Codechange: Use null pointer literal instead of the NULL macro

8 files changed, 74 insertions, 74 deletions

diff --git a/src/ai/ai_config.cpp b/src/ai/ai_config.cpp
index a78281478..93db57158 100644
--- a/src/ai/ai_config.cpp
+++ b/src/ai/ai_config.cpp
@@ -31,7 +31,7 @@ ScriptConfigItem _start_date_config = {
 	AI::START_NEXT_DEVIATION,
 	30,
 	SCRIPTCONFIG_NONE,
-	NULL,
+	nullptr,
 	false
 };
 
@@ -52,7 +52,7 @@ AIConfig::AIConfig(const AIConfig *config) : ScriptConfig(config)
 	} else {
 		config = &_settings_game.ai_config[company];
 	}
-	if (*config == NULL) *config = new AIConfig();
+	if (*config == nullptr) *config = new AIConfig();
 	return *config;
 }
 
@@ -69,7 +69,7 @@ ScriptInfo *AIConfig::FindInfo(const char *name, int version, bool force_exact_m
 bool AIConfig::ResetInfo(bool force_exact_match)
 {
 	this->info = (ScriptInfo *)AI::FindInfo(this->name, force_exact_match ? this->version : -1, force_exact_match);
-	return this->info != NULL;
+	return this->info != nullptr;
 }
 
 void AIConfig::PushExtraConfigList()
@@ -90,7 +90,7 @@ void AIConfig::ClearConfigList()
 
 int AIConfig::GetSetting(const char *name) const
 {
-	if (this->info == NULL) {
+	if (this->info == nullptr) {
 		SettingValueList::const_iterator it = this->settings.find(name);
 		if (it == this->settings.end()) {
 			assert(strcmp("start_date", name) == 0);
@@ -111,7 +111,7 @@ int AIConfig::GetSetting(const char *name) const
 
 void AIConfig::SetSetting(const char *name, int value)
 {
-	if (this->info == NULL) {
+	if (this->info == nullptr) {
 		if (strcmp("start_date", name) != 0) return;
 		value = Clamp(value, AI::START_NEXT_MIN, AI::START_NEXT_MAX);
 
diff --git a/src/ai/ai_core.cpp b/src/ai/ai_core.cpp
index ff2fc286a..cc2eb42c8 100644
--- a/src/ai/ai_core.cpp
+++ b/src/ai/ai_core.cpp
@@ -26,8 +26,8 @@
 #include "../safeguards.h"
 
 /* static */ uint AI::frame_counter = 0;
-/* static */ AIScannerInfo *AI::scanner_info = NULL;
-/* static */ AIScannerLibrary *AI::scanner_library = NULL;
+/* static */ AIScannerInfo *AI::scanner_info = nullptr;
+/* static */ AIScannerLibrary *AI::scanner_library = nullptr;
 
 /* static */ bool AI::CanStartNew()
 {
@@ -44,9 +44,9 @@
 
 	AIConfig *config = AIConfig::GetConfig(company, AIConfig::SSS_FORCE_GAME);
 	AIInfo *info = config->GetInfo();
-	if (info == NULL || (rerandomise_ai && config->IsRandom())) {
+	if (info == nullptr || (rerandomise_ai && config->IsRandom())) {
 		info = AI::scanner_info->SelectRandomAI();
-		assert(info != NULL);
+		assert(info != nullptr);
 		/* Load default data and store the name in the settings */
 		config->Change(info->GetName(), -1, false, true);
 	}
@@ -56,7 +56,7 @@
 	Company *c = Company::Get(company);
 
 	c->ai_info = info;
-	assert(c->ai_instance == NULL);
+	assert(c->ai_instance == nullptr);
 	c->ai_instance = new AIInstance();
 	c->ai_instance->Initialize(info);
 
@@ -111,8 +111,8 @@
 	Company *c = Company::Get(company);
 
 	delete c->ai_instance;
-	c->ai_instance = NULL;
-	c->ai_info = NULL;
+	c->ai_instance = nullptr;
+	c->ai_info = nullptr;
 
 	cur_company.Restore();
 
@@ -164,10 +164,10 @@
 
 /* static */ void AI::Initialize()
 {
-	if (AI::scanner_info != NULL) AI::Uninitialize(true);
+	if (AI::scanner_info != nullptr) AI::Uninitialize(true);
 
