python语法31[string的print和format]

一 string与引号

Python中的字符串可以使用四种引号来表示，‘(单引号)，“（双引号），’‘'（三单引号），"""（三双引号）。 且他们均有相同的意思，需成对出现，单双引号可以相互嵌套。没有任何区别。

>>> print('he said "good", you said "great", and i want to say """excellent"""')
he said "good", you said "great", and i want to say """excellent"""
二 string的join和split函数

#string compare
cmpStr = "abc"
if cmpStr == "abc":
print ("abc" + " Matches " + cmpStr)
if cmpStr.upper() == 'abc'.upper():
print (cmpStr + ' Matches ' + 'ABC'+ ' whit ignoring case')
#abc Matches abc
#abc Matches ABC whit ignoring case

#string join
wordList = ["A", "few", "more", "good", "words"]
print ("List: " + ' '.join(wordList))
#List: A few more good words

#string split
sentence = "A Simple Sentence."
print (sentence.split())
#['A', 'Simple', 'Sentence.']

三 字符串的子串查找和替换

#string find
searchStr = "Red Blue Violet Green Blue Yellow Black"
print (searchStr.find("Red"))
print (searchStr.rfind("Blue"))
print (searchStr.index("Blue"))
print (searchStr.index("Blue",20))
print (searchStr.rindex("Blue"))
print (searchStr.rindex("Blue",1,18))

f='file.py'
if f.endswith('.py'):
print ("Python file: " + f)
elif f.endswith('.txt'):
print ("Text file: " + f)

#string replace
question = "What is the air speed velocity of an unlaiden swallow?"
question2 = question.replace("swallow", "European swallow")
print(question2)

对于子字符串的查找，可以使用in，可读性更好。

if 'hello world,hello'.find('world') != -1 : print('find')
if 'world' in 'hello world,hello' : print('find')

四 print函数中str的格式

#string rjust and ljust
chapters = {1:5, 2:46, 3:52, 4:87, 5:90}
for x in chapters:
print ("Chapter " + str(x) + str(chapters[x]).rjust(15,'.'))
#Chapter 1..............5
#Chapter 2.............46
#Chapter 3.............52
#Chapter 4.............87
#Chapter 5.............90

#print
name='buddy'
print("welcome" + " " + name + ", you are very handsome!" )
print("welcome", name, ", you are very handsome!" )
print('welcome %s, you are very handsome!' %name)
#welcome buddy, you are very handsome!
#welcome buddy , you are very handsome!
#welcome buddy, you are very handsome!

#print string format
chapters2 = {1:5, 2:46, 3:52, 4:87, 5:90}
for x in chapters2:
print ("Chapter %d %15s" % (x,str(chapters2[x])))
#Chapter 1 5
#Chapter 2 46
#Chapter 3 52
#Chapter 4 87
#Chapter 5 90
print函数中使用%来隔离格式str和变量。

五 使用str.format来格式字符串

p4newuser = 'BBB'

p4newuseremail = 'BBB@example.com'
p4newuserfullname = 'BBB Frist'
userspec = str.format("\
User: %s \n\
Email: %s \n\
Update: \n\
Access: \n\
FullName: %s \n\
Password: \n\
" % (p4newuser,p4newuseremail,p4newuserfullname))

print userspec
结果：

User: BBB
Email: BBB@example.com
Update:
Access:
FullName: BBB Frist
Password:

完！