This is a homework assignment and my first experience using RegEx. I am starting to grasp the syntax and symbols used and can do some simple pattern matching/manipulation, but can't quite foresee how to achieve some of the goals of this assignment.
I have been given a text file that is formatted like this:
Steve Blenheim:238-923-7366:95 Latham Lane, Easton, PA 83755:11/12/56:20300
Betty Boop:245-836-8357:635 Cutesy Lane, Hollywood, CA 91464:6/23/23:14500
Igor Chevsky:385-375-8395:3567 Populus Place, Caldwell, NJ 23875:6/18/68:23400
Norma Corder:397-857-2735:74 Pine Street, Dearborn, MI 23874:3/28/45:245700
There are about 50 lines of names and corresponding info, each entry is on a new line and each 'field' is separated by a colon. Mostly I need to find specific things from the file and print them on a webpage but I don't quite understand.
Here is one problem I solved:
$myFile = "datebook.txt";
$data = file($myFile);//I have used this to place all data in an array, but it may be necessary to place the data into a string?
//1) Print all lines containing the pattern Street (case insensitive).
$pattern = "/street/i";
$linesFound = preg_grep($pattern, $data);
echo "<pre>", print_r($linesFound, true), "</pre>";
Here are some I have not and specific questions regarding them:
2) Print the first and last names in which the first name starts with a letter ‘B’.
How do I only search for first names and not last names, city names, etc?
How do I print the full name and only the full name?
5) Print Lori Gortz’s name and address.
I understand how to find the pattern 'Lori Gortz' but how do I return her address as well?
11) Print lines that end in exactly five digits.
12) Print the file with the first and last names reversed.
14) Give everyone a $250.00 raise.
Don't know how to do any of these. I assume the last number for each entry is their salary.
Any help is appreciated. Please respond with an explanation of the code as well, thank you.
Check the RegEx quick reference, I think you'll figure out most of your tasks there. For example, Lori's address would be a string after the number after the second colon and before the second coma (in her line, of course).
The best way to do all the task would be to go over each line and make an array with all the elements. That way you could easy replace names, increase salaries, check if it ends with 5 digits, etc.
You can also try this online tester. Good luck.
Edit:
Little help for a start:
^[A-z ]* this gets full names
^[A-z]* this gets first names
etc...
Edit2:
See what this code does:
$line = "Betty Boop:245-836-8357:635 Cutesy Lane, Hollywood, CA 91464:6/23/23:14500";
$regex = "/\s|:/";
$result = preg_split($regex, $line);
:)
I don't want to do all of them, but here's some hints.. For question 2:
^[A-Z]* B.*$
^ basically means a new line.
[A-Z]* means any number of characters from A-Z
Next we match a space
Next we match a B
The .* means any number of other characters.
Lastly, we match with an end of line using $
This can definitely be improved and made more flexible, but I'll let you do that..
Related
I'm currently looking to implement a search function on my website.
I have it working with 1 word/name, but I can't seem to figure out how to split and identify certain parts of the search string.
Example:
I have a user in my database with the name "Steve de Vette"
(My country has words in between almost all of the first and last names but not always, and sometimes more than one. ex: "Kees van der Berg") But his name is of course split up in multiple parts. "vNaam", "Tvoegsel"(meaning the "de" or "van der") and "aNaam".
This complicates things a bit for me, since I now have to split the search string, which on it's own isn't a big deal. But I need to know how I can get the correct results every time.
So I guess it comes down to this: How can I make it so that the name is split up like it should, or maybe there's a way to strip these thing all together, but for the likes of me I can't seem to figure it out.
Any help would be greatly appreciated!
EDIT:
I have tried just exploding the name and searching with multiple OR_LIKE clauses. This works until I have no "tussenvoegsel" and one of the Like statements reads "OR anaam LIKE '%%'"
split the string with explode and search for the first and last item.