 	AI::frame_counter = 0;
-	if (AI::scanner_info == NULL) {
+	if (AI::scanner_info == nullptr) {
 		TarScanner::DoScan(TarScanner::AI);
 		AI::scanner_info = new AIScannerInfo();
 		AI::scanner_info->Initialize();
@@ -187,17 +187,17 @@
 	} else {
 		delete AI::scanner_info;
 		delete AI::scanner_library;
-		AI::scanner_info = NULL;
-		AI::scanner_library = NULL;
+		AI::scanner_info = nullptr;
+		AI::scanner_library = nullptr;
 
 		for (CompanyID c = COMPANY_FIRST; c < MAX_COMPANIES; c++) {
-			if (_settings_game.ai_config[c] != NULL) {
+			if (_settings_game.ai_config[c] != nullptr) {
 				delete _settings_game.ai_config[c];
-				_settings_game.ai_config[c] = NULL;
+				_settings_game.ai_config[c] = nullptr;
 			}
-			if (_settings_newgame.ai_config[c] != NULL) {
+			if (_settings_newgame.ai_config[c] != nullptr) {
 				delete _settings_newgame.ai_config[c];
-				_settings_newgame.ai_config[c] = NULL;
+				_settings_newgame.ai_config[c] = nullptr;
 			}
 		}
 	}
@@ -209,10 +209,10 @@
 	 *  the AIConfig. If not, remove the AI from the list (which will assign
 	 *  a random new AI on reload). */
 	for (CompanyID c = COMPANY_FIRST; c < MAX_COMPANIES; c++) {
-		if (_settings_game.ai_config[c] != NULL && _settings_game.ai_config[c]->HasScript()) {
+		if (_settings_game.ai_config[c] != nullptr && _settings_game.ai_config[c]->HasScript()) {
 			if (!_settings_game.ai_config[c]->ResetInfo(true)) {
 				DEBUG(script, 0, "After a reload, the AI by the name '%s' was no longer found, and removed from the list.", _settings_game.ai_config[c]->GetName());
-				_settings_game.ai_config[c]->Change(NULL);
+				_settings_game.ai_config[c]->Change(nullptr);
 				if (Company::IsValidAiID(c)) {
 					/* The code belonging to an already running AI was deleted. We can only do
 					 * one thing here to keep everything sane and that is kill the AI. After
@@ -226,10 +226,10 @@
 				Company::Get(c)->ai_info = _settings_game.ai_config[c]->GetInfo();
 			}
 		}
-		if (_settings_newgame.ai_config[c] != NULL && _settings_newgame.ai_config[c]->HasScript()) {
+		if (_settings_newgame.ai_config[c] != nullptr && _settings_newgame.ai_config[c]->HasScript()) {
 			if (!_settings_newgame.ai_config[c]->ResetInfo(false)) {
 				DEBUG(script, 0, "After a reload, the AI by the name '%s' was no longer found, and removed from the list.", _settings_newgame.ai_config[c]->GetName());
-				_settings_newgame.ai_config[c]->Change(NULL);
+				_settings_newgame.ai_config[c]->Change(nullptr);
 			}
 		}
 	}
@@ -283,7 +283,7 @@
 {
 	if (!_networking || _network_server) {
 		Company *c = Company::GetIfValid(company);
-		assert(c != NULL && c->ai_instance != NULL);
+		assert(c != nullptr && c->ai_instance != nullptr);
 
 		Backup<CompanyByte> cur_company(_current_company, company, FILE_LINE);
 		c->ai_instance->Save();
@@ -297,7 +297,7 @@
 {
 	if (!_networking || _network_server) {
 		Company *c = Company::GetIfValid(company);
-		assert(c != NULL && c->ai_instance != NULL);
+		assert(c != nullptr && c->ai_instance != nullptr);
 
