Hola
Goomba
Prueba este ejemplo:
Código PHP:
<html>
<head>
<script type="text/javascript">
function validar(frm) {
for (i=0; ele = frm['caracteristica[]'][i]; i++)
if (ele.checked) return
return false;
}
</script>
</head>
<body>
<form onsubmit="return validar(this)">
<input type="checkbox" name="caracteristica[]" value="<?php echo $result[$i] ?>">
<input type="checkbox" name="caracteristica[]" value="<?php echo $result[$i] ?>">
<input type="checkbox" name="caracteristica[]" value="<?php echo $result[$i] ?>">
<input type="submit" />
</form>
</body>
</html>
Saludos,