Those two conditions create 3 valid situations. The 3 valid situations of a key-value pair There is a key and the value which is not undef then both the exists and defined functions will return true. There is a key and the value is undef then exists will return true and defined will return false.
If there is no such key, then there cannot be a corresponding values. In that case both exists and defined will return false. The key Qux exists but its values is NOT defined. You may also have a look at the following articles to learn more —. Submit Next Question. By signing up, you agree to our Terms of Use and Privacy Policy. Forgot Password?
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Perl file exists By Abhilasha Chougule. Popular Course in this category. Active 3 years, 6 months ago. Viewed 32k times. Improve this question. Jean Jean Add a comment. Active Oldest Votes. Improve this answer. But I am unable to put regexp in there.
Can I use regular expressions? Jean You can grep after the glob, e. Show 1 more comment. Matthew Lock Matthew Lock Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. By Kirk Brown Kirk Brown. Learn about our Editorial Process.
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