字符串头文件不能叫String.h，否则跟gcc内部的string.h冲突，倒置无法包含

String.cpp

@@ -5,7 +5,7 @@
 #include <math.h>
 #include <stdarg.h>
 
-#include "String.h"
+#include "SString.h"
 
 char* utohex(uint value, byte size, char* string, bool upper);
 extern char* itoa(int value, char* string, int radix);

Sys.h

@@ -41,7 +41,7 @@ void assert_failed2(const char* msg, const char* file, unsigned int line);
 #endif
 
 #include "Type.h"
-#include "String.h"
+#include "SString.h"
 
 /* 引脚定义 */
 #include "Platform\Pin.h"