Check if string is just white space?

Question 1

Possible Duplicate:
If string only contains spaces?

I do not want to change a string nor do I want to check if it contains white space. I want to check if the entire string is ONLY white space. What the best way to do that?

Question 2

This will be the fastest way:

$str = '      ';
if (ctype_space($str)) {

}

Returns false on empty string because empty is not white-space. If you need to include an empty string, you can add || $str == '' This will still result in faster execution than regex or trim.

ctype_space

Question 3

You should point to your vendor/autoload.php at Settings | PHP | PHPUnit when using PHPUnit via Composer.

This blog post has all the details (with pictures) to successfully configure IDE for such scenario: http://confluence.jetbrains.com/display/PhpStorm/PHPUnit+Installation+via+Composer+in+PhpStorm

Related usability ticket: http://youtrack.jetbrains.com/issue/WI-18388

P.S. The WI-18388 ticket is already fixed in v8.0

Question 4

On Mac OS X environment variables available in Terminal and for the normal applications can be different, check the related question for the solution how to make them similar.

Note that this solution will not work on Mountain Lion (10.8).

Question 5

Use the str.isspace() method:

Return True if there are only whitespace characters in the string and there is at least one character, False otherwise.

A character is whitespace if in the Unicode character database (see unicodedata), either its general category is Zs (“Separator, space”), or its bidirectional class is one of WS, B, or S.

Combine that with a special case for handling the empty string.

Alternatively, you could use str.strip() and check if the result is empty.

Question 6

This can be simpliefied a bit

void main(args) {
  print(isNumeric(null));
  print(isNumeric(''));
  print(isNumeric('x'));
  print(isNumeric('123x'));
  print(isNumeric('123'));
  print(isNumeric('+123'));
  print(isNumeric('123.456'));
  print(isNumeric('1,234.567'));
  print(isNumeric('1.234,567'));
  print(isNumeric('-123'));
  print(isNumeric('INFINITY'));
  print(isNumeric(double.INFINITY.toString())); // 'Infinity'
  print(isNumeric(double.NAN.toString()));
  print(isNumeric('0x123'));
}

bool isNumeric(String s) {
  if(s == null) {
    return false;
  }
  return double.parse(s, (e) => null) != null;
}

false   // null  
false   // ''  
false   // 'x'  
false   // '123x'  
true    // '123'  
true    // '+123'
true    // '123.456'  
false   // '1,234.567'  
false   // '1.234,567' (would be a valid number in Austria/Germany/...)
true    // '-123'  
false   // 'INFINITY'  
true    // double.INFINITY.toString()
true    // double.NAN.toString()
false   // '0x123'

from double.parse DartDoc

   * Examples of accepted strings:
   *
   *     "3.14"
   *     "  3.14 xA0"
   *     "0."
   *     ".0"
   *     "-1.e3"
   *     "1234E+7"
   *     "+.12e-9"
   *     "-NaN"

This version accepts also hexadecimal numbers

bool isNumeric(String s) {
  if(s == null) {
    return false;
  }

  // TODO according to DartDoc num.parse() includes both (double.parse and int.parse)
  return double.parse(s, (e) => null) != null || 
      int.parse(s, onError: (e) => null) != null;
}

print(int.parse('0xab'));

true

UPDATE

Since {onError(String source)} is deprecated now you can just use tryParse:

bool isNumeric(String s) {
 if (s == null) {
   return false;
 }
 return double.tryParse(s) != null;
}

Check if string is just white space?

Answers

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