Learn Python By Practice — string，pythonpractice,import sys#

Learn Python By Practice — string，pythonpractice,import sys#

import sys# coding: UTF-8def stringTest():    # Python中的字符串是不可变的，同Java一样，所以下面创建了三个字符串对象    msg = "Hello" + " world!"    print("string concat: " + msg)    # 可以通过索引方式访问字符串中的单个字符    print("string access by index: " + msg[1])    # 字符串长度函数，len    print("string len function: lengh of hello is " + str(len("hello")))    # 字符串不能直接与数字进行 + 运算（即不支持隐式转换数字类型到字符串类型），必须通过str函数将数字转成字符串    # print(msg + 3.14) # wrong    print("str function: " + (msg + str(3.14)))    # 布尔类型也如此    # print(msg + True)    # 但是可以这样进行普通字符串与数字或布尔值拼接，但是注意拼接得到的两个字符串之间会有一个空格    print(msg, 3.14) # Hello world! 3.14    print(msg, True) # Hello world! True    # raw字符串，不进行转义处理    rawStr = r"this\n\r\t is a good habit"    print("raw string: " + rawStr)    # 跨行字符串    multiLineStr = """It's the best timeIt's the worst time"""    print("multiline string: " + multiLineStr)    # 字符串相关函数    # s.lower()、s.upper()    print("string lower function: " + "hello".upper())    print("string upper function: " + "WORLD".lower())    # s.strip()移除首尾空格（包括\r\t...）    print("string strip function: " +  " hello world \t".strip())    # s.isalpha()    print("a".isalpha())    # s.isdigit()    print("314".isdigit())  # True    print("3.14".isdigit()) # False    print("314".isnumeric())    print("abc314".isalnum()) # True    # 其他的还有islower() isupper() isspace()    # ...    # s.startswith(other) s.endswith(other)    print("hello".startswith("h"))    print("world".endswith("d"))     # s.find(other)，以other的第一个字符为准进行查找，如果找到返回这个字符在s中的索引，否则返回-1    print("string find function: o locate at index " + str("hello".find("o")))    print("o" in "hello")    # s.replace(old, new)    print("string replace function: " + "hello".replace("ello", "appy"))    # s.split(delimeter) 获得字符串列表    print("string split function: " + str("hello world".split(" ")))    # s.join(list) 将字符串列表中的元素用字符串s连起来    print("string join function: " + "###".join(["hello", "world"]))    # 字符串切片slice    # hello 从左到右的index为 0 1 2 3 4，而从右到左的index为-1 -2 -3 -4 -5。即0对应-5...4对应-1    print("string slice function: " + "hello"[1:3]) # 从index为1的字符开始切，切3-1=2个字符    print("string slice function: " + "hello"[1:5])     print("string slice function: " + "hello"[1:6])    print("string slice function: " + "hello"[2:])    print("string slice function: " + "hello"[:3])    print("string slice function: " + "hello"[:])   # 字符串复制    print("string slice function: " + "hello"[-1])    print("string slice function: " + "hello"[:-3]) # 不包括最后3个字符    print("string slice function: " + "hello"[-3:]) # 从倒数第三个字符开始至最后一个字符    print("string slice function: " + "hello"[0:-2]) # hel    print("string slice function: " + "hello"[-1:0]) # 空字符串    print("string slice function: " + "hello"[-1:1]) # 空字符串    print("string slice function: " + "hello"[-2:2]) # 空字符串    print("string slice function: " + "hello"[-5:-1])# hell    # 注意除了字符串外，其他列表类型也支持切片    # 字符串格式化 %的应用    text = "%d fox jumps over the %s" % (1, "fence")    print("string format by %: " + text)    # 跨行    text = ("%d pigs walk towards the %s"            % (2, "wall"))    print("string format by % corss line: " + text)    # unicode字符串    # Python 3中所有的字符串都是Unicode字符串    # 而Python 3之前可以这样声明一个Unicode字符串 s = u"unicode string"    # bytes类型对象    bso = b"bytes object+"    print("bytes object: " + str(bso))    print("bytes object concat: " + str(bso + b" 2"))    print("bytes object length: " + str(len(bso)))    # bytes类型对象只能包含ASCII字符，不能包含中文    # bso = b"bytes object+中文" # 运行时报错“SyntaxError: bytes can only contain ASCII literal characters.”    # bytearray类型对象    bao = bytearray(bso)    print(str(bao)) # bytearray(b'bytes object+')    # 索引方式操纵字节    bao[0] = 99    print(str(bao))    # 字符串编码解码    myStr = "Python编程"    print("myStr original length: " + str(len(myStr)))    utf8EncodedStr = myStr.encode("utf-8")    print(utf8EncodedStr, len(utf8EncodedStr))    gb18030EncodedStr = myStr.encode("gb18030")    print(gb18030EncodedStr, len(gb18030EncodedStr))    # utf8解码    utf8DecodedStr = utf8EncodedStr.decode("utf-8")    print(utf8DecodedStr)    # Python 3支持的编码方式见：http://docs.python.org/2/library/codecs.html#standard-encodingsdef main():    stringTest()if __name__ == '__main__':    main()