Well, regular expressions have been something that I was scared of when I started coding as a serious stuff. The string literals puzzled me like anything. preg_match, preg_grep, preg_split, preg_replace etc have been something I always wanted to avoid. But thanks to phpbuilder and php that I can now handle them with some ease. And this is for you guys who find regular expressions tacky.
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VERY BASICS:
1. “^tech“
Searches a string that starts with tech.
2. “logy$”
Searches for strings that ends up in logy.
3. “a*b”
Looks for a string that has either zero or more a’s but exactly one b following a. (eg. b, ab, aab, aaab, aaaaaaaaaaaaaaaaab etc.).
4. “a+b”
Same as a*b but only difference is that atleast one a should be there in the string unlike a*b which can overlook a. (eg. ab, aab,aaaaaaaaab etc).
5. “a?b”
In this case string might have either zero or a single a (eg. ab or b) only these two possibilities are there.
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QUANTIFYING THE CHARACTERS:
To quantify the characters into certain sets and utilize them we can use paranthesis().
6. “(abc)+def”
Matches a string which consists of pattern having abc either one or n times followed by def at the end.
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LOGICAL OPERATORS [OR(|) & AND(.)]:
7. “(a|b)*c”
A string of a and b that ends in a c.
To specify range of characters. For instance to match that in a password small-case character, you can specify the set as [a-z] or [A-Z] or [0-9].
8. “([a-z])|([A-Z])”
Searches for a pattern having either small-case or capital letters.
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That’s all
Cheers!!