$string1 = "Steve de Vette";
$string2 = "Kees van der Berg";
$ex1 = explode(" ", $string2);
$nr = count($ex1);
echo $ex1[0]; //firstname
echo ' ';
echo $ex1[$nr-1]; //lastname
Well you can use the PHP string searching funciton.
$pos = strpos($string, $character);
You could use this to find the first space in the name. So if you take "Steve de Vette", you could first find Steve as the first name, then the rest of the string you could search again or keep the rest of it as the last name.
This is a snippet of code taken from my own site.
$fname = strstr($entry," ",true); <-- finds the first name (all characters up to the first space)
$len = strlen($fname) + 1; <-- skips over the space to the last name
$entrylen = strlen($entry); <-- gets the length of the search string used
$sname = substr($entry, $len, $entrylen); <-- gets the rest of the string (last name)
Hope you find this helpful
What i do is strip out any spaces all together. I store spaces in my database like normal but use the replace feature when searching to strip out spaces. then strip out spaces from the search field as well and use the like with the wild card on the right hand side. I try to make the search as simple as possible. searching with one word seems to work better all together so forcing one word seems to be the thing that works for me.
I try to create a regular expression with searches in a huge document for a persons full name. In the text the name can be written in full, or the first names can be either abbreviated to a single letter or a letter followed by a dot or omitted. For instance my search for _ALBERTO JORGE ALONSO CALEFACCION_now is:
preg_match('/([;:.,&\s\xc2\-(){}!"'<>]{1})(ALBERTO|A.|A)[\s\xc2-]+
(JORGE|J.|J)?[\s\xc2,]+(ALONSO)[\s\xc2*-]+(CALEFACCION))([;:.,&\s\xc2(){}
!"'<>]{1})/i', $text, $match);
Between the first names and last names an asterisk (*) can be present.
This is working for the case all first names are at least present some way. But I don't know to extend the expression when first names are omitted. Can you help me?
Let's start by simplifying what you have;
start:
/([;:.,&\s\xc2\-(){}!"'<>]{1})(ALBERTO|A.|A)[\s\xc2-]+(JORGE|J.|J)?[\s\xc2,]+(ALONSO)[\s\xc2*-]+(CALEFACCION)([;:.,&\s\xc2(){}!"'<>]{1})/i
as I said in my comment, \b is "word break", so you can simplify a lot of that:
/\b(ALBERTO|A.|A)[\s\xc2-]+(JORGE|J.|J)?[\s\xc2,]+(ALONSO)[\s\xc2*-]+(CALEFACCION)\b/i
(added bonus: it won't match the characters either side now, and it will match at the start and end of the text)
Next, you can use the ? token for the dots (which should be escaped by the way; . is special and means "match anything")
/\b(ALBERTO|A\.?)[\s\xc2-]+(JORGE|J\.?)?[\s\xc2,]+(ALONSO)[\s\xc2*-]+(CALEFACCION)\b/i
Finally, to actually answer your question, you have 2 choices. Either make the entire bracketed name optional, or add a new blank option. The first is the most flexible, since we'll need to cope with the whitespace too:
/\b((ALBERTO|A\.?)[\s\xc2-]+((JORGE|J\.?)[\s\xc2,]+)?)?(ALONSO)[\s\xc2*-]+(CALEFACCION)\b/i
Note that if you're reading the matched parts you'll need to update your indices. Also note that this fixed an issue where omitting the second name (JORGE) still required an extra space.
This will match things like A. J. ALONSO CALEFACCION, A. ALONSO CALEFACCION and ALONSO CALEFACCION, but not J. ALONSO CALEFACCION (it's only a small tweak if you do want that)
Breaking up that final string for clarity:
/\b
(
(ALBERTO|A\.?)[\s\xc2-]+
(
(JORGE|J\.?)[\s\xc2,]+
)?
)?
(ALONSO)[\s\xc2*-]+
(CALEFACCION)
\b/i
Finally, it's an odd thought, but you could change the names which can be initials to be in this form: (A(LBERTO|\.|)), which means you're not repeating the initials (a potential source of mistakes)
So I've been working on a little project to write a syntax highlighter for a game's scripting language. It's all gone off without a hitch, except for one part: the numbers.
