Functional constructs often express your intent more clearly than for-loops in cases where you operate on some data set and want to transform, filter or aggregate the elements. Loops are very appropriate when you want to repeatedly execute some action. For example int x = array.Sum(); much more clearly expresses your intent than int x … Read more
No you don’t. >>> ‘{0:07b}’.format(12) ‘0001100’
For-loops: For-loop in C: for(int x = 0; x<=3; x++) { //Do something! } The same loop in 8086 assembler: xor cx,cx ; cx-register is the counter, set to 0 loop1 nop ; Whatever you wanna do goes here, should not change cx inc cx ; Increment cmp cx,3 ; Compare cx to the limit … Read more
You could do this: for idx, item in enumerate(list): if ‘foo’ in item: item = replace_all(…) list[idx] = item
They are equivalent, even if you turn the optimizer off. Example: #include <stdio.h> extern void f(void) { while(1) { putchar(‘ ‘); } } extern void g(void) { for(;;){ putchar(‘ ‘); } } extern void h(void) { z: putchar(‘ ‘); goto z; } Compile with gcc -O0 gives equivalent assembly for all 3 functions: f: ; … Read more
In general, the fewer times you hit the database, the better. There are a number of reasons for this, including: The database will be able to optimize better if it can try to fetch everything all at once You remove all of the overhead of communicating with the database multiple times, which can be quite … Read more
Based on the other answers, I think the cleanest solutions are #Handles None return from get_list for item in get_list() or []: pass #do something or the comprehension equiv result = [item*item for item in get_list() or []]
What you are pointing to is Generator in Python. Take a look at: – http://wiki.python.org/moin/Generators http://www.python.org/dev/peps/pep-0255/ http://docs.python.org/whatsnew/2.5.html#pep-342-new-generator-features See the documentation: – Generator Expression which contains exactly the same example you have posted From the documentation: – Generators are a simple and powerful tool for creating iterators. They are written like regular functions but use the … Read more
Based on Tim’s second edit and this page you could do this: @echo off if “%1″==”loop” ( for /l %%f in (1,1,1000000) do ( echo %%f if exist %%f exit ) goto :eof ) cmd /v:on /q /d /c “%0 loop” echo done This page suggests a way to use a goto inside a loop, … Read more