Python：怎樣拼裝超長字符串和包含回車換行字符串

最近更新時間 2020-11-28 12:58:10

Python 中字符串可以使用單引號（'……'）或雙引號（"……"）表示。反斜槓 \ 是轉義字符。如果你不希望 \ 轉義字符成特殊字符，可以在引號前添加 r 即可。如下所示：

"first_name"
# Output: first_name

'\'last_name\''
# Output: 'last_name'


# 沒有特殊字符
path = r'd:\some\name'
# Output: d:\some\name

如果字符串很長，包括回車和換行用 ' 或 " 已經不能很好的表示。可以使用三重引號："""...""" 或 '''...'''。字符串中的回車換行會自動包含到字符串中，如果不想包含，在行尾添加一個 \ 即可。如下所示:

table = """\
CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL AUTO_INCREMENT,"
  `birth_date` date NOT NULL,"
  `first_name` varchar(14) NOT NULL,"
  `last_name` varchar(16) NOT NULL,"
  `gender` enum('M','F') NOT NULL,"
  `hire_date` date NOT NULL,"
  PRIMARY KEY (`emp_no`)"
) ENGINE=InnoDB
"""

CREATE TABLE `employees` (
  `emp_no` int(11) NOT NULL AUTO_INCREMENT,"
  `birth_date` date NOT NULL,"
  `first_name` varchar(14) NOT NULL,"
  `last_name` varchar(16) NOT NULL,"
  `gender` enum('M','F') NOT NULL,"
  `hire_date` date NOT NULL,"
  PRIMARY KEY (`emp_no`)"
) ENGINE=InnoDB

相鄰兩個或多個字符串將會自動連接到一起，該特性對很長的字符串拆開顯示非常有用。如下所示:

text = (
    "CREATE TABLE `salaries` ("
    "  `emp_no` int(11) NOT NULL,"
    "  `salary` int(11) NOT NULL,"
    "  `from_date` date NOT NULL,"
    "  `to_date` date NOT NULL,"
    "  PRIMARY KEY (`emp_no`,`from_date`), KEY `emp_no` (`emp_no`),"
    "  CONSTRAINT `salaries_ibfk_1` FOREIGN KEY (`emp_no`) "
    "     REFERENCES `employees` (`emp_no`) ON DELETE CASCADE"
    ") ENGINE=InnoDB")

CREATE TABLE `salaries` (  `emp_no` int(11) NOT NULL,  `salary` int(11) NOT NULL,  `from_date` date NOT NULL,  `to_date` date NOT NULL,  PRIMARY KEY (`emp_no`,`from_date`), KEY `emp_no` (`emp_no`),  CONSTRAINT `salaries_ibfk_1` FOREIGN KEY (`emp_no`)      REFERENCES `employees` (`emp_no`) ON DELETE CASCADE) ENGINE=InnoDB

與三重引號相比，合併後的字符串不會有換行回車，對執行拼裝執行命令的字符串更有用。

Python：怎樣拼裝超長字符串和包含回車換行字符串

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