The difference is that in x < y < z y is only evaluated once. This does not make a large difference if y is a variable, but it does when it is a function call, which takes some time to compute. from time import sleep def y(): sleep(.2) return 1.3 %timeit 1.2 < y() … Read more
Instead of guessing, I decided to actually look at the generated code with a small piece of C++ code and a somewhat old Linux install. class MyException { public: MyException() { } ~MyException() { } }; void my_throwing_function(bool throwit) { if (throwit) throw MyException(); } void another_function(); void log(unsigned count); void my_catching_function() { log(0); try … Read more
What Assaf said is correct. There is a built in function in PHP to do exactly that. substr_compare($str, $test, strlen($str)-strlen($test), strlen($test)) === 0; If $test is longer than $str PHP will give a warning, so you need to check for that first. function endswith($string, $test) { $strlen = strlen($string); $testlen = strlen($test); if ($testlen > … Read more
The first is more idiomatic. In particular, it indicates (in a 0-based sense) the number of iterations. When using something 1-based (e.g. JDBC, IIRC) I might be tempted to use <=. So: for (int i=0; i < count; i++) // For 0-based APIs for (int i=1; i <= count; i++) // For 1-based APIs I … Read more
I personally feel like $array[] is cleaner to look at, and honestly splitting hairs over milliseconds is pretty irrelevant unless you plan on appending hundreds of thousands of strings to your array. I ran this code: $t = microtime(true); $array = array(); for($i = 0; $i < 10000; $i++) { $array[] = $i; } print … Read more
In strict mode, the this context is not forced to be an object. If you call a function on a non-object, this will just be that non-object. In contrast, in non-strict mode, the this context is always first wrapped in an object if it’s not already an object. For example, (42).toString() first wraps 42 in … Read more
The problem in this particular case is that you return from within the for-expression. That in turn gets translated into a throw of a NonLocalReturnException, which is caught at the enclosing method. The optimizer can eliminate the foreach but cannot yet eliminate the throw/catch. And throw/catch is expensive. But since such nested returns are rare … Read more
Summary: no speed difference; this great collaborative Ruby style guide recommends being consistent. I now use ‘string’ unless interpolation is needed (option A in the guide) and like it, but you will typically see more code with “string”. Details: Theoretically, it can make a difference when your code is parsed, but not only should you … Read more
Python: time python -c ‘for i in xrange(int(1e8)): t=12341234234.234 / 2.0’ real 0m26.676s user 0m25.154s sys 0m0.076s time python -c ‘for i in xrange(int(1e8)): t=12341234234.234 * 0.5’ real 0m17.932s user 0m16.481s sys 0m0.048s multiplication is 33% faster Lua: time lua -e ‘for i=1,1e8 do t=12341234234.234 / 2.0 end’ real 0m7.956s user 0m7.332s sys 0m0.032s time … Read more
Use System.nanoTime to get the current time. long startTime = System.nanoTime(); …..your program…. long endTime = System.nanoTime(); long totalTime = endTime – startTime; System.out.println(totalTime); The above code prints the running time of the program in nanoseconds.