corrections adjustments motivated by first real review of the library

examples/example1.cpp

@@ -3,23 +3,22 @@
 #include <iostream>
 
 #include "../include/safe_integer.hpp"
-//#include "../include/safe_compare.hpp"
 
 void detected_msg(bool detected){
     std::cout << (detected ? "error detected!" : "error NOT detected! ") << std::endl;
 }
 
 int main(int argc, const char * argv[]){
+    // problem: undetected erroneous expression evaluation
     std::cout << "example 1:";
     std::cout << "undetected erroneous expression evaluation" << std::endl;
     std::cout << "Not using safe numerics" << std::endl;
     try{
-        char x = 127;
-        char y = 2;
-        char z;
+        signed char x = 127;
+        signed char y = 2;
+        signed char z;
         // this produces an invalid result !
         z = x + y;
-        // it is the wrong result !!!
         assert(z != 129);
         // but assert fails to detect it since C++ implicitly
         // converts variables to int before evaluating he expression!
@@ -28,18 +27,18 @@ int main(int argc, const char * argv[]){
         detected_msg(false);
     }
     catch(...){
-        assert(false); // never arrive here
+        assert(false); // we never arrive here
     }
     // solution: replace char with safe<char>
     std::cout << "Using safe numerics" << std::endl;
     try{
         using namespace boost::numeric;
-        safe<char> x = 127;
-        safe<char> y = 2;
-        safe<char> z;
-        // rather than producing and invalid result an exception is thrown
+        safe<signed char> x = 127;
+        safe<signed char> y = 2;
+        safe<signed char> z;
+        // rather than producing an invalid result an exception is thrown
         z = x + y;
-        assert(false); // never arrive here
+        assert(false); // we never arrive here
     }
     catch(std::range_error & e){
         // which can catch here