Extract int from string in Java

My Java is a bit rusty, but this ought to work:

String digit = temp.charAt(n);int digitvalue = Integer.parseInt(digit);// etc.

My Java is also a bit rusty, but I think charAt returns a char. So that toString is necessary.

Incidentally, kevin, "it didn't work" is not as useful a diagnostic description as you might assume.

I figured it out. The problem was that I had to do:

sum += Math.pow(Integer.parseInt(Character.toString(temp.charAt(n))), 4);

It seems like this would be so much easier in other languages. I think C++ would just be
sum = pow(temp[n] - '0', 4);

Why?

Integer division and modulo come to help and will let you avoid strings. There is no need for strings in numerical operations. Composing strings in inner loops is slow. If at all, use a string builder, but that is not good either. It is wrong practice. As soon as you discover a string and char-extractions in numerical operations you know you are making it wrong. String is evil. Strings are evil. They are the tip of the iceberg why nowadays applications waste so much memory and still run as slow as 20 years ago. Use algorithms, not strings. Algorithms are not old-school. They are what makes up a programmer. Strings are the adhesive tape that might make your application work, but they are not the solution. In corner cases and contrarius situations of high lateral acceleration where you want not to display 100 rows but 500, they make your application fail utterly. Because you were to lazy to build up a basic programmer's mindset. They are what seperates your slow-like-ass-application from top-notch software like VMWare, VirtualBox or the linux kernel. The linux kernel is not proper C, but it is properly programmatic and does not use strings in its process scheduler and memory allocator. Integer division and modulo. Avoid strings and learn at least a handful of simple algorithms. Please.

Quote:

Original post by kevin_06s I figured it out. The problem was that I had to do: sum += Math.pow(Integer.parseInt(Character.toString(temp.charAt(n))), 4); It seems like this would be so much easier in other languages. I think C++ would just be sum = pow(temp[n] - '0', 4);

Java sucks, but maybe not as much as you may think. :) You can do basically the same thing in Java too, as:

import static java.lang.Math.*;// ...sum += pow(temp.charAt(n) - '0', 4);

And the loop could be made more readable (though not necessarily more efficient) with:

import static java.lang.Math.*;// ...for (char c : temp.toCharArray()) {    sum += pow(c - '0', 4);}

Phresnel does have a point, though.

Tbh, I am even slightly surprised that the mods did not see this string abuse (sorry, mods).

If you have an integer, then the most basic way to get all digits is as simple as




--> no memory waste
--> less heat waste
--> way, way, way better performance
--> no memory waste
--> works for all bases
--> no memory waste and way, way, way better performance and less heat waste
--> additional plus for C++: base can be made a compile time constant so that not even a modulus is harmed