
string5_replace=string5.replace(" ",",")     #将空格替换为逗号。
print("{0:s}".format(string5_replace))
#Let's!@!replace!@!the!@!spaces!@!in!@!this!@!sentence!@!with!@!other!@!characters.
#Let's,replace,the,spaces,in,this,sentence,with,other,characters.

5.lower,upper,capitalize

string6="Here's WHAT Happens WHEN You Use lower."
print("{0:s}".format(string6.lower()))
print("{0:s}".format(string6.upper()))
print("{0:s}".format(string6.capitalize())) #字符串第一个字母大写，其他小写。
string5="Let's replace the spaces in this sentence with other characters."
string5_list=string5.split()
for word in string5_list:
    print("{0:s}".format(word.capitalize()))

here's what happens when you use lower.
HERE'S WHAT HAPPENS WHEN YOU USE LOWER.
Here's what happens when you use lower.
Let's
Replace
The
Spaces
In
This
Sentence
With
Other
Characters.