Some Regular expresstion

hi, i don't know how write regexp (preg_match() in php) and i wanna following regexps:
1. just number
2. just words
3. just words, numbers, -._
tanks.

Code:

---

$reg1 = preg_match("/[0-9]/", "String to check");  // Only numbers
$reg2 = preg_match("/[a-z]/i", "String to check");  // Only letters
$reg3 = preg_match("/[a-z0-9-._]/i", "String to check");  // numbers, letters and -._

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There are a few different ways to use those regular expressions but I laid out a simple preg_match function stored in each variable above.

Those checks are all well and good, if all you want to know if is the string contains "a letter" , "a number" or "a letter, number, hyphen, period, or underscore".

I'm going to assume this is for validating some type of login or password?

If that's the case, you probably want to check for things OTHER than what you want.

Take a look at these examples:

PHP Code:

---

    $test_string = "Str1ng-t0_ch3ck.";
    $test_string_words = "Stringtocheck";
    $test_string_numbers = "12345";
    $test_string_mixed = "Str1ng t0 ch3ck.";    // note the added spaces; need to add \s to the regex patterns to match this
    
    $reg1 = preg_match("/[^0-9]/", $test_string);  // Only numbers
    $reg1a = preg_match("/[^0-9]/", $test_string_numbers);  // Only numbers

    $reg2 = preg_match("/[^a-z]/i", $test_string);  // Only letters
    $reg2a = preg_match("/[^a-z]/i", $test_string_words);  // Only letters
    
    $reg3 = preg_match("/[^a-z0-9-._]/i", $test_string);  // numbers, letters and -._

    $reg4 = preg_match("/[^\w-._]/i", $test_string_mixed);  // numbers, letters and -._    
    

    /*
    preg_match returns int(1) if it finds a match to the pattern or int(0) if it does not find a match.
    since these checks are checking for NOT IN THE PATTERN, then (if $var === 0) "passes" the regex and (if $var === 1) "fails"
        {three "equal signs" matches exactly the type int()} 
    ------------ reg1 (it found something other than just numbers)
    1
    ------------ 
    ------------ reg1a (it found only numbers)
    0
    ------------ 
    ------------ reg2 (it found something other than just letters)
    1
    ------------ 
    ------------ reg2a (it found only letters)
    0
    ------------ 
    ------------ reg3 (it found only the acceptable characters)
    0
    ------------ 
    ------------ reg4 (condensed "word boundries (letter and numbers) plus the `extra characters`")
    1
    ------------ 
    
    */ 


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Also, please see the various ctype_*() functions for more efficient ways to do certain checks.

i want check input and
1.if it was just numbers return 1 and if it has characters return 0.
2.if it was just characters return 1 and if it has numbers return 0.
3.if it was just characters and numbers return 1 and if it has else characters line &,*,... return 0.
3.if it was just characters and numbers and -_. return 1 and if it has else characters line &,*,... return 0.