add exit function

 #include "EchoString.h"
 
+const std::string EchoString::mExitMessage = "exit";
+
 void EchoString::PrintScreen()
 {
 	std::cout << "Echo Program : ";
@@ -8,9 +10,9 @@ void EchoString::PrintScreen()
 
 void EchoString::InputString()
 {
-	while (getEcho().empty())
+	while (true)
 	{
-		std::cout << "Input your string : ";
+		std::cout << "Input your string(EXIT : \"exit\") : ";
 		std::getline(std::cin, mEcho);
 
 		if (std::cin.fail())
@@ -20,6 +22,8 @@ void EchoString::InputString()
 			system("cls");
 			continue;
 		}
+
+		break;
 	}
 }
 

@@ -7,6 +7,7 @@ class EchoString
 {
 private:
 	std::string mEcho;
+	static const std::string mExitMessage;
 
 public:
 	void PrintScreen();
@@ -19,6 +20,7 @@ public:
 	void setEcho(const std::string& echo) { mEcho = echo; }
 	std::string getEcho()	const { return mEcho; }
 	std::string getEcho() { return mEcho; }
+	std::string getExitMessage() { return mExitMessage; }
 
 };
 

@@ -7,8 +7,14 @@ int main()
 {
 	EchoString echo;
 
+	while (true)
+	{
 		echo.InputString();
+		if (echo.getEcho() == echo.getExitMessage())
+			break;
+
 		echo.PrintScreen();
+	}
 
 	return 0;
 }
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