 		Backup<CompanyByte> cur_company(_current_company, company, FILE_LINE);
 		c->ai_instance->Load(version);
diff --git a/src/ai/ai_gui.cpp b/src/ai/ai_gui.cpp
index eaf2a9d83..4932c0f61 100644
--- a/src/ai/ai_gui.cpp
+++ b/src/ai/ai_gui.cpp
@@ -139,13 +139,13 @@ struct AIListWindow : public Window {
 				break;
 			}
 			case WID_AIL_INFO_BG: {
-				AIInfo *selected_info = NULL;
+				AIInfo *selected_info = nullptr;
 				ScriptInfoList::const_iterator it = this->info_list->begin();
-				for (int i = 1; selected_info == NULL && it != this->info_list->end(); i++, it++) {
+				for (int i = 1; selected_info == nullptr && it != this->info_list->end(); i++, it++) {
 					if (this->selected == i - 1) selected_info = static_cast<AIInfo *>((*it).second);
 				}
 				/* Some info about the currently selected AI. */
-				if (selected_info != NULL) {
+				if (selected_info != nullptr) {
 					int y = r.top + WD_FRAMERECT_TOP;
 					SetDParamStr(0, selected_info->GetAuthor());
 					DrawString(r.left + WD_FRAMETEXT_LEFT, r.right - WD_FRAMETEXT_RIGHT, y, STR_AI_LIST_AUTHOR);
@@ -153,7 +153,7 @@ struct AIListWindow : public Window {
 					SetDParam(0, selected_info->GetVersion());
 					DrawString(r.left + WD_FRAMETEXT_LEFT, r.right - WD_FRAMETEXT_RIGHT, y, STR_AI_LIST_VERSION);
 					y += FONT_HEIGHT_NORMAL + WD_PAR_VSEP_NORMAL;
-					if (selected_info->GetURL() != NULL) {
+					if (selected_info->GetURL() != nullptr) {
 						SetDParamStr(0, selected_info->GetURL());
 						DrawString(r.left + WD_FRAMETEXT_LEFT, r.right - WD_FRAMETEXT_RIGHT, y, STR_AI_LIST_URL);
 						y += FONT_HEIGHT_NORMAL + WD_PAR_VSEP_NORMAL;
@@ -172,7 +172,7 @@ struct AIListWindow : public Window {
 	void ChangeAI()
 	{
 		if (this->selected == -1) {
-			GetConfig(slot)->Change(NULL);
+			GetConfig(slot)->Change(nullptr);
 		} else {
 			ScriptInfoList::const_iterator it = this->info_list->begin();
 			for (int i = 0; i < this->selected; i++) it++;
@@ -407,7 +407,7 @@ struct AISettingsWindow : public Window {
 				} else {
 					DrawArrowButtons(buttons_left, y + button_y_offset, COLOUR_YELLOW, (this->clicked_button == i) ? 1 + (this->clicked_increase != rtl) : 0, editable && current_value > config_item.min_value, editable && current_value < config_item.max_value);
 				}
-				if (config_item.labels != NULL && config_item.labels->Contains(current_value)) {
+				if (config_item.labels != nullptr && config_item.labels->Contains(current_value)) {
 					SetDParam(idx++, STR_JUST_RAW_STRING);
 					SetDParamStr(idx++, config_item.labels->Find(current_value)->second);
 				} else {
@@ -805,7 +805,7 @@ struct AIConfigWindow : public Window {
 	 */
 	static bool IsEditable(CompanyID slot)
 	{
-		if (slot == OWNER_DEITY) return _game_mode != GM_NORMAL || Game::GetInstance() != NULL;
+		if (slot == OWNER_DEITY) return _game_mode != GM_NORMAL || Game::GetInstance() != nullptr;
 
 		if (_game_mode != GM_NORMAL) {
 			return slot > 0 && slot <= GetGameSettings().difficulty.max_no_competitors;
@@ -825,7 +825,7 @@ struct AIConfigWindow : public Window {
 			case WID_AIC_GAMELIST: {
 				StringID text = STR_AI_CONFIG_NONE;
 
-				if (GameConfig::GetConfig()->GetInfo() != NULL) {
+				if (GameConfig::GetConfig()->GetInfo() != nullptr) {
 					SetDParamStr(0, GameConfig::GetConfig()->GetInfo()->GetName());
 					text = STR_JUST_RAW_STRING;
 				}
@@ -843,7 +843,7 @@ struct AIConfigWindow : public Window {
 
 					if ((_game_mode != GM_NORMAL && i == 0) || (_game_mode == GM_NORMAL && Company::IsValidHumanID(i))) {
 						text = STR_AI_CONFIG_HUMAN_PLAYER;
-					} else if (AIConfig::GetConfig((CompanyID)i)->GetInfo() != NULL) {
+					} else if (AIConfig::GetConfig((CompanyID)i)->GetInfo() != nullptr) {
 						SetDParamStr(0, AIConfig::GetConfig((CompanyID)i)->GetInfo()->GetName());
 						text = STR_JUST_RAW_STRING;
 					} else {
@@ -861,7 +861,7 @@ struct AIConfigWindow : public Window {
 	void OnClick(Point pt, int widget, int click_count) override
 	{
 		if (widget >= WID_AIC_TEXTFILE && widget < WID_AIC_TEXTFILE + TFT_END) {
-			if (this->selected_slot == INVALID_COMPANY || GetConfig(this->selected_slot) == NULL) return;
+			if (this->selected_slot == INVALID_COMPANY || GetConfig(this->selected_slot) == nullptr) return;
 
