how can i input a validation PHP

Question

Good day!

How can I produce an error if i input a letter instead of number because characters can still be encoded.... My code is as follows:

<HTML>
<BODY>

Please enter your grade (0-100 only):
<FORM ACTION="grade.php" METHOD="POST">
<table border = "1">
    <tr>
        <td>Grade</td>
        <td><input type="text" name="grade" /></td>
    </tr>
</table>
<INPUT type="submit" name="submit" value="grade status">
</FORM>
<?php

$grade = $_POST['grade'];
IF ($grade>=0 && $grade<=50){
    print "You failed";
} ELSE IF ($grade<=60){
    print "You Passed! But Study Harder!";
} ELSE IF ($grade<=70){
    print "Nice";
} ELSE IF ($grade<=80) {
    print "Great Job";
} ELSE IF ($grade<=90){
    print "Excellent";
} ELSE IF ($grade<=100){
    print "God Like!";
} ELSE {
    print "Invalid Grade!";
}   
?>

</BODY>
</HTML>

If you're using HTML5 you can do this with a number input type html5doctor.com/html5-forms-input-types , but make sure to always validate on the client-side. — Jay Blanchard
– Jay Blanchard, Commented Nov 7, 2017 at 15:26

Dan · Accepted Answer · 2014-09-11 14:09:23Z

3

Check the input text's ascii to see if it is number or not!

or use is_numeric($var);

edited Sep 11, 2014 at 14:09

Dan

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answered Apr 7, 2011 at 5:59

Sourav

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2 Comments

Sourav Over a year ago

use echo not print, coz it's slightly faster as prints returns 0/1

Pascal MARTIN Over a year ago

@newbie just know that is_numeric() will return true for things that are not 0-9 ;; for example, is_numeric('-1.5e5') is true.

Community · Accepted Answer · 2023-11-17 19:42:58Z

1

To check if something only contains digits, see the ctype_digit() function.

edited Nov 17, 2023 at 19:42

CommunityBot

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answered Apr 7, 2011 at 6:04

Pascal MARTIN

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Comments

thkala · Accepted Answer · 2012-01-06 18:47:59Z

1

Use javascript:

<script language="javascript">
function isInteger(s)
{   var i=document.s.grad.value;
    for (i = 0; i < s.length; i++)
    {
        // Check that current character is number.
        var c = s.charAt(i);
        if (((c < "0") || (c > "9"))) 
            {
alert("Must Enter Number");
            return false;
            }
    }
    // All characters are numbers.
    return true;
}

</script>

and call this function in form tab

<FORM ACTION="grade.php" METHOD="POST" onSubmint="isInteger(this)">

edited Jan 6, 2012 at 18:47

thkala

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answered Apr 7, 2011 at 6:18

bhavesh N

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Comments

Vishal · Accepted Answer · 2014-09-11 14:07:45Z

0

You can use regular expression

if (preg_match('/^[0-9]+$/', $str)) {

} else {

}

answered Sep 11, 2014 at 14:07

Vishal

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