'tag.htm'; break; case 'flag': $pre .= $default_pre .= 'flag.htm'; break; case 'my': $pre .= $default_pre .= 'my.htm'; break; case 'my_password': $pre .= $default_pre .= 'my_password.htm'; break; case 'my_bind': $pre .= $default_pre .= 'my_bind.htm'; break; case 'my_avatar': $pre .= $default_pre .= 'my_avatar.htm'; break; case 'home_article': $pre .= $default_pre .= 'home_article.htm'; break; case 'home_comment': $pre .= $default_pre .= 'home_comment.htm'; break; case 'user': $pre .= $default_pre .= 'user.htm'; break; case 'user_login': $pre .= $default_pre .= 'user_login.htm'; break; case 'user_create': $pre .= $default_pre .= 'user_create.htm'; break; case 'user_resetpw': $pre .= $default_pre .= 'user_resetpw.htm'; break; case 'user_resetpw_complete': $pre .= $default_pre .= 'user_resetpw_complete.htm'; break; case 'user_comment': $pre .= $default_pre .= 'user_comment.htm'; break; case 'single_page': $pre .= $default_pre .= 'single_page.htm'; break; case 'search': $pre .= $default_pre .= 'search.htm'; break; case 'operate_sticky': $pre .= $default_pre .= 'operate_sticky.htm'; break; case 'operate_close': $pre .= $default_pre .= 'operate_close.htm'; break; case 'operate_delete': $pre .= $default_pre .= 'operate_delete.htm'; break; case 'operate_move': $pre .= $default_pre .= 'operate_move.htm'; break; case '404': $pre .= $default_pre .= '404.htm'; break; case 'read_404': $pre .= $default_pre .= 'read_404.htm'; break; case 'list_404': $pre .= $default_pre .= 'list_404.htm'; break; default: $pre .= $default_pre .= theme_mode_pre(); break; } if ($config['theme']) { $conffile = APP_PATH . 'view/template/' . $config['theme'] . '/conf.json'; $json = is_file($conffile) ? xn_json_decode(file_get_contents($conffile)) : array(); } !empty($json['installed']) and $path_file = APP_PATH . 'view/template/' . $config['theme'] . '/htm/' . ($id ? $id . '_' : '') . $pre; (empty($path_file) || !is_file($path_file)) and $path_file = APP_PATH . 'view/template/' . $config['theme'] . '/htm/' . $pre; if (!empty($config['theme_child']) && is_array($config['theme_child'])) { foreach ($config['theme_child'] as $theme) { if (empty($theme) || is_array($theme)) continue; $path_file = APP_PATH . 'view/template/' . $theme . '/htm/' . ($id ? $id . '_' : '') . $pre; !is_file($path_file) and $path_file = APP_PATH . 'view/template/' . $theme . '/htm/' . $pre; } } !is_file($path_file) and $path_file = APP_PATH . ($dir ? 'plugin/' . $dir . '/view/htm/' : 'view/htm/') . $default_pre; return $path_file; } function theme_mode_pre($type = 0) { global $config; $mode = $config['setting']['website_mode']; $pre = ''; if (1 == $mode) { $pre .= 2 == $type ? 'portal_category.htm' : 'portal.htm'; } elseif (2 == $mode) { $pre .= 2 == $type ? 'flat_category.htm' : 'flat.htm'; } else { $pre .= 2 == $type ? 'index_category.htm' : 'index.htm'; } return $pre; } ?>c# - Behavior of the scope concept in local functions - Stack Overflow
最新消息:雨落星辰是一个专注网站SEO优化、网站SEO诊断、搜索引擎研究、网络营销推广、网站策划运营及站长类的自媒体原创博客

c# - Behavior of the scope concept in local functions - Stack Overflow

programmeradmin19浏览0评论

I know how the scope structure works. But while learning local functions, I didn't understand something. I want to ask my question directly with examples.

This code throws an error:

static void Main(string[] args)
{
    int a = 10;

    if (true)
    {
        int a = 10;
    }
}

This code also throws an error:

static void Main(string[] args)
{
    int a = 10;

    {
        int a = 100;
    }
}

I expected the code shown below to also throw an error, but I was wrong. Why?

static void Main(string[] args)
{
    int a = 10;

    void Local()
    {
        int a = 100;
    }
}

I know how the scope structure works. But while learning local functions, I didn't understand something. I want to ask my question directly with examples.

This code throws an error:

static void Main(string[] args)
{
    int a = 10;

    if (true)
    {
        int a = 10;
    }
}

This code also throws an error:

static void Main(string[] args)
{
    int a = 10;

    {
        int a = 100;
    }
}

I expected the code shown below to also throw an error, but I was wrong. Why?

static void Main(string[] args)
{
    int a = 10;

    void Local()
    {
        int a = 100;
    }
}
Share Improve this question edited Jan 18 at 9:22 marc_s 756k184 gold badges1.4k silver badges1.5k bronze badges asked Jan 18 at 9:07 Ekin EkinEkin Ekin 815 bronze badges 1
  • 4 Okay, so you discovered that local functions create a new declaration space. What don't you understand? – Sweeper Commented Jan 18 at 9:10
Add a comment  | 

1 Answer 1

Reset to default 1

a local function creates a completely new scope—like a mini-method—so the variable declared inside the local function doesn’t “collide” with the a in the outer scope. On the other hand, simply using braces { } or an if statement in the same method body does not create a new declaration scope for a to be re-declared.


int a = 10;

if(true)
{
    int a = 10; // ❌ Error: a is already defined in this scope
}

the compiler complains because you’re declaring two variables both named a in overlapping scopes. Even though you’re inside braces, the nested block still can “see” the a from the outer block and is not allowed to re-declare it with the same name.

int a = 10;

{
    int a = 100; // ❌ Error: a is already defined
}

Same reason: the new braces { } do not produce a new “method-like” scope for variable declarations. They are just a nested block within the same local variable scope, so re-declaring a is not allowed.


int a = 10;

void Local()
{
    int a = 100; // ✅ Allowed
}

This does not throw an error because a local function has its own scope, just as if you wrote a separate private method:

private static void Local()
{
    int a = 100; // local to the Local() method
}

Inside that local function, you can re-declare a variable named a, and it doesn’t conflict with the a in the outer method. Essentially, the local function is like a new, nested method that just happens to be declared inside Main. so the Conclusion is :

Blocks { } inside a method do not constitute a fresh “method-level” scope, so you cannot re-declare variables with the same name that are already in scope. A local function does create a completely separate scope (just like a nested method), so re-declaring a variable with the same name is allowed.

发布评论

评论列表(0)

  1. 暂无评论