You may want to re-read The Rust Programming Language, specifically the sections on: mutability mutable references vectors We can also iterate over mutable references to each element in a mutable vector in order to make changes to all the elements. The for loop in Listing 8-9 will add 50 to each element. let mut v … Read more
These are the reasons I would choose one over the other: For-loop Syntax: for( int i = 0; i < 10; i++) { //Some code here } I would use a for loop for the reason that I may KNOW the NUMBER OF ITERATIONS I need to do and I have an INCREMENTING variable which … Read more
@echo off set MYDIR=C:\FOLDER1\FOLDER2\FOLDER3\ if “%MYDIR:~-1%” == “\” set “MYDIR1=%MYDIR:~0,-1%” for %%f in (“%MYDIR1%”) do set “myfolder=%%~nxf” echo %myfolder% outputs FOLDER3
That’s not how you do it. >>> ”.join([‘first’, ‘second’, ‘other’]) ‘firstsecondother’ is what you want. If you do it in a for loop, it’s going to be inefficient as string “addition”/concatenation doesn’t scale well (but of course it’s possible): >>> mylist = [‘first’, ‘second’, ‘other’] >>> s = “” >>> for item in mylist: … … Read more
Yes, semantically it will be evaluated on every loop. In some cases, compilers may be able to remove the condition from the loop automatically – but not always. In particular: void foo(const struct rect *r) { for (int i = 0; i < r->width * r->height; i++) { quux(); } } The compiler will not … 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 []]
In theory, it is called each time, since a for loop: for(initialization; condition; increment) body; is expanded to something like { initialization; while(condition) { body; increment; } } (notice the curly braces, because initialization is already in an inner scope) In practice, if the compiler understands that a piece of your condition is invariant through … Read more
You can achieve this like following : map<string, int>::iterator it; for (it = symbolTable.begin(); it != symbolTable.end(); it++) { std::cout << it->first // string (key) << ‘:’ << it->second // string’s value << std::endl; } With C++11 ( and onwards ), for (auto const& x : symbolTable) { std::cout << x.first // string (key) << … Read more
According to the standard specification: 1 … names declared in the for-init-statement are in the same declarative-region as those declared in the condition 3 If the for-init-statement is a declaration, the scope of the name(s) declared extends to the end of the for-statement. [ยง6.5.3] and 4 Names declared in the for-init-statement, the for-range-declaration, and in … Read more
Like the error message suggests, dictionaries in Python do not provide an append operation. You can instead just assign new values to their respective keys in a dictionary. mydict = {} mydict[‘item’] = input_value If you’re wanting to append values as they’re entered you could instead use a list. mylist = [] mylist.append(input_value) Your line … Read more