Python 字符串

除了数字，Python也能操作字符串。字符串有几种表达方式，可以使用单引号或双引号括起来：

>>> 'spam eggs''spam eggs'>>> 'doesn't'"doesn't">>> "doesn't""doesn't">>> '"Yes," he said.''"Yes," he said.'>>> ""Yes," he said."'"Yes," he said.'>>> '"Isn't," she said.''"Isn't," she said.'

Python中使用反斜杠转义引号和其它特殊字符来准确地表示。

如果字符串包含有单引号但不含双引号，则字符串会用双引号括起来，否则用单引号括起来。对于这样的输入字符串，print() 函数会产生更易读的输出。

跨行的字面字符串可用以下几种方法表示。使用续行符，即在每行最后一个字符后使用反斜线来说明下一行是上一行逻辑上的延续：

以下使用 来添加新行：

>>> '"Isn't," she said.''"Isn't," she said.'>>> print('"Isn't," she said.')"Isn't," she said.>>> s = 'First line.Second line.' #  意味着新行>>> s # 不使用 print(),  包含在输出中'First line.Second line.'>>> print(s) # 使用 print(),  输出一个新行First line.Second line.

以下使用 反斜线() 来续行：

hello = "This is a rather long string containingseveral lines of text just as you would do in C. Note that whitespace at the beginning of the line is significant."print(hello)

注意，其中的换行符仍然要使用 表示——反斜杠后的换行符被丢弃了。以上例子将如下输出：

This is a rather long string containingseveral lines of text just as you would do in C. Note that whitespace at the beginning of the line is significant.

或者，字符串可以被 """ (三个双引号)或者 ''' (三个单引号)括起来。使用三引号时，换行符不需要转义，它们会包含在字符串中。以下的例子使用了一个转义符，避免在最开始产生一个不需要的空行。

print("""甥慳敧: thingy [OPTIONS] -h Display this usage message -H hostname Hostname to connect to""")

其输出如下：

Usage: thingy [OPTIONS] -h Display this usage message -H hostname Hostname to connect to

如果我们使用"原始"字符串，那么 不会被转换成换行，行末的的反斜杠，以及源码中的换行符，都将作为数据包含在字符串内。例如：

hello = r"This is a rather long string containingseveral lines of text much as you would do in C."print(hello)

将会输出：

This is a rather long string containingseveral lines of text much as you would do in C.

字符串可以使用 + 运算符串连接在一起，或者用 * 运算符重复：

>>> word = 'Help' + 'A'>>> word'HelpA'>>> ''''

两个紧邻的字面字符串将自动被串连；上例的第一行也可以写成 word = 'Help' 'A' ；这样的操作只在两个字面值间有效，不能随意用于字符串表达式中：

>>> 'str' 'ing' # >> 'str'.strip() + 'ing' # >> 'str'.strip() 'ing' #