如何在Perl中创建仅匹配数字和小数点分隔符的正则表达式

Question

I want to have a regex that reject string that contain any alphabets. But allow numbers like: 4, 4.5, 12.330 but not 12.2.3.4 (multiple dots).

But why this regex of mine failed?

my $str1 = $ARGV[0] || "foo1";


if ($str1 =~ /^[\d+]|[^a-zA-Z]+|[\.]\d+$/) {
  print "This is strictly numeric: $str1\n";
}
else {
   print "This contain alphabet\n";
}

The input still pass first condition which I don't want.

Running example here: https://eval.in/73654

Answer 1

if ($str1 =~ /^\d+(?:\.\d+)?$/) { ... }

如果您还希望以小数点分隔符结尾且没有后跟数字的字符串，请使用

if ($str1 =~ /^\d+(?:\.\d*)?$/) { ... }

Answer 2

I think you need parens around your ors:

if ( $str1 =~ /^([\d+]|[^a-zA-Z]+|[\.]\d+)$/ ) {

also

[^a-zA-Z]+ will match everything that \\d+ or \\.\\d+ would.

also

you could write the first and last terms as simply \\.?\\d+

but really, that's not what you want since you also want 4.5 which would match against something like \\d+\\.?\\d*