What is the difference between is_numeric(), is_int(), and ctype_digit() functions in PHP?

The difference between is_numeric(), is_int(), and ctype_digit() functions in PHP lies in their specific use cases. is_numeric() checks if a variable is a number or a numeric string, including floats. is_int() specifically checks if a variable is an integer. ctype_digit() checks if all characters in a string are numerical digits. Depending on the specific requirement, you should choose the appropriate function to validate the input.

// Example code snippet demonstrating the use of is_numeric(), is_int(), and ctype_digit()

$number = "123";

if (is_numeric($number)) {
    echo "The variable is a number or a numeric string.\n";
}

if (is_int($number)) {
    echo "The variable is an integer.\n";
} else {
    echo "The variable is not an integer.\n";
}

if (ctype_digit($number)) {
    echo "All characters in the string are numerical digits.\n";
} else {
    echo "The string contains non-digit characters.\n";
}