first version with working policies

promotion pollicy
exception policy
improved documentation

examples/example5.cpp

@@ -0,0 +1,40 @@
+#include <cassert>
+#include <stdexcept>
+#include <iostream>
+
+#include "../include/safe_range.hpp"
+
+void detected_msg(bool detected){
+    std::cout << (detected ? "error detected!" : "error NOT detected! ") << std::endl;
+}
+
+int main(int argc, const char * argv[]){
+    // problem: array index values can exceed array bounds
+    std::cout << "example 5: ";
+    std::cout << "array index values can exceed array bounds" << std::endl;
+    std::cout << "Not using safe numerics" << std::endl;
+    int i_array[37];
+
+    unsigned int i_index = 43;
+    // the following corrupts memory.
+    // This may or may not be detected at run time.
+    // i_array[i_index] = 84; // comment this out so it can be tested!
+    detected_msg(false);
+
+    // solution: replace unsigned array index with safe_unsigned_range
+    std::cout << "Using safe numerics" << std::endl;
+    try{
+        using namespace boost::numeric;
+        safe_unsigned_range<0, sizeof(i_array)/sizeof(int) - 1> i_index;
+        i_index = 36; // this works fine
+        i_array[i_index] = 84;
+        i_index = 37; // throw exception here!
+        i_array[i_index] = 84; // so we never arrive here
+        assert(false);
+    }
+    catch(std::range_error & e){
+        std::cout << e.what() << std::endl;
+        detected_msg(true);
+    }
+    return 0;
+}