 			ShowScriptTextfileWindow((TextfileType)(widget - WID_AIC_TEXTFILE), this->selected_slot);
 			return;
@@ -928,7 +928,7 @@ struct AIConfigWindow : public Window {
 				if (!_network_available) {
 					ShowErrorMessage(STR_NETWORK_ERROR_NOTAVAILABLE, INVALID_STRING_ID, WL_ERROR);
 				} else {
-					ShowNetworkContentListWindow(NULL, CONTENT_TYPE_AI, CONTENT_TYPE_GAME);
+					ShowNetworkContentListWindow(nullptr, CONTENT_TYPE_AI, CONTENT_TYPE_GAME);
 				}
 				break;
 		}
@@ -955,7 +955,7 @@ struct AIConfigWindow : public Window {
 		this->SetWidgetDisabledState(WID_AIC_MOVE_DOWN, this->selected_slot == OWNER_DEITY || this->selected_slot == INVALID_COMPANY || !IsEditable((CompanyID)(this->selected_slot + 1)));
 
 		for (TextfileType tft = TFT_BEGIN; tft < TFT_END; tft++) {
-			this->SetWidgetDisabledState(WID_AIC_TEXTFILE + tft, this->selected_slot == INVALID_COMPANY || (GetConfig(this->selected_slot)->GetTextfile(tft, this->selected_slot) == NULL));
+			this->SetWidgetDisabledState(WID_AIC_TEXTFILE + tft, this->selected_slot == INVALID_COMPANY || (GetConfig(this->selected_slot)->GetTextfile(tft, this->selected_slot) == nullptr));
 		}
 	}
 };
@@ -1024,7 +1024,7 @@ struct AIDebugWindow : public Window {
 	{
 		if (ai_debug_company == OWNER_DEITY) {
 			GameInstance *game = Game::GetInstance();
-			return game == NULL || game->IsDead();
+			return game == nullptr || game->IsDead();
 		}
 		return !Company::IsValidAiID(ai_debug_company) || Company::Get(ai_debug_company)->ai_instance->IsDead();
 	}
@@ -1038,7 +1038,7 @@ struct AIDebugWindow : public Window {
 	{
 		switch (company) {
 			case INVALID_COMPANY: return false;
-			case OWNER_DEITY:     return Game::GetInstance() != NULL;
+			case OWNER_DEITY:     return Game::GetInstance() != nullptr;
 			default:              return Company::IsValidAiID(company);
 		}
 	}
@@ -1063,7 +1063,7 @@ struct AIDebugWindow : public Window {
 		}
 
 		/* If no AI is available, see if there is a game script. */
-		if (Game::GetInstance() != NULL) ChangeToAI(OWNER_DEITY);
+		if (Game::GetInstance() != nullptr) ChangeToAI(OWNER_DEITY);
 	}
 
 	/**
@@ -1140,7 +1140,7 @@ struct AIDebugWindow : public Window {
 
 		/* Set button colour for Game Script. */
 		GameInstance *game = Game::GetInstance();
-		bool valid = game != NULL;
+		bool valid = game != nullptr;
 		bool dead = valid && game->IsDead();
 		bool paused = valid && game->IsPaused();
 
@@ -1154,7 +1154,7 @@ struct AIDebugWindow : public Window {
 
 		ScriptLog::LogData *log = this->GetLogPointer();
 
-		int scroll_count = (log == NULL) ? 0 : log->used;
+		int scroll_count = (log == nullptr) ? 0 : log->used;
 		if (this->vscroll->GetCount() != scroll_count) {
 			this->vscroll->SetCount(scroll_count);
 
@@ -1162,7 +1162,7 @@ struct AIDebugWindow : public Window {
 			this->SetWidgetDirty(WID_AID_SCROLLBAR);
 		}
 
-		if (log == NULL) return;
+		if (log == nullptr) return;
 
