Library/Think/Http/Request.class.php
/**
     * Get Headers
     *
     * This method returns a key-value array of headers sent in the HTTP request, or
     * the value of a hash key if requested; if the array key does not exist, NULL is returned.
     *
     * @param  string  $key
     * @param  mixed   $default The default value returned if the requested header is not available
     * @return mixed
     */
Get Headers
This method returns a key-value array of headers sent in the HTTP request, or
the value of a hash key if requested; if the array key does not exist, NULL is returned.

@param  string  $key
@param  mixed   $default The default value returned if the requested header is not available
@return mixed
Get Headers This method returns a key - value array of headers sent in the HTTP request or the value of a hash key if requested ; if the array key does not exist NULL is returned . @param string $key @param mixed $default The default value returned if the requested header is not available @return mixed
public function headers($key = null, $default = null) {
        if ($key) {
            return $this->headers->get($key, $default);
        }
        return $this->headers;
    }
public function headers ( $ key = null , $ default = null ) { if ( $ key ) { return $ this -> headers -> get ( $ key , $ default ) ; } return $ this -> headers ; }
Get Headers
 This method returns a key-value array of headers sent in the HTTP request, or
 the value of a hash key if requested; if the array key does not exist, NULL is returned.
Get Headers This method returns a key - value array of headers sent in the HTTP request or the value of a hash key if requested ; if the array key does not exist NULL is returned .