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c++ Programming Glossary: caWhy does changing `const ull` to `const ull&` in function parameter result in performance gain? http://stackoverflow.com/questions/14805641/why-does-changing-const-ull-to-const-ull-in-function-parameter-result-in-pe when compiled with gcc 4.7.2 and flags O3 std c 11 g and I can't figure out why this would make such a big difference. static.. std vector ull const_iterator rend const ull x ull tmp 0 carry 0 i 0 for auto rhs_it rbegin rhs_it rend rhs_it tmp x rhs_it.. auto rhs_it rbegin rhs_it rend rhs_it tmp x rhs_it data i carry if tmp imax carry tmp numbits tmp imax 1 else carry..
Algorithm to generate all permutation by selecting some or all charaters http://stackoverflow.com/questions/3844721/algorithm-to-generate-all-permutation-by-selecting-some-or-all-charaters Like if my string is abc output would be a b c ab ba ac ca bc cb abc acb bac bca cab cba . I thought a basic algorithm.. abc output would be a b c ab ba ac ca bc cb abc acb bac bca cab cba . I thought a basic algorithm in which I generate all.. output would be a b c ab ba ac ca bc cb abc acb bac bca cab cba . I thought a basic algorithm in which I generate all possible..
Speed of accessing local vs. global variables in gcc/g++ at different optimization levels http://stackoverflow.com/questions/7241035/speed-of-accessing-local-vs-global-variables-in-gcc-g-at-different-optimizati of accessing local vs. global variables in gcc g at different optimization levels.. in gcc give quite different results when accessing a local or a global variable in a loop. The reason this surprised me.. come two examples in C but their C counterparts give practically the same timings global 0 for int i 0 i SIZE i global which..
http://stackoverflow.com/questions/929495/why-is-mingw-very-slow minGW on Windows and I'm trying to build a wxWidgets application which has ca. 20k lines and 40 source modules. And it builds.. and I'm trying to build a wxWidgets application which has ca. 20k lines and 40 source modules. And it builds very very slow... a portable code this code on Linux compiles very fast. I can't follow the build message window... The entire process lasts..
http://stackoverflow.com/questions/9429491/how-are-gcc-g-bootstrapped others when it was written. The very first C compiler ever ca. 1973 IIRC was implemented in PDP 11 assembly. Similarly the.. the one you just built optional repeat step 2 for verification purposes. This process is called bootstrapping . It tests.. repeat step 2 for verification purposes. This process is called bootstrapping . It tests the compiler's capability of compiling..
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