Take these lines for example
(5:42) Set database entry {healthpoints2} to the value 100.
(5:140) Move the user to position (29,40) on the map.
I want to highlight that 100 on the end, without highlighting the (5:42) or the 2 in the braces. The numbers won't always be in the same place, and there won't always only be one number.
I basically need a regexp to say:
"Match any numbers that aren't anywhere between {} and don't match the (#:#) pattern."
I've been at this for a day and a half now and I'm pulling out my hair trying to figure it out. Help with this would be greatly appreciated!
I've already looked at regular-expressions.info, and tried playing around with RegexBuddy, but i'm just not getting it :c
Edit: By request, here's some more lines copied right from the script editor.
(0:7) When somebody moves into position (**10** fhejwkfhwjekf **20**,
(0:20) When somebody rolls exactly **10** on **2** dice of **6** sides,
(0:31) When somebody says {...},
(3:3) within the diamond (**5**,**10**) - **20** //// **25**,
(3:14) in a line starting at (#, #) and going # more spaces northeast.
(5:10) play sound # to everyone who can see (#,#).
(5:14) move the user to (#,#) if there's nobody already there.
(5:272) set message ~msg to be the portion of message ~msg from position # to position #.
(5:302) take variable %var and add # to it.
(5:600) set database entry {...} about the user to #.
(5:601) set database entry {...} about the user named {...} to #.
You might kick yourself when you see this solution...
Assuming this desired number will always be used in a sentence, it should always have a space preceding it.
$pattern = '/ [0-9]+/s';
If the preceding space isn't always present, let me know and I'll update the answer.
Here's the updated regex to match the 2 examples in your question:
$pattern = '/[^:{}0-9]([0-9,]+)[^:{}0-9]/s';
3nd update to account for your question revisions:
$pattern = '/[^:{}0-9a-z#]([0-9]+[, ]?[0-9]*)[^:{}0-9a-z#]/s';
So you don't highlight the number in things like
{update 29 testing}
you might want to pre strip the braces, like so:
$pattern = '/[^:{}0-9a-z#]([0-9]+[, ]?[0-9]*)[^:{}0-9a-z#]/s';
$str = '(0:7) Hello {update 29 testing} 123 Rodger alpha charlie 99';
$tmp_str = preg_replace('/{[^}]+}/s', '', $str);
preg_match($pattern, $tmp_str, $matches);
(\d+,\s?\d+)|(?<![\(\{:]|:\d)\d+(?![\)\}])
http://regexr.com?30omd
Would this work?
I'm just getting to know regular expressions, but after doing quite a bit of reading (and learning quite a lot), I still have not been able to figure out a good solution to this problem.
Let me be clear, I understand that this particular problem might be better solved not using regular expressions, but for the sake of brevity let me just say that I need to use regular expressions (trust me, I know there are better ways to solve this).
Here's the problem. I'm given a big file, each line of which is exactly 4 characters long.
This is a regex that defines "valid" lines:
"/^[AB][CD][EF][GH]$/m"
In english, each line has either A or B at position 0, either C or D at position 1, either E or F at position 2, and either G or H at position 3. I can assume that each line will be exactly 4 characters long.
What I'm trying to do is given one of those lines, match all other lines that contain 2 or more common characters.
The below example assumes the following:
$line is always a valid format
BigFileOfLines.txt contains only valid lines
Example:
// Matches all other lines in string that share 2 or more characters in common
// with "$line"
function findMatchingLines($line, $subject) {
$regex = "magic regex I'm looking for here";
$matchingLines = array();
preg_match_all($regex, $subject, $matchingLines);
return $matchingLines;
}
// Example Usage
$fileContents = file_get_contents("BigFileOfLines.txt");
$matchingLines = findMatchingLines("ACFG", $fileContents);
/*
* Desired return value (Note: this is an example set, there
* could be more or less than this)
*
* BCEG
* ADFG
* BCFG
* BDFG
*/
One way I know that will work is to have a regex like the following (the following regex would only work for "ACFG":
"/^(?:AC.{2}|.CF.|.{2}FG|A.F.|A.{2}G|.C.G)$/m"
This works alright, performance is acceptable. What bothers me about it though is that I have to generate this based off of $line, where I'd rather have it be ignorant of what the specific parameter is. Also, this solution doesn't scale terrible well if later the code is modified to match say, 3 or more characters, or if the size of each line grows from 4 to 16.
