Check if string is a punctuation character

Question

Let's say I have a String array that contains some letters and punctuation

String letter[] = {"a","b","c",".","a"};

In letter[3] we have "."

How can I check if a string is a punctuation character? We know that there are many possible punctuation characters (,.?! etc.)

My progress so far:

for (int a = 0; a < letter.length; a++) {
    if (letter[a].equals(".")) { //===>> i'm confused in this line
        System.out.println ("it's punctuation");
    } else {
        System.out.println ("just letter");
    }
}

This will give you some idea: [Punctuation Regex in Java](http://stackoverflow.com/questions/8200908/punctuation-regex-in-java) — Stanley, Dec 18 '12 at 02:39
@sephtian Sorry for late reply. Although I added answer if you want to make use of it. — Smit, Dec 18 '12 at 03:27

score 65 · Answer 1 · answered Dec 18 '12 at 02:41

65

Here is one way to do it with regular expressions:

if (Pattern.matches("\\p{Punct}", str)) {
    ...
}

The \p{Punct} regular expression is a POSIX pattern representing a single punctuation character.

answered Dec 18 '12 at 02:41

Sergey Kalinichenko

714,442
84
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score 33 · Answer 2 · answered Mar 15 '18 at 00:32

Depending on your needs, you could use either

Pattern.matches("\\p{Punct}", str)

or

Pattern.matches("\\p{IsPunctuation}", str)

The first pattern matches the following 32 characters: !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

The second pattern matches a whopping 632 unicode characters, including, for example: «, », ¿, ¡, §, ¶, ‘, ’, “, ”, and ‽.

Interestingly, not all of the 32 characters matched by the first pattern are matched by the second. The second pattern does not match the following 9 characters: $, +, <, =, >, ^, `, |, and ~ (which the first pattern does match).

If you want to match for any character from either character set, you could do:

Pattern.matches("[\\p{Punct}\\p{IsPunctuation}]", str)

Where is Pattern coming from in this example? I"m getting an error "VM718:1 Uncaught ReferenceError: Pattern is not defined" — Parseltongue, Oct 22 '20 at 19:22

score 21 · Accepted Answer · edited Nov 28 '18 at 13:47

21

Do you want to check more punctuations other than just .?

If so you can do this.

String punctuations = ".,:;";//add all the punctuation marks you want.
...
if(punctuations.contains(letter[a]))

edited Nov 28 '18 at 13:47

Community

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1

answered Dec 18 '12 at 02:40

Karthik T

31,456
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4

This solution implies that you manually specify all punctuation marks. The definition of 'punctuation' is definitely incomplete. – Frank-Rene Schäfer Mar 09 '16 at 08:44
1

This is not enough. There are lots of languages that have different punctuation signs. These not even cover the Latin Alphabet. Use \p{P} or \p{Punctuation} instead – andreyro Jan 16 '18 at 08:42
1

This is incomplete and improper solution @Hans Brende should be selected as correct ans – Jabir May 10 '23 at 12:55

score 3 · Answer 4 · answered Dec 18 '12 at 02:39

3

Try this method: Character.isLetter(). It returns true if the character is a letter (a-z, uppercase or lowercase), returns false if character is numeric or symbol.

e.g. boolean answer = Character.isLetter('!');

answer will be equal to false.

answered Dec 18 '12 at 02:39

Jj Tuibeo

773
4
18

the problem with that solution is when you are checking for special chars like % ^$ .. you will always get false and they are not letters – mebada Aug 03 '18 at 20:19
@mebada what's the problem? – superPhreshHackerKid May 16 '20 at 19:51

score 1 · Answer 5 · answered Jun 10 '21 at 07:45

I have tried regex: "[\\p{Punct}]" or "[\\p{IsPunctuation}]" or withouth [], it doesn't work as expected.

My string is: How are you?, or even "How are you?", he asked.

Then call: my_string.matches(regex); but it seems like it only recognises if the string is only one punctuation (e.g "?", ".",...).

Only this regex works for me: "(.*)[\\p{P}](.*)", it will include all preceding and proceeding characters of the punctuation because the matches() requires to match all the sentence.

score -3 · Answer 6 · answered Jan 31 '19 at 22:32

-3

import String ... if(string.punctuation.contains(letter[a]))

answered Jan 31 '19 at 22:32

jfranzoy

35
7

score -5 · Answer 7 · answered Jun 17 '15 at 20:42

-5

function has_punctuation(str) {

  var p_found = false;
  var punctuations = '`~!@#$%^&*()_+{}|:"<>?-=[]\;\'.\/,';
  $.each(punctuations.split(''), function(i, p) {
    if (str.indexOf(p) != -1) p_found = true;
  });

  return p_found;

}

answered Jun 17 '15 at 20:42

Rob Korobkin

19

1

this question asked for java, not javascript. – Allan J. Oct 26 '21 at 04:01

Check if string is a punctuation character

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