first.module

<?php
  // $Id$
  /**
  * @file
  * A module exemplifying Drupal coding practices and APIs.
  *
  * This module provides a block that lists all of the
  * installed modules. It illustrates coding standards,
  * practices, and API use for Drupal 7.
  */
  /**
  * Implements hook_help().
  */
  function first_help($path, $arg) {
     // print_r($path); 
      //echo '<pre>';print_r($arg[1]);
  if ($path == 'admin/help#first') {
  return t('A demonstration module.');
   }
  }
  
  
 /*
  function second_help($path, $arg) {
      switch($case) {
          case 'admin/help#first': {
              $ret_val= '<h3>' .t(About) . '</h3>';
              $ret_val .= '<p>' .t(testingmi) .'</p>';
              return $ret_val;
      }
  }
  }
  
  */
  /**
   * hook_permission().
   */
  function first_permission() {
      return array (
          'Administrator first module' => array (
           'title' => t('Adminisrator first module'),
              'description' => t('perform administrator task on first module'),
          
      )
          );
  }
/**
 * implements hook_menu
 */
  function first_menu () {
      $items = array();
      $items['admin/config/first'] =  array (
          'title' => 'first module',
          'description' => 'Administer first settings',
          'access arguments' => array('administer first '),          
      );
      $items['admin/config/first/manage'] = array(
          'title' => 'first module settings',
          'description' => 'manage first module settings and configuration',
          'access arguments' => array('administer first '),
          'page callback' => 'drupal_get_form',
          'page arguments' => array('first_admin_setting_form'),
      );
      return $items;
  }
  /**
   * implements hook_form().
   */
  function first_admin_setting_form($node, &$form_state) {
      $form = array();
      $form['overview'] = array(
        '#markup' => t('Interface for setting for first module'),
          '#prefix' => '<h4>',
          '#suffix' => '</h4>',
        );
      
      $form['first_gmap'] = array(
        '#title' => t('Enable google map'),
          '#Description' => t('enabled google map'),
          '#type' => 'checbox',
          '#defalut_value' => 1,
        );
      
      $form['default_centre'] = array(
        '#title' => t('Map center'),
          '#Description' => t('First field'),
          '#type' => 'fieldset',
          '#collapsible' => TRUE,
          '#collapsed' => FALSE,
        );
      $form['default_centre']['first_default_centre_lat'] = array(
        '#title' => t('interface for setting for first module'),
          '#Description' => t('First field'),
          '#type' => 'textfield',
          '#required' => TRUE,
          '#default_value' => variable_get('first_default_centre_lat'),
        );
      $form['third_field']['fourth_field'] = array(
        '#title' => t('interface for setting for first module'),
          '#Description' => 'First field',
          '#type' => 'textfield',
          '#collapsible' => TRUE,
          '#required' =>TRUE
        );
            $options = range(1, 20, 1);
            $options[0] = t('0');
            $options[20] = t('20');

      $form['third_field']['fifth_field'] = array(
        '#title' => t('interface for setting for first module'),
          '#Description' => t('First field'),
          '#type' => 'select',
          '#options' => $options,
          
        );
      $form['third_field']['sixth_field'] = array(
        '#title' => t('interface for setting for first module'),
          '#Description' => 'First field',
          '#type' => 'select',
          '#options' => $options,
          
        );
      
      $form['submit'] = array(
          '#type' => 'submit',
          '#value' => 'save',
      );          
      
      
      
      return system_settings_form($form);
      
  }
  /**
   * Validate the custom form
   * @param type $form
   * @param type $form_state
   */
  /*
   function  first_admin_setting_form_validate($form, &$form_state) {
   
          dpm($form_state['values']);
          $a = -75.569851;
          $b = $form_state['values']['first_default_centre_lat'];
          if (!preg_match($a, $b)) {
              form_set_error('first_default_centre_lat', t('invalid identifier'));
          }
          
      }
   * /
   */
      /**
       * Submission for a custom form in drupal
       */
      function first_admin_setting_form_submit($form, &$form_state) {
          $form_state['rebuild'] = TRUE;
          variable_set('first_default_centre_lat', $form_state['values']['first_default_centre_lat']);
          drupal_set_message(t('input hass been saved'));
      }
/**
 * 
 * * Implements hook_block_info().
*/
function first_block_info() {
$blocks = array();
$blocks['list_modules'] = array(
'info' => t('A listing of all of the enabled modules.'),
'cache' => DRUPAL_NO_CACHE,
);
return $blocks;
}

/**
* Implements hook_block_view().
*/
function first_block_view($block_name = '') {
if ($block_name == 'list_modules') {
$list = module_list();
$theme_args = array('items' => $list, 'type' => 'ol');
$content = theme('item_list', $theme_args);
$block = array(
'subject' => t('Enabled Modules'),
'content' => $content,
    );
return $block;
}
}