system: add to_sstring()

Signed-off-by: Simon Rozman <simon@rozman.si>

include/stdex/stream.hpp

@@ -2383,6 +2383,9 @@ namespace stdex
 			socket(_In_ const socket& other);
 			socket& operator =(_In_ const socket& other);
 
+			// Force use of valid() method when testing handle.
+			operator bool() const;
+
 		public:
 			socket(_Inout_ socket&& other) noexcept : m_h(other.m_h)
 			{

include/stdex/system.hpp

@@ -75,6 +75,28 @@ namespace stdex
 	///
 	using sstring = std::basic_string<stdex::schar_t>;
 
+#ifdef UNICODE
+	inline sstring to_sstring(int value) { return std::to_wstring(value); }
+	inline sstring to_sstring(long value) { return std::to_wstring(value); }
+	inline sstring to_sstring(long long value) { return std::to_wstring(value); }
+	inline sstring to_sstring(unsigned value) { return std::to_wstring(value); }
+	inline sstring to_sstring(unsigned long value) { return std::to_wstring(value); }
+	inline sstring to_sstring(unsigned long long value) { return std::to_wstring(value); }
+	inline sstring to_sstring(float value) { return std::to_wstring(value); }
+	inline sstring to_sstring(double value) { return std::to_wstring(value); }
+	inline sstring to_sstring(long double value) { return std::to_wstring(value); }
+#else
+	inline sstring to_sstring(int value) { return std::to_string(value); }
+	inline sstring to_sstring(long value) { return std::to_string(value); }
+	inline sstring to_sstring(long long value) { return std::to_string(value); }
+	inline sstring to_sstring(unsigned value) { return std::to_string(value); }
+	inline sstring to_sstring(unsigned long value) { return std::to_string(value); }
+	inline sstring to_sstring(unsigned long long value) { return std::to_string(value); }
+	inline sstring to_sstring(float value) { return std::to_string(value); }
+	inline sstring to_sstring(double value) { return std::to_string(value); }
+	inline sstring to_sstring(long double value) { return std::to_string(value); }
+#endif
+
 	///
 	/// String for system functions for backward compatibility
 	/// Use stdex::sstring
@@ -200,6 +222,10 @@ namespace stdex
 		///
 		operator T() const noexcept { return m_h; }
 
+	private:
+		// Force use of valid() method when testing handle.
+		operator bool() const;
+
 	protected:
 		T m_h;
 	};