 		/* Detect when the user scrolls the window. Enable autoscroll when the
 		 * bottom-most line becomes visible. */
@@ -1188,7 +1188,7 @@ struct AIDebugWindow : public Window {
 			case WID_AID_NAME_TEXT:
 				if (ai_debug_company == OWNER_DEITY) {
 					const GameInfo *info = Game::GetInfo();
-					assert(info != NULL);
+					assert(info != nullptr);
 					SetDParam(0, STR_AI_DEBUG_NAME_AND_VERSION);
 					SetDParamStr(1, info->GetName());
 					SetDParam(2, info->GetVersion());
@@ -1196,7 +1196,7 @@ struct AIDebugWindow : public Window {
 					SetDParam(0, STR_EMPTY);
 				} else {
 					const AIInfo *info = Company::Get(ai_debug_company)->ai_info;
-					assert(info != NULL);
+					assert(info != nullptr);
 					SetDParam(0, STR_AI_DEBUG_NAME_AND_VERSION);
 					SetDParamStr(1, info->GetName());
 					SetDParam(2, info->GetVersion());
@@ -1212,12 +1212,12 @@ struct AIDebugWindow : public Window {
 		switch (widget) {
 			case WID_AID_LOG_PANEL: {
 				ScriptLog::LogData *log = this->GetLogPointer();
-				if (log == NULL) return;
+				if (log == nullptr) return;
 
 				int y = this->top_offset;
 				for (int i = this->vscroll->GetPosition(); this->vscroll->IsVisible(i) && i < log->used; i++) {
 					int pos = (i + log->pos + 1 - log->used + log->count) % log->count;
-					if (log->lines[pos] == NULL) break;
+					if (log->lines[pos] == nullptr) break;
 
 					TextColour colour;
 					switch (log->type[pos]) {
@@ -1357,7 +1357,7 @@ struct AIDebugWindow : public Window {
 			/* Get the log instance of the active company */
 			ScriptLog::LogData *log = this->GetLogPointer();
 
-			if (log != NULL) {
+			if (log != nullptr) {
 				this->break_string_filter.ResetState();
 				this->break_string_filter.AddLine(log->lines[log->pos]);
 				if (this->break_string_filter.GetState()) {
@@ -1385,8 +1385,8 @@ struct AIDebugWindow : public Window {
 
 		this->SelectValidDebugCompany();
 
-		ScriptLog::LogData *log = ai_debug_company != INVALID_COMPANY ? this->GetLogPointer() : NULL;
-		this->vscroll->SetCount((log == NULL) ? 0 : log->used);
+		ScriptLog::LogData *log = ai_debug_company != INVALID_COMPANY ? this->GetLogPointer() : nullptr;
+		this->vscroll->SetCount((log == nullptr) ? 0 : log->used);
 
 		/* Update company buttons */
 		for (CompanyID i = COMPANY_FIRST; i < MAX_COMPANIES; i++) {
@@ -1394,7 +1394,7 @@ struct AIDebugWindow : public Window {
 			this->SetWidgetLoweredState(i + WID_AID_COMPANY_BUTTON_START, ai_debug_company == i);
 		}
 
-		this->SetWidgetDisabledState(WID_AID_SCRIPT_GAME, Game::GetGameInstance() == NULL);
+		this->SetWidgetDisabledState(WID_AID_SCRIPT_GAME, Game::GetGameInstance() == nullptr);
 		this->SetWidgetLoweredState(WID_AID_SCRIPT_GAME, ai_debug_company == OWNER_DEITY);
 
 		this->SetWidgetLoweredState(WID_AID_BREAK_STR_ON_OFF_BTN, this->break_check_enabled);
@@ -1437,7 +1437,7 @@ static EventState AIDebugGlobalHotkeys(int hotkey)
 {
 	if (_game_mode != GM_NORMAL) return ES_NOT_HANDLED;
 	Window *w = ShowAIDebugWindow(INVALID_COMPANY);
-	if (w == NULL) return ES_NOT_HANDLED;
+	if (w == nullptr) return ES_NOT_HANDLED;
 	return w->OnHotkey(hotkey);
 }
 
