UE427_Logging

UE427_Logging

UE_LOG宏会经常用到，方便地判断我们的代码何时能够起到作用。

#define UE_LOG(CategoryName, Verbosity, Format, ...)
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它的前两个参数表示日志的类别名称（可以随意命名）以及日志的级别（ELogVerbosity枚举量），之后的参数类似于经典的printf()，但是最常用的参数类型只有%d（整数），%f（浮点数）和%s（字符串，并且一定是FString类型），我们需要执行必要的转换函数将char*转换到FString再输入到日志中。

namespace ELogVerbosity
{
	enum Type : uint8;
}
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namespace ELogVerbosity
{
	enum Type : uint8
	{
		/** Not used */
		NoLogging		= 0,

		/** Always prints a fatal error to console (and log file) and crashes (even if logging is disabled) */
		Fatal,

		/** 
		 * Prints an error to console (and log file). 
		 * Commandlets and the editor collect and report errors. Error messages result in commandlet failure.
		 */
		Error,

		/** 
		 * Prints a warning to console (and log file).
		 * Commandlets and the editor collect and report warnings. Warnings can be treated as an error.
		 */
		Warning,

		/** Prints a message to console (and log file) */
		Display,

		/** Prints a message to a log file (does not print to console) */
		Log,

		/** 
		 * Prints a verbose message to a log file (if Verbose logging is enabled for the given category, 
		 * usually used for detailed logging) 
		 */
		Verbose,

		/** 
		 * Prints a verbose message to a log file (if VeryVerbose logging is enabled, 
		 * usually used for detailed logging that would otherwise spam output) 
		 */
		VeryVerbose,

		// Log masks and special Enum values

		All				= VeryVerbose,
		NumVerbosity,
		VerbosityMask	= 0xf,
		SetColor		= 0x40, // not actually a verbosity, used to set the color of an output device 
		BreakOnLog		= 0x80
	};
}
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// Log格式：
	// 1. Log Message
	//"This is a message to yourself during runtime!"
	UE_LOG(YourLog,Warning,TEXT("This is a message to yourself during runtime!"));
	// 2. Log an FString
	// %s strings are wanted as TCHAR* by Log, so use *FString() %s字符串被日志需要作为TCHAR*，所以使用*FString()
	//"MyCharacter's Name is %s"
	UE_LOG(YourLog,Warning,TEXT("MyCharacter's Name is %s"), *MyCharacter->GetName() );
	// 3. Log an Int
	//"MyCharacter's Health is %d"
	UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %d"), MyCharacter->Health );
	// 4. Log a Float
	//"MyCharacter's Health is %f"
	UE_LOG(YourLog,Warning,TEXT("MyCharacter's Health is %f"), MyCharacter->Health );
	// 5. Log an FVector
	//"MyCharacter's Location is %s"
	UE_LOG(YourLog,Warning,TEXT("MyCharacter's Location is %s"), 
	    *MyCharacter->GetActorLocation().ToString());
	// 6. Log an FName
	//"MyCharacter's FName is %s"
	UE_LOG(YourLog,Warning,TEXT("MyCharacter's FName is %s"), 
	    *MyCharacter->GetFName().ToString());
	// 7. Log an FString,Int,Float
	//"%s has health %d, which is %f percent of total health" %s的生命值%d，也就是总生命值的%f %
	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：
// 第二个参数是是用来控制颜色的。
//"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!"));
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文章参考：

Ue4的UE_LOG

https://www.cnblogs.com/blueroses/p/6037981.html
https://zhuanlan.zhihu.com/p/469324623

Logging

https://unrealcommunity.wiki/logging-lgpidy6i

官方说明（以上若不明请详看以下）

// Formatting Examples Quick Reference
// 1. Logging an FString
UE_LOG(LogTemp, Warning, TEXT("The Actor's name is %s"), *YourActor->GetName());
// 2. Logging a Bool
UE_LOG(LogTemp, Warning, TEXT("The boolean value is %s"), ( bYourBool ? TEXT("true") : TEXT("false") ));
// 3. Logging an Integer
UE_LOG(LogTemp, Warning, TEXT("The integer value is: %d"), YourInteger);
// 4. Logging a Float
UE_LOG(LogTemp, Warning, TEXT("The float value is: %f"), YourFloat);
// 5. Logging an FVector
UE_LOG(LogTemp, Warning, TEXT("The vector value is: %s"), *YourVector.ToString());
// 6. Logging with Multiple Specifiers
UE_LOG(LogTemp, Warning, TEXT("Current values are: vector %s, float %f, and integer %d"), *YourVector.ToString(), YourFloat, YourInteger);
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