It just feels like there's something remarkably simple that I'm overlooking. Also seems like this could be a duplicate question, but none of the other questions I've looked at really seem to address this particular problem.
Thanks in advance!
Update:
It seems that the norm with Regex answers is for SO users to simply post a regular expression and say "This should work for you."
I think that's kind of a halfway answer. I really want to understand the regular expression, so if you can include in your answer a thorough (within reason) explanation of why that regular expression:
A. Works
B. Is the most efficient (I feel there are a sufficient number of assumptions that can be made about the subject string that a fair amount of optimization can be done).
Of course, if you give an answer that works, and nobody else posts the answer *with* a solution, I'll mark it as the answer :)
Update 2:
Thank you all for the great responses, a lot of helpful information, and a lot of you had valid solutions. I chose the answer I did because after running performance tests, it was the best solution, averaging equal runtimes with the other solutions.
The reasons I favor this answer:
The regular expression given provides excellent scalability for longer lines
The regular expression looks a lot cleaner, and is easier for mere mortals such as myself to interpret.
However, a lot of credit goes to the below answers as well for being very thorough in explaining why their solution is the best. If you've come across this question because it's something you're trying to figure out, please give them all a read, helped me tremendously.
Why don't you just use this regex $regex = "/.*[$line].*[$line].*/m";?
For your example, that translates to $regex = "/.*[ACFG].*[ACFG].*/m";
This is a regex that defines "valid" lines:
/^[A|B]{1}|[C|D]{1}|[E|F]{1}|[G|H]{1}$/m
In english, each line has either A or B at position 0, either C or D
at position 1, either E or F at position 2, and either G or H at
position 3. I can assume that each line will be exactly 4 characters
long.
That's not what that regex means. That regex means that each line has either A or B or a pipe at position 0, C or D or a pipe at position 1, etc; [A|B] means "either 'A' or '|' or 'B'". The '|' only means 'or' outside of character classes.
Also, {1} is a no-op; lacking any quantifier, everything has to appear exactly once. So a correct regex for the above English is this:
/^[AB][CD][EF][GH]$/
or, alternatively:
/^(A|B)(C|D)(E|F)(G|H)$/
That second one has the side effect of capturing the letter in each position, so that the first captured group will tell you whether the first character was A or B, and so on. If you don't want the capturing, you can use non-capture grouping:
/^(?:A|B)(?:C|D)(?:E|F)(?:G|H)$/
But the character-class version is by far the usual way of writing this.
As to your problem, it is ill-suited to regular expressions; by the time you deconstruct the string, stick it back together in the appropriate regex syntax, compile the regex, and do the test, you would probably have been much better off just doing a character-by-character comparison.
I would rewrite your "ACFG" regex thus: /^(?:AC|A.F|A..G|.CF|.C.G|..FG)$/, but that's just appearance; I can't think of a better solution using regex. (Although as Mike Ryan indicated, it would be better still as /^(?:A(?:C|.E|..G))|(?:.C(?:E|.G))|(?:..EG)$/ - but that's still the same solution, just in a more efficiently-processed form.)
You've already answered how to do it with a regex, and noted its shortcomings and inability to scale, so I don't think there's any need to flog the dead horse. Instead, here's a way that'll work without the need for a regex:
function findMatchingLines($line) {
static $file = null;
if( !$file) $file = file("BigFileOfLines.txt");
$search = str_split($line);
foreach($file as $l) {
$test = str_split($l);
$matches = count(array_intersect($search,$test));
if( $matches > 2) // define number of matches required here - optionally make it an argument
return true;
}
// no matches
return false;
}
There are 6 possibilities that at least two characters match out of 4: MM.., M.M., M..M, .MM., .M.M, and ..MM ("M" meaning a match and "." meaning a non-match).
