It’s a CPython-specific optimization for the case when the str being appended to happens to have no other living references. The interpreter “cheats” in this case, allowing it to modify the existing string by reallocating (which can be in place, depending on heap layout) and appending the data directly, and often reducing the work significantly … Read more
I always go for the second method (using the GString template), though when there are more than a couple of parameters like you have, I tend to wrap them in ${X} as I find it makes it more readable. Running some benchmarks (using Nagai Masato‘s excellent GBench module) on these methods also shows templating is … Read more
In CPython, the standard implementation of Python, there’s an implementation detail that makes this usually O(n), implemented in the code the bytecode evaluation loop calls for + or += with two string operands. If Python detects that the left argument has no other references, it calls realloc to attempt to avoid a copy by resizing … Read more
I understand that there is a 4000 max set for NVARCHAR(MAX) Your understanding is wrong. nvarchar(max) can store up to (and beyond sometimes) 2GB of data (1 billion double byte characters). From nchar and nvarchar in Books online the grammar is nvarchar [ ( n | max ) ] The | character means these are … Read more
The “old” way output a bunch of StringBuilder-oriented operations. Consider this program: public class Example { public static void main(String[] args) { String result = args[0] + “-” + args[1] + “-” + args[2]; System.out.println(result); } } If we compile that with JDK 8 or earlier and then use javap -c Example to see the … Read more
Browser string optimizations have changed the string concatenation picture. Firefox was the first browser to optimize string concatenation. Beginning with version 1.0, the array technique is actually slower than using the plus operator in all cases. Other browsers have also optimized string concatenation, so Safari, Opera, Chrome, and Internet Explorer 8 also show better performance … Read more
There is nothing wrong in concatenating two strings with +. Indeed it’s easier to read than ”.join([a, b]). You are right though that concatenating more than 2 strings with + is an O(n^2) operation (compared to O(n) for join) and thus becomes inefficient. However this has not to do with using a loop. Even a … Read more
In your example one and two are char pointers, pointing to char constants. You cannot change the char constants pointed to by these pointers. So anything like: strcat(one,two); // append string two to string one. will not work. Instead you should have a separate variable(char array) to hold the result. Something like this: char result[100]; … Read more
In classic sh, you have to do something like: s=test1 s=”${s}test2″ (there are lots of variations on that theme, like s=”$s””test2″) In bash, you can use +=: s=test1 s+=test2
Modern string formatting: “{} and {}”.format(“string”, 1)