Headers already sent... where? [duplicate]_问答_开发者

This question already has answers here: How to fix "Headers already sent" error in PHP (11 answers) Closed 9 years ago.
Does anyone see how headers could be sent in this script? I am using this script to validate a form. As a result it is causing headers to be sent so when I try to direct a user after implementing this script it causes the normal "Warning: Cannot modify header information - headers already sent" message. Here is the script:
<?php
class ValidatorObj
{
    var $variable_name;
    var $validator_string;
 var $error_string;
} 

/**
* Base class for custom validation objects
**/
 class CustomValidator 
 {
    function DoValidate(&$formars,&$error_hash)
{
    return true;
}
}

/** Default error messages*/
define("E_VAL_REQUIRED_VALUE","Please enter the value for %s");
define("E_VAL_MAXLEN_EXCEEDED","Maximum length exceeded for %s.");
define("E_VAL_MINLEN_CHECK_FAILED","Please enter input with length more than %d for %s");
define("E_VAL_ALNUM_CHECK_FAILED","Please provide an alpha-numeric input for %s");
define("E_VAL_ALNUM_S_CHECK_FAILED","Please provide an alpha-numeric input for %s");
define("E_VAL_NUM_CHECK_FAILED","Please provide numeric input for %s");
define("E_VAL_ALPHA_CHECK_FAILED","Please provide alphabetic input for %s");
define("E_VAL_ALPHA_S_CHECK_FAILED","Please provide alphabetic input for %s");
define("E_VAL_EMAIL_CHECK_FAILED","Please provide a valida email address");
define("E_VAL_LESSTHAN_CHECK_FAILED","Enter a value less than %f for %s");
define("E_VAL_GREATERTHAN_CHECK_FAILED","Enter a value greater than %f for %s");
define("E_VAL_REGEXP_CHECK_FAILED","Please provide a valid input for %s");
define("E_VAL_DONTSEL_CHECK_FAILED","Wrong option selected for %s");
define("E_VAL_SELMIN_CHECK_FAILED","Please select minimum %d options for %s");
define("E_VAL_SELONE_CHECK_FAILED","Please select an option for %s");
define("E_VAL_EQELMNT_CHECK_FAILED","Value of %s should be same as that of %s");
define("E_VAL_NEELMNT_CHECK_FAILED","Value of %s should not be same as that of %s");

class FormValidator 
{
    var $validator_array;
    var $error_hash;
    var $custom_validators;

function FormValidator()
{
    $this->validator_array = array();
    $this->error_hash = array();
    $this->custom_validators=array();
}

function AddCustomValidator(&$customv)
{
    array_push($this->custom_validators,$customv);
}

function addValidation($variable,$validator,$error)
{
    $validator_obj = new ValidatorObj();
    $validator_obj->variable_name = $variable;
    $validator_obj->validator_string = $validator;
    $validator_obj->error_string = $error;
    array_push($this->validator_array,$validator_obj);
}
function GetErrors()
{
    return $this->error_hash;
}

function ValidateForm()
{
    $bret = true;

    $error_string="";
    $error_to_display = "";


    if(strcmp($_SERVER['REQUEST_METHOD'],'POST')==0)
    {
        $form_variables = $_POST;
    }
    else
    {
        $form_variables = $_GET;
    }

    $vcount = count($this->validator_array);


    foreach($this->validator_array as $val_obj)
    {
        if(!$this->ValidateObject($val_obj,$form_variables,$error_string))
        {
            $bret = false;
            $this->error_hash[$val_obj->variable_name] = $error_string;
        }
    }

    if(true == $bret && count($this->custom_validators) > 0)
    {
        foreach( $this->custom_validators as $custom_val)
        {
            if(false == $custom_val->DoValidate($form_variables,$this->error_hash))
            {
                $bret = false;
            }
        }
    }
    return $bret;
}


function ValidateObject($validatorobj,$formvariables,&$error_string)
{
    $bret = true;

    $splitted = explode("=",$validatorobj->validator_string);
    $command = $splitted[0];
    $command_value = '';

    if(isset($splitted[1]) && strlen($splitted[1])>0)
    {
        $command_value = $splitted[1];
    }

    $default_error_message="";

    $input_value ="";

    if(isset($formvariables[$validatorobj->variable_name]))
    {
     $input_value = $formvariables[$validatorobj->variable_name];
    }

    $bret = $this->ValidateCommand($command,$command_value,$input_value,
                                $default_error_message,
                                $validatorobj->variable_name,
                                $formvariables);


    if(false == $bret)
    {
        if(isset($validatorobj->error_string) &&
            strlen($validatorobj->error_string)>0)
        {
            $error_string = $validatorobj->error_string;
        }
        else
        {
            $error_string = $default_error_message;
        }

