Why is there a significant difference in this C++ for loop’s execution time? [duplicate]

It’s an issue of memory cache. matrix[i][j] has better cache hits than matrix[j][i], since matrix[i][j] has more continuous memory accessing chances. For example, when we access matrix[i][0], the cache may load a continuous segment of memory containing matrix[i][0], thus, accessing matrix[i][1], matrix[i][2], …, will benefit from caching speed, since matrix[i][1], matrix[i][2], … are near to …

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Breaking the nested loop [duplicate]

Unlike other languages such as C/C++, in PHP you can use the optional param of break like this: break 2; In this case if you have two loops such that: while(…) { while(…) { // do // something break 2; // skip both } } break 2 will skip both while loops. Doc: http://php.net/manual/en/control-structures.break.php This …

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How to break from nested loops in Ruby?

Catch and throw might be what you are looking for: bank.branches do |branch| catch :missingyear do #:missingyear acts as a label branch.employees.each do |employee| (2000..2011).each do |year| throw :missingyear unless something #break out of two loops end end end #You end up here if :missingyear is thrown end