@@ -1530,14 +1530,14 @@ Window *ShowAIDebugWindow(CompanyID show_company)
 {
 	if (!_networking || _network_server) {
 		AIDebugWindow *w = (AIDebugWindow *)BringWindowToFrontById(WC_AI_DEBUG, 0);
-		if (w == NULL) w = new AIDebugWindow(&_ai_debug_desc, 0);
+		if (w == nullptr) w = new AIDebugWindow(&_ai_debug_desc, 0);
 		if (show_company != INVALID_COMPANY) w->ChangeToAI(show_company);
 		return w;
 	} else {
 		ShowErrorMessage(STR_ERROR_AI_DEBUG_SERVER_ONLY, INVALID_STRING_ID, WL_INFO);
 	}
 
-	return NULL;
+	return nullptr;
 }
 
 /**
@@ -1563,7 +1563,7 @@ void ShowAIDebugWindowIfAIError()
 	}
 
 	GameInstance *g = Game::GetGameInstance();
-	if (g != NULL && g->IsDead()) {
+	if (g != nullptr && g->IsDead()) {
 		ShowAIDebugWindow(OWNER_DEITY);
 	}
 }
diff --git a/src/ai/ai_info.cpp b/src/ai/ai_info.cpp
index 62ddb2344..af7ae5729 100644
--- a/src/ai/ai_info.cpp
+++ b/src/ai/ai_info.cpp
@@ -65,8 +65,8 @@ template <> const char *GetClassName<AIInfo, ST_AI>() { return "AIInfo"; }
 /* static */ SQInteger AIInfo::Constructor(HSQUIRRELVM vm)
 {
 	/* Get the AIInfo */
-	SQUserPointer instance = NULL;
-	if (SQ_FAILED(sq_getinstanceup(vm, 2, &instance, 0)) || instance == NULL) return sq_throwerror(vm, "Pass an instance of a child class of AIInfo to RegisterAI");
+	SQUserPointer instance = nullptr;
+	if (SQ_FAILED(sq_getinstanceup(vm, 2, &instance, 0)) || instance == nullptr) return sq_throwerror(vm, "Pass an instance of a child class of AIInfo to RegisterAI");
 	AIInfo *info = (AIInfo *)instance;
 
 	SQInteger res = ScriptInfo::Constructor(vm, info);
@@ -100,7 +100,7 @@ template <> const char *GetClassName<AIInfo, ST_AI>() { return "AIInfo"; }
 	}
 
 	/* Remove the link to the real instance, else it might get deleted by RegisterAI() */
-	sq_setinstanceup(vm, 2, NULL);
+	sq_setinstanceup(vm, 2, nullptr);
 	/* Register the AI to the base system */
 	info->GetScanner()->RegisterScript(info);
 	return 0;
@@ -112,7 +112,7 @@ template <> const char *GetClassName<AIInfo, ST_AI>() { return "AIInfo"; }
 	SQUserPointer instance;
 	sq_getinstanceup(vm, 2, &instance, 0);
 	AIInfo *info = (AIInfo *)instance;
-	info->api_version = NULL;
+	info->api_version = nullptr;
 
 	SQInteger res = ScriptInfo::Constructor(vm, info);
 	if (res != 0) return res;
@@ -122,7 +122,7 @@ template <> const char *GetClassName<AIInfo, ST_AI>() { return "AIInfo"; }
 	info->api_version = stredup(buf);
 
 	/* Remove the link to the real instance, else it might get deleted by RegisterAI() */
-	sq_setinstanceup(vm, 2, NULL);
+	sq_setinstanceup(vm, 2, nullptr);
 	/* Register the AI to the base system */
 	static_cast<AIScannerInfo *>(info->GetScanner())->SetDummyAI(info);
 	return 0;
@@ -131,7 +131,7 @@ template <> const char *GetClassName<AIInfo, ST_AI>() { return "AIInfo"; }
 AIInfo::AIInfo() :
 	min_loadable_version(0),
 	use_as_random(false),
-	api_version(NULL)
+	api_version(nullptr)
 {
 }
 
diff --git a/src/ai/ai_info.hpp b/src/ai/ai_info.hpp
index 51cfb7d8a..ddf1edc6c 100644
--- a/src/ai/ai_info.hpp
+++ b/src/ai/ai_info.hpp
@@ -59,7 +59,7 @@ private:
 /** All static information from an AI library like name, version, etc. */
 class AILibrary : public ScriptInfo {
 public:
-	AILibrary() : ScriptInfo(), category(NULL) {};
+	AILibrary() : ScriptInfo(), category(nullptr) {};
 	~AILibrary();
 