    }//if
    return $bret;
}

function validate_req($input_value, &$default_error_message,$variable_name)
{
  $bret = true;
    if(!isset($input_value) ||
        strlen($input_value) <=0)
    {
        $bret=false;
        $default_error_message = sprintf(E_VAL_REQUIRED_VALUE,$variable_name);
    }   
  return $bret; 
}

function validate_maxlen($input_value,$max_len,$variable_name,&$default_error_message)
{
    $bret = true;
    if(isset($input_value) )
    {
        $input_length = strlen($input_value);
        if($input_length > $max_len)
        {
            $bret=false;
            $default_error_message = sprintf(E_VAL_MAXLEN_EXCEEDED,$variable_name);
        }
    }
    return $bret;
}

function validate_minlen($input_value,$min_len,$variable_name,&$default_error_message)
{
    $bret = true;
    if(isset($input_value) )
    {
        $input_length = strlen($input_value);
        if($input_length < $min_len)
        {
            $bret=false;
            $default_error_message = sprintf(E_VAL_MINLEN_CHECK_FAILED,$min_len,$variable_name);
        }
    }
    return $bret;
}

function test_datatype($input_value,$reg_exp)
{
    if(ereg($reg_exp,$input_value))
    {
        return false;
    }
    return true;
}

function validate_email($email) 
{
    return eregi("^[_\.0-9a-zA-Z-]+@([0-9a-zA-Z][0-9a-zA-Z-]+\.)+[a-zA-Z]{2,6}$", $email);
}

function validate_for_numeric_input($input_value,&$validation_success)
{

    $more_validations=true;
    $validation_success = true;
    if(strlen($input_value)>0)
    {

        if(false == is_numeric($input_value))
        {
            $validation_success = false;
            $more_validations=false;
        }
    }
    else
    {
        $more_validations=false;
    }
    return $more_validations;
}

function validate_lessthan($command_value,$input_value,
            $variable_name,&$default_error_message)
{
    $bret = true;
    if(false == $this->validate_for_numeric_input($input_value,
                                $bret))
    {
        return $bret;
    }
    if($bret)
    {
        $lessthan = doubleval($command_value);
        $float_inputval = doubleval($input_value);
        if($float_inputval >= $lessthan)
        {
            $default_error_message = sprintf(E_VAL_LESSTHAN_CHECK_FAILED,
                                    $lessthan,
                                    $variable_name);
            $bret = false;
        }//if
    }
    return $bret ;
}

function validate_greaterthan($command_value,$input_value,$variable_name,&$default_error_message)
{
    $bret = true;
    if(false == $this->validate_for_numeric_input($input_value,$bret))
    {
        return $bret;
    }
    if($bret)
    {
        $greaterthan = doubleval($command_value);
        $float_inputval = doubleval($input_value);
        if($float_inputval <= $greaterthan)
        {
            $default_error_message = sprintf(E_VAL_GREATERTHAN_CHECK_FAILED,
                                    $greaterthan,
                                    $variable_name);
            $bret = false;
        }//if
    }
    return $bret ;
}

function validate_select($input_value,$command_value,&$default_error_message,$variable_name)
{
    $bret=false;
    if(is_array($input_value))
    {
        foreach($input_value as $value)
        {
            if($value == $command_value)
            {
                $bret=true;
                break;
            }
        }
    }
    else
    {
        if($command_value == $input_value)
        {
            $bret=true;
        }
    }
    if(false == $bret)
    {
        $default_error_message = sprintf(E_VAL_SHOULD_SEL_CHECK_FAILED,
                                        $command_value,$variable_name);
    }
    return $bret;
}

function validate_dontselect($input_value,$command_value,&$default_error_message,$variable_name)
{
   $bret=true;
    if(is_array($input_value))
    {
        foreach($input_value as $value)
        {
            if($value == $command_value)
            {
                $bret=false;
                $default_error_message = sprintf(E_VAL_DONTSEL_CHECK_FAILED,$variable_name);
                break;
            }
        }
    }
    else
    {
        if($command_value == $input_value)
        {
            $bret=false;
            $default_error_message = sprintf(E_VAL_DONTSEL_CHECK_FAILED,$variable_name);
        }
    }
  return $bret;
}



function ValidateCommand($command,$command_value,$input_value,&$default_error_message,$variable_name,$formvariables)
{
    $bret=true;
    switch($command)
    {
        case 'req':
                    {
                        $bret = $this->validate_req($input_value, $default_error_message,$variable_name);
                        break;
                    }

        case 'maxlen':
                    {
                        $max_len = intval($command_value);
                        $bret = $this->validate_maxlen($input_value,$max_len,$variable_name,
                                            $default_error_message);
                        break;
                    }

        case 'minlen':
                    {
                        $min_len = intval($command_value);
                        $bret = $this->validate_minlen($input_value,$min_len,$variable_name,
                                        $default_error_message);
                        break;
                    }

        case 'alnum':
                    {
                        $bret= $this->test_datatype($input_value,"[^A-Za-z0-9]");
                        if(false == $bret)
                        {
                            $default_error_message = sprintf(E_VAL_ALNUM_CHECK_FAILED,$variable_name);
                        }
                        break;
                    }

