---
title: UE_Log
date: 2022-08-31 09:40:26
excerpt: 
tags: 
rating: ⭐
---
说明：本文为Wiki上的RAMA大神文章的大致翻译

## 显示日志
- 在游戏模式下，你需要在游戏的快捷方式后面加 -Log，才会在游戏中显示。
- 如果想在游戏中看到，需要到Engin.ini中修改参数添加"GameCommandLine=-log，如果没有，则需要按~，输入-Log命令开启。

## QuickStart
UE_LOG(LogTemp, Warning, TEXT("Your message"));

不用设置标签，简单快速。

## CustomTag
在你的游戏头文件中进行声明：
```c++
//General Log
DECLARE_LOG_CATEGORY_EXTERN(YourLog, Log, All);

//Logging during game startup
DECLARE_LOG_CATEGORY_EXTERN(YourInit, Log, All);

//Logging for your AI system
DECLARE_LOG_CATEGORY_EXTERN(YourAI, Log, All);

//Logging for Critical Errors that must always be addressed
DECLARE_LOG_CATEGORY_EXTERN(YourCriticalErrors, Log, All);
```
这样输出的Log你就可以知道是哪个部分的，这也是UE_Log很有用的原因。

之后在你的游戏Cpp文件中定义：
```c++
//General Log
DEFINE_LOG_CATEGORY(YourLog);

//Logging during game startup
DEFINE_LOG_CATEGORY(YourInit);

//Logging for your AI system
DEFINE_LOG_CATEGORY(YourAI);

//Logging for Critical Errors that must always be addressed
DEFINE_LOG_CATEGORY(YourCriticalErrors);
```

## Log格式化
### Log Message
```c++
//"This is a message to yourself during runtime!"
UE_LOG(YourLog,Warning,TEXT("This is a message to yourself during runtime!"));
```

### Log an FString
```c++
 %s strings are wanted as TCHAR* by Log, so use *FString()
//"MyCharacter's Name is %s"
UE_LOG(YourLog,Warning,TEXT("MyCharacter's Name is %s"), *MyCharacter->GetName() );
```

### Log an Int
```c++
//"MyCharacter's Health is %d"
UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %d"), MyCharacter->Health );
```

### Log a Float
```c++
//"MyCharacter's Health is %f"
UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %f"), MyCharacter->Health );
```

### Log an FVector
```c++
//"MyCharacter's Location is %s"
UE_LOG(YourLog,Warning,TEXT("MyCharacter's Location is %s"),
    *MyCharacter->GetActorLocation().ToString());
```

### Log an FName
```c++
//"MyCharacter's FName is %s"
UE_LOG(YourLog,Warning,TEXT("MyCharacter's FName is %s"),
    *MyCharacter->GetFName().ToString());
```

### Log an FString,Int,Float
```c++
//"%s has health %d, which is %f percent of total health"
UE_LOG(YourLog,Warning,TEXT("%s has health %d, which is %f percent of total health"),
    *MyCharacter->GetName(), MyCharacter->Health, MyCharacter->HealthPercent);
```

## Log的颜色设置
```c++
//"this is Grey Text"
UE_LOG(YourLog,Log,TEXT("This is grey text!"));

//"this is Yellow Text"
UE_LOG(YourLog,Warning,TEXT("This is yellow text!"));

//"This is Red Text"
UE_LOG(YourLog,Error,TEXT("This is red text!"));
```

可以看得出第二个参数是是用来控制颜色的。

## 向客户端传递信息（网络模式）：
```c++
PlayerController->ClientMessage("Your Message");
```

命令行命令以及Engine.ini配置：
Log conventions (in the console, ini files, or environment variables)

[cat] = a category for the command to operate on, or 'global' for all categories.
标签，没有设置就显示所有的Log

[level] = verbosity level, one of: none, error, warning, display, log, verbose, all, default
关卡，显示某某关卡的Log

At boot time, compiled in default is overridden by ini files setting, which is overridden by command line

Log console command usage

Log list - list all log categories

Log list [string] - list all log categories containing a substring

Log reset - reset all log categories to their boot-time default

Log [cat] - toggle the display of the category [cat]

Log [cat] off - disable display of the category [cat]

Log [cat] on - resume display of the category [cat]

Log [cat] [level] - set the verbosity level of the category [cat]

Log [cat] break - toggle the debug break on display of the category [cat]

### Log command line
- LogCmds=\"[arguments],[arguments]...\"           - applies a list of console commands at boot time
- LogCmds=\"foo verbose, bar off\"         - turns on the foo category and turns off the bar category

### Environment variables
Any command line option can be set via the environment variable UE-CmdLineArgs

set UE-CmdLineArgs=\"-LogCmds=foo verbose breakon, bar off\"

### Config file
In DefaultEngine.ini or Engine.ini:  
```ini
[Core.Log]
global=[default verbosity for things not listed later]
[cat]=[level]
foo=verbose break
```

## 其他
Rama后面的一篇文章提供了显示代码行号、函数名称、类名等功能：
https://wiki.unrealengine.com/Logs,_Printing_the_Class_Name,_Function_Name,_Line_Number_of_your_Calling_Code!