如何在 lex 中识别扫描仪的字符串文字？

发布于 2024-10-23 20:57:22 字数 263 浏览 1 评论 0原文

好吧，我一直在尝试在 lex 中找到一个正则表达式，它可以识别输入字符串中类似 C 的字符串文字。例如。在 printf("stackoverflow") 中，“stackoverflow”应被识别为字符串文字。我一直在尝试以下方法：

"[.]+"
["][.]+["]
\"[.]+\"
[\"][.]+[\"]
"""[.]+"""

这些都不起作用。每次识别的词位都是“alone”，我该怎么办？提前致谢...

原文

Ok, I have been trying to find a regular expression in lex that will recognize a C-like string literal in an input string. eg. in printf("stackoverflow"), "stackoverflow" should be recognized as a string literal.
I have been trying the following:

"[.]+"
["][.]+["]
\"[.]+\"
[\"][.]+[\"]
"""[.]+"""

None of these is working. The lexeme recognized each time is " alone. What should I do?
Thanks in advance...

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花海 2024-10-30 20:57:23

很简单，试试这个：

\".*\"     printf("STRING[%s]", yytext);
\'.*\'     printf("STRING[%s]", yytext);

编译和运行时，快速测试显示它正确解析字符串，例如

"hello world!"
STRING["hello world!"]
'hello world!'
STRING['hello world!']
'john\'s cat'
STRING['john\'s cat']
'mary said "hello!"'
STRING['mary said "hello!"']
"frank said \"goodbye!\""
these are words "which contain" a string
these are words STRING["which contain"] a string

Simple, try this:

\".*\"     printf("STRING[%s]", yytext);
\'.*\'     printf("STRING[%s]", yytext);

When compiled and run, a quick test shows it correctly parses strings like

"hello world!"
STRING["hello world!"]
'hello world!'
STRING['hello world!']
'john\'s cat'
STRING['john\'s cat']
'mary said "hello!"'
STRING['mary said "hello!"']
"frank said \"goodbye!\""
these are words "which contain" a string
these are words STRING["which contain"] a string

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