Question

How to check if a word is all uppercase or lowercase or capitalized in PHP

Answer 1

function VerifyAllUpperOrAllLowerOrIsCapitalized(string $word): bool {
    $upper = 0;
    $lower = 0;
    $length = strlen($word);

    for ($i = 0; $i < $length; $i++) {
        $ch = $word[$i];
        if (ctype_lower($ch)) {
            $lower++;
        } elseif (ctype_upper($ch)) {
            $upper++;
        }
    }

    // Case 1: all lowercase
    if ($upper === 0) return true;

    // Case 2: all uppercase
    if ($lower === 0) return true;

    // Case 3: capitalized (only first letter uppercase)
    if ($upper === 1 && ctype_upper($word[0])) return true;

    // Otherwise, mixed casing
    return false;
}

/**
 * Runs a test case and prints the result
 */
function runTest(string $word): void {
    echo "Testing word: \"$word\"\n";
    if (VerifyAllUpperOrAllLowerOrIsCapitalized($word)) {
        echo "OK\n\n";
    } else {
        echo "Error\n\n";
    }
}

runTest("PROGRAMMING");   
runTest("programming");   
runTest("Programming");   
runTest("ProGramMing");   



/*
run:

Testing word: "PROGRAMMING"
OK

Testing word: "programming"
OK

Testing word: "Programming"
OK

Testing word: "ProGramMing"
Error

*/

 

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