C++ help

[liquid_gen]

I dont know if this is allowed but i need help with C++. I dont think it should be a problem cos i dont want help with an algorithm for a problem. its just that i quite often need to manipulate ints as strings etc and i dont really know how to so i cant solve the question despite knowing what to do as far as my algorithms concerned.
So anyone know how i can treat int as strings in C++?

[xenon]

I don't exactly understand what you mean, but you can 'print' an integer to a string using the function sprintf. It is more C then C++ and it targets a char array rather than a string class, but I know too little of C++ to be of help for it. In C:

Code: Select all

#include <stdio.h>

int main(){
   int my_int;
   char my_string[16];

   my_int=123456;
   sprintf(my_string,"%d",my_int);
   /* my string now contains "123456" */

   return 0;
}

In the second argument, the format string, you can use all formatting options that you also have with the normal printf function.

[liquid_gen]

Yes thats basically what i need though i'd prefer a C++ version and also i'd like to know how to do the reverse (i.e. strings to ints)
Thanks for your help so far mate

[daniel.is.fischer]

Again rather C than C++: string to int conversion via 'atoi', 'atoll', 'strtoull' and such, just do "man atoi" in bash (if you're on windows, I don't know if that has man pages )

[xenon]

Atoi and it's cousins are fine. You can also use sscanf which is the 'opposite' of sprintf (just like scanf is the opposite of printf):

Code: Select all

#include <stdio.h>
#include <string.h>

int main(){
   char my_string[16];
   int my_int;

   strcpy(my_string,"987654");
   sscanf(my_string,"%d",&my_int);
   /* my int now contains 987654 */

   return 0;
}

Still, this is pure C. I found this http://www.parashift.com/c++-faq-lite/m ... ssues.html for C++, which looks unnecessarily complex to me (but I always have that with C++).

[ed_r]

liquid_gen, I am in awe of your courage. It seems like C++ might be your first programming language? I mean, before having learnt C? That is astounding bravado - well done, sir!

In case it's not too late to turn you away from the dark side, I googled "C++ rant" (just on the off-chance, y' know) and found this. Scroll down to the bit that starts "C++ is philosophically and cognitively unsound ..." and draw your own conclusions!

Good luck!

[stijn263]

nvm

[daniel.is.fischer]

Scroll down to the bit that starts "C++ is philosophically and cognitively unsound ..." and draw your own conclusions!

Good luck!

But couldn't the same be said about practically all languages?
Take C, there you find declarations like char p, *q, a[10];
That is not only philosophically and cognitively unsound as it mixes quite different types, but also plain wrong because neither '*' nor '[' or ']' are valid identifier characters.

[ed_r]

From what I could make out, I figured the C++ rant was more to do with program design than syntax. Your char p, *q, a[10] example looks to me like nothing more serious than syntactic sugar. But yeah, I agree with your point: C++ is not alone in having its detractors. I'm not about to get into a fight about this.

It was only supposed to be a lighthearted remark!

[daniel.is.fischer]

Wasn't taken as anything else, I just pitied the poor C++ folks and wanted to comfort them a little

Edit: Just saw the rant was by Erik Naggum. That explains the harsh words.

P.S.: Being a Haskeller, thus having been exposed to the advantages of static (and strict) typing, my example seems a bit more than just syntactic sugar to me. Had I one quid for every time I've fallen into the trap and wrote a declaration like int[] ar; or int* a,b,c; meaning to define three pointers, I'd be rather well off. Fortunately I always compile my C code with gcc -O3 -Wall, so they're always caught at compile time.

[joshbowman205]

I agree c++ isnt perfect but i think perhaps its a useful step before moving on to C# or java.

anyone willing to dispute that its the fastest language?

[daniel.is.fischer]

As far as I know C is faster than C++ (unless you write C in C++) and if you know what to do, assembly language should be the fastest. But speed isn't everything, safety is often also important and there C/C++ are less impressive.
Choose the language(s) you're most comfortable with.