「🔨」 fix: fixed some things.

ex01/RPN.cpp

@@ -15,10 +15,10 @@ typedef int (*OperatorFunctions)(int, int);
 void rpn(char *av)
 {
 	OperatorFunctions calc[128] = { NULL };
-	calc['+'] = &add;
-	calc['-'] = &subst;
-	calc['*'] = &mult;
-	calc['/'] = ÷
+	calc[(int) '+'] = &add;
+	calc[(int) '-'] = &subst;
+	calc[(int) '*'] = &mult;
+	calc[(int) '/'] = ÷
 
 	std::istringstream	ss_input((std::string(av)));
 	std::stack<int>		stack;