So, you need only to convert your input into a regex that matches any of those possibilities. For an input of ACFG, you would use this:
"/^(AC..|A.F.|A..G|.CF.|.C.G|..FG)$/m"
This, of course, is the conclusion you're already at--so good so far.
The key issue is that Regex isn't a language for comparing two strings, it's a language for comparing a string to a pattern. Thus, either your comparison string must be part of the pattern (which you've already found), or it must be part of the input. The latter method would allow you to use a general-purpose match, but does require you to mangle your input.
function findMatchingLines($line, $subject) {
$regex = "/(?<=^([AB])([CD])([EF])([GH])[.\n]+)"
+ "(\1\2..|\1.\3.|\1..\4|.\2\3.|.\2.\4|..\3\4)/m";
$matchingLines = array();
preg_match_all($regex, $line + "\n" + $subject, $matchingLines);
return $matchingLines;
}
What this function does is pre-pend your input string with the line you want to match against, then uses a pattern that compares each line after the first line (that's the + after [.\n] working) back to the first line's 4 characters.
If you also want to validate those matching lines against the "rules", just replace the . in each pattern to the appropriate character class (\1\2[EF][GH], etc.).
People may be confused by your first regex. You give:
"/^[A|B]{1}|[C|D]{1}|[E|F]{1}|[G|H]{1}$/m"
And then say:
In english, each line has either A or B at position 0, either C or D at position 1, either E or F at position 2, and either G or H at position 3. I can assume that each line will be exactly 4 characters long.
But that's not what that regex means at all.
This is because the | operator has the highest precedence here. So, what that regex really says, in English, is: Either A or | or B in the first position, OR C or | or D in the first position, OR E or | or F in the first position, OR G or '|orH` in the first position.
This is because [A|B] means a character class with one of the three given characters (including the |. And because {1} means one character (it is also completely superfluous and could be dropped), and because the outer | alternate between everything around it. In my English expression above each capitalized OR stands for one of your alternating |'s. (And I started counting positions at 1, not 0 -- I didn't feel like typing the 0th position.)
To get your English description as a regex, you would want:
/^[AB][CD][EF][GH]$/
The regex will go through and check the first position for A or B (in the character class), then check C or D in the next position, etc.
--
EDIT:
You want to test for only two of these four characters matching.
Very Strictly speaking, and picking up from #Mark Reed's answer, the fastest regex (after it's been parsed) is likely to be:
/^(A(C|.E|..G))|(.C(E)|(.G))|(..EG)$/
as compared to:
/^(AC|A.E|A..G|.CE|.C.G|..EG)$/
This is because of how the regex implementation steps through text. You first test if A is in the first position. If that succeeds, then you test the sub-cases. If that fails, then you're done with all those possible cases (or which there are 3). If you don't yet have a match, you then test if C is in the 2nd position. If that succeeds, then you test for the two subcases. And if none of those succeed, you test, `EG in the 3rd and 4th positions.
This regex is specifically created to fail as fast as possible. Listing each case out separately, means to fail, you would have test 6 different cases (each of the six alternatives), instead of 3 cases (at a minimum). And in cases of A not being the first position, you would immediately go to test the 2nd position, without hitting it two more times. Etc.
(Note that I don't know exactly how PHP compiles regex's -- it's possible that they compile to the same internal representation, though I suspect not.)
--
EDIT: On additional point. Fastest regex is a somewhat ambiguous term. Fastest to fail? Fastest to succeed? And given what possible range of sample data of succeeding and failing rows? All of these would have to be clarified to really determine what criteria you mean by fastest.
