Ichthyostega
71aacc7698
Contrary to the built-in division operator, this function always truncates towards the next smaller integer (also for negative numbers)
104 lines
2.5 KiB
C++
104 lines
2.5 KiB
C++
/* try.cpp - for trying out some language features....
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* scons will create the binary bin/try
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*
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*/
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// 8/07 - how to control NOBUG??
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// execute with NOBUG_LOG='ttt:TRACE' bin/try
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// 1/08 - working out a static initialisation problem for Visitor (Tag creation)
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// 1/08 - check 64bit longs
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// 4/08 - comparison operators on shared_ptr<Asset>
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// 4/08 - conversions on the value_type used for boost::any
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// 5/08 - how to guard a downcasting access, so it is compiled in only if the involved types are convertible
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// 7/08 - combining partial specialisation and subclasses
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// 10/8 - abusing the STL containers to hold noncopyable values
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// 6/09 - investigating how to build a mixin template providing an operator bool()
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// 12/9 - tracking down a strange "warning: type qualifiers ignored on function return type"
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// 1/10 - can we determine at compile time the presence of a certain function (for duck-typing)?
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// 4/10 - pretty printing STL containers with python enabled GDB?
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// 1/11 - exploring numeric limits
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//#include <nobug.h>
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#include <iostream>
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//#include <typeinfo>
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#include <string>
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//#include <cstdlib>
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#include <limits>
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#include <cmath>
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#include <boost/format.hpp>
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using boost::format;
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//using std::rand;
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using std::string;
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using std::cout;
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using std::endl;
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long
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floordiv (long num, long den)
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{
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if (0 < (num^den))
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return num/den;
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else
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{
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ldiv_t res = ldiv(num,den);
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return (res.rem)? res.quot-1
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: res.quot;
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}
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}
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long
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floordiv2 (long num, long den)
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{
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ldiv_t res = ldiv(num,den);
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return (0 >= res.quot && res.rem)? res.quot-1
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: res.quot;
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}
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void
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checkDiv(int lhs, int rhs)
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{
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cout << format ("%f / %f = %f \tfloor=%f floordiv=%f \n") % lhs % rhs % (lhs / rhs) % floor(double(lhs)/rhs) % floordiv2(lhs,rhs);
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}
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int
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main (int, char**)
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{
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// NOBUG_INIT;
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checkDiv (8,4);
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checkDiv (9,4);
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checkDiv (-8,4);
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checkDiv (-9,4);
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checkDiv (8,-4);
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checkDiv (9,-4);
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checkDiv (-8,-4);
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checkDiv (-9,-4);
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checkDiv (0,4);
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checkDiv (0,-4);
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checkDiv (1,4);
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checkDiv (1,-4);
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checkDiv (-1,4);
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checkDiv (-1,-4);
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int64_t muks = std::numeric_limits<int64_t>::max();
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muks /= 30;
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double murks(muks);
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cout << format("%f // %f || %g \n") % muks % murks % std::numeric_limits<double>::epsilon();
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int64_t glucks = murks;
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cout << glucks <<endl;
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cout << "\n.gulp.\n";
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return 0;
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}
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