        case 'alnum_s':
                    {
                        $bret= $this->test_datatype($input_value,"[^A-Za-z0-9 ]");
                        if(false == $bret)
                        {
                            $default_error_message = sprintf(E_VAL_ALNUM_S_CHECK_FAILED,$variable_name);
                        }
                        break;
                    }

        case 'num':
        case 'numeric':
                    {
                        $bret= $this->test_datatype($input_value,"[^0-9]");
                        if(false == $bret)
                        {
                            $default_error_message = sprintf(E_VAL_NUM_CHECK_FAILED,$variable_name);
                        }
                        break;                          
                    }

        case 'alpha':
                    {
                        $bret= $this->test_datatype($input_value,"[^A-Za-z]");
                        if(false == $bret)
                        {
                            $default_error_message = sprintf(E_VAL_ALPHA_CHECK_FAILED,$variable_name);
                        }
                        break;
                    }
        case 'alpha_s':
                    {
                        $bret= $this->test_datatype($input_value,"[^A-Za-z ]");
                        if(false == $bret)
                        {
                            $default_error_message = sprintf(E_VAL_ALPHA_S_CHECK_FAILED,$variable_name);
                        }
                        break;
                    }
        case 'email':
                    {
                        if(isset($input_value) && strlen($input_value)>0)
                        {
                            $bret= $this->validate_email($input_value);
                            if(false == $bret)
                            {
                                $default_error_message = E_VAL_EMAIL_CHECK_FAILED;
                            }
                        }
                        break;
                    }
        case "lt": 
        case "lessthan": 
                    {
                        $bret = $this->validate_lessthan($command_value,
                                                $input_value,
                                                $variable_name,
                                                $default_error_message);
                        break;
                    }
        case "gt": 
        case "greaterthan": 
                    {
                        $bret = $this->validate_greaterthan($command_value,
                                                $input_value,
                                                $variable_name,
                                                $default_error_message);
                        break;
                    }

        case "regexp":
                    {
                        if(isset($input_value) && strlen($input_value)>0)
                        {
                            if(!preg_match("$command_value",$input_value))
                            {
                                $bret=false;
                                $default_error_message = sprintf(E_VAL_REGEXP_CHECK_FAILED,$variable_name);
                            }
                        }
                        break;
                    }
      case "dontselect": 
      case "dontselectchk":
      case "dontselectradio":
                    {
                        $bret = $this->validate_dontselect($input_value,
                                                           $command_value,
                                                           $default_error_message,
                                                            $variable_name);
                         break;
                    }//case

      case "shouldselchk":
      case "selectradio":
                  {
                        $bret = $this->validate_select($input_value,
                               $command_value,
                               $default_error_message,
                                $variable_name);
                        break;
                  }//case
      case "selmin":
                    {
                        $min_count = intval($command_value);

                        if(isset($input_value))
                        {
                            if($min_count > 1)
                            {
                                $bret = (count($input_value) >= $min_count )?true:false;
                            }
                            else
                            {
                              $bret = true;
                            }
                        }
                        else
                        {
                            $bret= false;
                            $default_error_message = sprintf(E_VAL_SELMIN_CHECK_FAILED,$min_count,$variable_name);
                        }

                        break;
                    }//case
     case "selone":
                    {
                        if(false == isset($input_value)||
                            strlen($input_value)<=0)
                        {
                            $bret= false;
                            $default_error_message = sprintf(E_V开发者_如何学CAL_SELONE_CHECK_FAILED,$variable_name);
                        }
                        break;
                    }
     case "eqelmnt":
                    {

                        if(isset($formvariables[$command_value]) &&
                           strcmp($input_value,$formvariables[$command_value])==0 )
                        {
                            $bret=true;
                        }
                        else
                        {
                            $bret= false;
                            $default_error_message = sprintf(E_VAL_EQELMNT_CHECK_FAILED,$variable_name,$command_value);
                        }
                    break;
                    }
      case "neelmnt":
                    {
                        if(isset($formvariables[$command_value]) &&
                           strcmp($input_value,$formvariables[$command_value]) !=0 )
                        {
                            $bret=true;
                        }
                        else
                        {
                            $bret= false;
                            $default_error_message = sprintf(E_VAL_NEELMNT_CHECK_FAILED,$variable_name,$command_value);
                        }
                        break;
                    }
    }//switch
    return $bret;
}//validdate command
}?>
after .the }?>
if you select all (Ctrl+A) you will see the white space proceeding the ?>
There is likely whitespace after the closing ?> tag. It's become quite common practice to leave off the ending ?> tag to prevent this exactly issue. But that can only be done in files that contain only code in classes, no procedural code.
To add on to RobertPitt, if your file is solely PHP only, add the <?php at the start, and remove the ?> to prevent careless whitespaces at the back.