Here's something that uses Levenshtein distance instead of regex and should be extensible enough for your requirements:
$lines = array_map('rtrim', file('file.txt')); // load file into array removing \n
$common = 2; // number of common characters required
$match = 'ACFG'; // string to match
$matchingLines = array_filter($lines, function ($line) use ($common, $match) {
// error checking here if necessary - $line and $match must be same length
return (levenshtein($line, $match) <= (strlen($line) - $common));
});
var_dump($matchingLines);
I bookmarked the question yesterday in the evening to post an answer today, but seems that I'm a little late ^^ Here is my solution anyways:
/^[^ACFG]*+(?:[ACFG][^ACFG]*+){2}$/m
It looks for two occurrences of one of the ACFG characters surrounded by any other characters. The loop is unrolled and uses possessive quantifiers, to improve performance a bit.
Can be generated using:
function getRegexMatchingNCharactersOfLine($line, $num) {
return "/^[^$line]*+(?:[$line][^$line]*+){$num}$/m";
}
I'm looking for the best reliable way to return the first and last name of a person given the full name, so far the best I could think of is the following regular expression:
$name = preg_replace('~\b(\p{L}+)\b.+\b(\p{L}+)\b~i', '$1 $2', $name);
The expected output should be something like this:
William -> William // Regex Fails
William Henry -> William Henry
William Henry Gates -> William Gates
I also want it to support accents, for instance "João".
EDIT: I understand that some names will not be properly identified, but this isn't a problem for me, since this is going to be used on a local site where the last word is the last name (might not be the whole surname though) but this isn't a problem since all I want is a quick way to say "Dear FIRST_NAME LAST_NAME"... So all this discussion, while totally valid, is useless to me.
Can someone help me with this?
This might not be what you want to hear, but I don't think this problem is suited to a regular expression since names are not regular. I don't think they are even context-sensitive or context-free. If anything, they are unrestricted (I would have to sit down and think that through more than I did before I say that for sure, though) and no regular expression engine can parse an unrestricted grammar.
Instead of a regex you might find it easier to do something like:
$parts = explode(" ", $name);
$first = $parts[0];
$last = ""
if (count($parts) > 1) {
$last = $parts[count($parts) - 1];
}
You might want to replace multiple consecutive bits of whitespace with a single space first, so you don't get empty bits, and get rid of trailing/leading whitespace:
$name = ereg_replace("[ \t\r\n]+", " ", trim($name));
As is, you're requiring a last name -- which, of course, your first example doesn't have.
Use clustered grouping, (?:...), and 0-or-1 count, ?, for the middle and last names as a whole to allow them to be optional:
'~\b(\p{L}+)\b (?: .+\b(\p{L}+)\b )?~ix' # x for spacing
This should allow the first name to be captured whether middle/last names are given or not.
$name = preg_replace('~\b(\p{L}+)\b(?:.+\b(\p{L}+)\b)?~i', '$1 $2', $name);
Depending on how clean your data is, I think you are going to have a tough time finding a single regex that does what you want. What different formats do you expect the names to be in? I've had to write similar code and there can be a lot of variations:
- first last
- last, first
- first middle last
- last, first middle
And then you have things like suffixes (Junior, senior, III, etc.) and prefixes ( Mr., Mrs, etc), combined names (e.g. John and Mary Smith). As some others have already mentioned you also have to deal with multi-part last names (e.g. Victor de la Hoya) as well.
I found I had to deal with all of those possibilities before I could reliably pull out the first and last names.
If you're defining first and last name as the text before the first space and after the last space, then just split the string on spaces and grab the first and last elements of the array.
However, depending on the context/scope of what you're doing, you may need to re-evaluate things - not all names around the world will meet this pattern.
I think your best option is to simply treat everything after the first name as the surname i.e.
William Henry Gates
Forename: William
Surname: Henry Gates
Its the safest mechanism as not everyone will enter their middle name anyway. You can't simply extract William - ignore Henry - and extract Gates as for all you know, Henry is part of the Surname.
Here is simple non regex way
$name=explode(" ",$name);
$first_name=reset($name);
$last_name=end($name);
$result=$first_name.' '.$last_name;