Check If a Character Is Lowercase or Uppercase

How can I test if a letter in a string is uppercase or lowercase using JavaScript?

The answer by josh and maleki will return true on both upper and lower case if the character or the whole string is numeric. making the result a false result.
example using josh

var character = '5';
if (character == character.toUpperCase()) {
 alert ('upper case true');
}
if (character == character.toLowerCase()){
 alert ('lower case true');
}

another way is to test it first if it is numeric, else test it if upper or lower case
example

var strings = 'this iS a TeSt 523 Now!';
var i=0;
var character='';
while (i <= strings.length){
    character = strings.charAt(i);
    if (!isNaN(character * 1)){
        alert('character is numeric');
    }else{
        if (character == character.toUpperCase()) {
            alert ('upper case true');
        }
        if (character == character.toLowerCase()){
            alert ('lower case true');
        }
    }
    i++;
}

How to check if a char and/or string is uppercase or lowercase

This will work:

char hLow = 'h';         
char hHigh = 'H';        

char.IsLower(hLow);      //returns true
char.IsUpper(hHigh);     //returns true

This would work as well (but it's a rather old-school approach to it and doesn't work for accent letters):

(hLow >= 'a' && hLow <= 'z');      //returns true
(hHigh >= 'A' && hHigh <= 'Z');     //returns true

Also, if you want to check if all characters in a string are uppercase/lowercase, you can do it like this:

string word = "UPPERCASE";

word.All(char.IsUpper);     //returns true
word.All(char.IsLower);     //returns false

Keep in mind that you need to have using System.Linq; in the beginning of your code for this to work.

And if you want to check if a string only contains letters, just use this (still using Linq):

word.All(char.IsLetter);    //returns true

There are more useful functions like this in Linq which you can find yourself.

Check if a character is lowerCase or upperCase

 var input = "The quick BroWn fOX jumpS Over tHe lazY DOg"

 var inputArray = Array(input)

 for character in inputArray {

 var strLower = "[a-z]";

 var strChar = NSString(format: "%c",character )
 let strTest = NSPredicate(format:"SELF MATCHES %@", strLower );
 if strTest .evaluateWithObject(strChar)
 {
   // lower character
 }
 else
 {
   // upper character
 }
}

Check if all letter is uppercase or lowercase python, if there is one word in string is different print none

No need for loops here. Just simply use the functions isupper() and islower() in an if-elif block, and add an else block to take care of mixed case (i.e., print out None or NONE), like so:

test_str = input()
    
if test_str.isupper():
    print('UPPER')
elif test_str.islower():
    print('LOWER')
else:
    print(None) # or print('NONE')

Example input/output:

HELLO USER
UPPER

HELLO UsER    
None 

hello user  
LOWER

hello User
None 

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Active reading: GeeksForGeeks

How to check if a string is all upper or lower case in Go?

You can of course compare the upper and lower cased strings in their entirety, or you can short-circuit the comparisons on the first failure, which would be more efficient when comparing long strings.

func IsUpper(s string) bool {
    for _, r := range s {
        if !unicode.IsUpper(r) && unicode.IsLetter(r) {
            return false
        }
    }
    return true
}

func IsLower(s string) bool {
    for _, r := range s {
        if !unicode.IsLower(r) && unicode.IsLetter(r) {
            return false
        }
    }
    return true
}

How do I detect if a character is uppercase or lowercase?

BOOL isUppercase = [[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[s characterAtIndex:0]];

How to check if letter is upper or lower in PHP?

It is my opinion that making a preg_ call is the most direct, concise, and reliable call versus the other posted solutions here.

echo preg_match('~^\p{Lu}~u', $string) ? 'upper' : 'lower';

My pattern breakdown:

~      # starting pattern delimiter 
^      #match from the start of the input string
\p{Lu} #match exactly one uppercase letter (unicode safe)
~      #ending pattern delimiter 
u      #enable unicode matching

Please take notice when ctype_ and < 'a' fail with this battery of tests.

Code: (Demo)

$tests = ['âa', 'Bbbbb', 'Éé', 'iou', 'Δδ'];

foreach ($tests as $test) {
    echo "\n{$test}:";
    echo "\n\tPREG:  " , preg_match('~^\p{Lu}~u', $test)      ? 'upper' : 'lower';
    echo "\n\tCTYPE: " , ctype_upper(mb_substr($test, 0, 1))  ? 'upper' : 'lower';
    echo "\n\t< a:   " , mb_substr($test, 0, 1) < 'a'         ? 'upper' : 'lower';

    $chr = mb_substr ($test, 0, 1, "UTF-8");
    echo "\n\tMB:    " , mb_strtoupper($chr, "UTF-8") == $chr ? 'upper' : 'lower';
}

Output:

âa:
    PREG:  lower
    CTYPE: lower
    < a:   lower
    MB:    lower
Bbbbb:
    PREG:  upper
    CTYPE: upper
    < a:   upper
    MB:    upper
Éé:               <-- trouble
    PREG:  upper
    CTYPE: lower  <-- uh oh
    < a:   lower  <-- uh oh
    MB:    upper
iou:
    PREG:  lower
    CTYPE: lower
    < a:   lower
    MB:    lower
Δδ:               <-- extended beyond question scope
    PREG:  upper  <-- still holding up
    CTYPE: lower
    < a:   lower
    MB:    upper  <-- still holding up

If anyone needs to differentiate between uppercase letters, lowercase letters, and non-letters see this post.

---

It may be extending the scope of this question too far, but if your input characters are especially squirrelly (they might not exist in a category that Lu can handle), you may want to check if the first character has case variants:

\p{L&} or \p{Cased_Letter}: a letter that exists in lowercase and uppercase variants (combination of Ll, Lu and Lt).

• Source: https://www.regular-expressions.info/unicode.html

To include Roman Numerals ("Number Letters") with SMALL variants, you can add that extra range to the pattern if necessary.

https://www.fileformat.info/info/unicode/category/Nl/list.htm

Code: (Demo)

echo preg_match('~^[\p{Lu}\x{2160}-\x{216F}]~u', $test) ? 'upper' : 'not upper';

How to check if string has lowercase letter, uppercase letter and number

You have some problems with your checking logic. First of all you re-set your control variables before the while condition could check them. Furthermore you used and to test if all conditions are true, while or is what you should be using. If you want to keep the basic structure of your code, the best way to go is to use only True in your while statement and then break the loop once all conditions are fulfilled. Of course, as shown in the other answers, there are much more compact ways to check that all conditions are fulfilled.

passwd = raw_input("enter your password: ")
upper = 0
lower = 0 
number = 0
while True:
    for x in passwd:
        if x.isupper()==True:
            print 'upper'
            upper+=1
        elif x.islower()==True:
            print 'lower'
            lower+=1
        elif x.isalpha()==False:
            print 'num'
            number+=1
    if len(passwd) < 7 or upper <= 0 or lower <= 0 or number <= 0:
        print ('password not complex enough')
        passwd = raw_input('please enter password again ')
        upper = 0
        lower = 0
        number = 0
    else:
        break

print 'final password:', passwd

Output:

enter your password: pA
lower
upper
password not complex enough
please enter password again pA1ghlfx78
lower
upper
num
lower
lower
lower
lower
lower
num
num
final password: pA1ghlfx78

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