如何确保我的正则表达式不会匹配太多
文件中的单词很少，且开头带有数字。我想提取特定的 no 行。当给定 1 时，它也会提取第 1 行以及 11, 21
FILE.txt 的内容：
1.sample lines of 2.sentences present in ... ... 10.the 11.file
当执行时 pro 1 file.txt 给出第 1,10 行和第 11 行的结果 因为这三个结果的字符串中有 1。即
脚本的输出：
1.sample 10.the 11.file
预期输出：我期望的输出 仅是第 1 行内容，而不是第 10 行或第 11 行内容。 即
预期输出：
1.sample
我当前的代码：
proc pro { pattern args} {
set file [open $args r]
set lnum 0
set occ 0
while {[gets $file line] >=0} {
incr lnum
if {[regexp $pattern $line]} {
incr occ
puts "The pattern is present in line: $lnum"
puts "$line"
} else {
puts "not found"
}
}
puts "total number of occurencese : $occ"
close $file
}
程序工作正常，但问题是我正在检索我不希望与预期行一起检索的行。由于我想要检索的数字 (1) 存在于其他字符串中，例如 11、21、14 等，这些行也会被打印。
请容忍我解释问题的不清楚方式。
A file has few words with numbers in the begining of them. i want to extract a particular no line.when given 1, it extracts line 1 also with 11, 21
FILE.txt has contents:
1.sample lines of 2.sentences present in ... ... 10.the 11.file
when Executed pro 1 file.txt
gives results from line 1,10 and also from line 11
as these three results have 1 in their string. i.e
Output of the script:
1.sample 10.the 11.file
Expected output: the output which i am expecting
is only line 1 contents and not the line 10 or line 11 contents.
i.e
Expected output:
1.sample
My current code:
proc pro { pattern args} {
set file [open $args r]
set lnum 0
set occ 0
while {[gets $file line] >=0} {
incr lnum
if {[regexp $pattern $line]} {
incr occ
puts "The pattern is present in line: $lnum"
puts "$line"
} else {
puts "not found"
}
}
puts "total number of occurencese : $occ"
close $file
}
the program is working fine but the thing is i am retrieving lines that i dont want to along with the expected line. As the number (1) which i want to retrieve is present in the other strings such as 11, 21, 14 etc these lines are also getting printed.
kindly tolerate my unclear way of explaining the question.
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评论（3）
您可以按照 glen 建议使用单词边界来解决问题，但您还可以考虑以下事项：
如果每个行号后面都有一个
.那么您可以将其用作正则表达式中的分隔符我也会建议使用
^（在行开头匹配），这样即使数字出现在该行其他地方，也不会被计算在内。tcl 单词边界在 http://www.regular-expressions.info/wordboundaries.html< /a>
You can solve the problem using word boundaries as suggested by glen but you can also consider the following things:
If after every line number there is a
.then you can use it as delimiter in regular expressionI would also suggest to use
^(match at the beginning of line) so that even if number is present in the line elsewhere it would not get counted.tcl word boundaries are well explained at http://www.regular-expressions.info/wordboundaries.html
您必须确保您的模式仅在单词边界之间匹配：
请参阅 正则表达式语法。
You have to ensure your pattern matches only between word boundaries:
See the documentation for regular expression syntax.
如果您想要做的事情与您所描述的一样受到限制，为什么不直接使用类似的东西
If what you're looking to do is as constrained as what you're describing, why not just use something like