Required fields in multiple checkbox and radio button - php

Question

In html for radio button I have this:
<input type="radio" name="sex" value="male" /> Male<br />
<input type="radio" name="sex" value="female" /> Female <br />
and for check list:
<input name="checkboxvar[]" type="checkbox" value="dog" />Dog</td>
<input name="checkboxvar[]" type="checkbox" value="cat" />Cat</td>
<input name="checkboxvar[]" type="checkbox" value="rabbit" />Rabbit</td>
For the radio buttons how can I make them required and for the checkbox to take the result if the user select more than 1 values?
For the previous fields I use a submit button
<input type="submit" name="submit" id="submit" value="submit" />

Answer 1

by using required attribute as follows:-
<input type="radio" name="sex" value="male" required />Male

Answer 2

For making a radio button required, use the required tag (you only need add the required tag for one radio input per group):
<input type="radio" name="sex" value="male" required/> Male<br />
The required attribute is shorthand for required="required" or required="true" (the fact that its there constitutes a 'truthy' value, as does any (nonempty) string).
For making at least one of the checkboxes required: An answer has already been provided here; this basically states that, given a <button> element with and id of checkBtn, the following code can help (with some of my comments on it):
$(document).ready(function () {
// grabbing the button's element and adding an
// onclick event to it
$('#checkBtn').click(function() {
// grabs all elements which are checkboxes and
// are checked; if none are checked, the length
// is zero; else, the length is a 'truthy' value
checked = $("input[type=checkbox]:checked").length;
// if no elements are checked
if(!checked) {
// error handling
alert("You much check at least one checkbox.") return false;
}
});
});
Assuming that you want to detect the error upon the submit button's click; if you want to handle the error otherwise, you might want to clarify that (your answer is a tad vague).
Hope it helps!