 	/**
diff --git a/src/ai/ai_instance.cpp b/src/ai/ai_instance.cpp
index c03e74599..f5f5904c0 100644
--- a/src/ai/ai_instance.cpp
+++ b/src/ai/ai_instance.cpp
@@ -216,10 +216,10 @@ void AIInstance::Died()
 	ShowAIDebugWindow(_current_company);
 
 	const AIInfo *info = AIConfig::GetConfig(_current_company, AIConfig::SSS_FORCE_GAME)->GetInfo();
-	if (info != NULL) {
+	if (info != nullptr) {
 		ShowErrorMessage(STR_ERROR_AI_PLEASE_REPORT_CRASH, INVALID_STRING_ID, WL_WARNING);
 
-		if (info->GetURL() != NULL) {
+		if (info->GetURL() != nullptr) {
 			ScriptLog::Info("Please report the error to the following URL:");
 			ScriptLog::Info(info->GetURL());
 		}
@@ -258,7 +258,7 @@ void CcAI(const CommandCost &result, TileIndex tile, uint32 p1, uint32 p2)
 	 * when the company does not exist anymore.
 	 */
 	const Company *c = Company::GetIfValid(_current_company);
-	if (c == NULL || c->ai_instance == NULL) return;
+	if (c == nullptr || c->ai_instance == nullptr) return;
 
 	c->ai_instance->DoCommandCallback(result, tile, p1, p2);
 	c->ai_instance->Continue();
diff --git a/src/ai/ai_scanner.cpp b/src/ai/ai_scanner.cpp
index 5f16de3f9..1d0fed188 100644
--- a/src/ai/ai_scanner.cpp
+++ b/src/ai/ai_scanner.cpp
@@ -23,7 +23,7 @@
 
 AIScannerInfo::AIScannerInfo() :
 	ScriptScanner(),
-	info_dummy(NULL)
+	info_dummy(nullptr)
 {
 }
 
@@ -94,14 +94,14 @@ AIInfo *AIScannerInfo::SelectRandomAI() const
 
 AIInfo *AIScannerInfo::FindInfo(const char *nameParam, int versionParam, bool force_exact_match)
 {
-	if (this->info_list.size() == 0) return NULL;
-	if (nameParam == NULL) return NULL;
+	if (this->info_list.size() == 0) return nullptr;
+	if (nameParam == nullptr) return nullptr;
 
 	char ai_name[1024];
 	strecpy(ai_name, nameParam, lastof(ai_name));
 	strtolower(ai_name);
 
-	AIInfo *info = NULL;
+	AIInfo *info = nullptr;
 	int version = -1;
 
 	if (versionParam == -1) {
@@ -110,7 +110,7 @@ AIInfo *AIScannerInfo::FindInfo(const char *nameParam, int versionParam, bool fo
 
 		/* If we didn't find a match AI, maybe the user included a version */
 		char *e = strrchr(ai_name, '.');
-		if (e == NULL) return NULL;
+		if (e == nullptr) return nullptr;
 		*e = '\0';
 		e++;
 		versionParam = atoi(e);
@@ -165,7 +165,7 @@ AILibrary *AIScannerLibrary::FindLibrary(const char *library, int version)
 
 	/* Check if the library + version exists */
 	ScriptInfoList::iterator iter = this->info_list.find(library_name);
-	if (iter == this->info_list.end()) return NULL;
+	if (iter == this->info_list.end()) return nullptr;
 
 	return static_cast<AILibrary *>((*iter).second);
 }
diff --git a/src/ai/ai_scanner.hpp b/src/ai/ai_scanner.hpp
index dafc340be..2e0532d00 100644
--- a/src/ai/ai_scanner.hpp
+++ b/src/ai/ai_scanner.hpp
@@ -32,7 +32,7 @@ public:
 	 * @param nameParam The name of the AI.
 	 * @param versionParam The version of the AI, or -1 if you want the latest.
 	 * @param force_exact_match Only match name+version, never latest.
-	 * @return NULL if no match found, otherwise the AI that matched.
+	 * @return nullptr if no match found, otherwise the AI that matched.
 	 */
 	class AIInfo *FindInfo(const char *nameParam, int versionParam, bool force_exact_match);
 
@@ -60,7 +60,7 @@ public:
 	 * Find a library in the pool.
 	 * @param library The library name to find.
 	 * @param version The version the library should have.
-	 * @return The library if found, NULL otherwise.
+	 * @return The library if found, nullptr otherwise.
 	 */
 	class AILibrary *FindLibrary(const char *library, int version);