Thread: String question, and hello from a newcomer

hi there everyone

i've been a php and vb amateur-programmer for a while, and i've started recently learning C/C++, for my growing interest in game development.

i'm making a simple chat server, that can be accessible via telnet. i tried for about 2 hours, to find an easy way, to get the first n characters in char variable "buffer3" from the char variabile "buffer4". i was only able to do it this way:

Code:

if (SDLNet_TCP_Recv(clnt[j], buffer4, 512)) {
        buffer3[0]=buffer4[0];
        buffer3[1]=buffer4[1];
        buffer3[2]=buffer4[2];
        buffer3[3]=buffer4[3];
        buffer3[4]=buffer4[4];
        buffer3[5]=buffer4[5];

      MessageBox(NULL, buffer3, "Message", MB_ICONWARNING);       

        }

it's supposed to get data from a sdl socket, and (for the moment) just display it. isn't there an easier way to do this? like somthing buffer3=substr(buffer4,0,5) ?

i'm on a windows box, working under dev-c++.

thanks,
izuael.

edit: um, yeah. this is a very n00bish question. i've googled for some help, but they referenced on a header called string.h, and most of the functions gave an error compiling, that's why i am asking

Strncpy() does exactly what you want.
It does something like this:

Code:

char *mystrncpy(char* buffer,char* buffer2,int amount){
	int i;
	for(i=0;i<amount&&buffer[i]!='\0';i++){
		buffer2[i]=buffer[i];
	}
	buffer2[i]='\0';
	return buffer2;
}

http://www.cppreference.com/cppstring/index.html
http://www.cprogramming.com/tutorial/string.html

also, is there a way to concatenate or copy strings the "usual" way (like other languages work, say vb or php) ? with = and + ?

Yes, by using std::string objects.

The "usual" ways are actually very complicated systems, although they seem to be "easy" and "logical".

Actually, I suggest that you take a look at the C++ Book Recommendations thread. Since you already have programming experience, Accelerated C++: Practical Programming by Example is a good book for you to start learning C++.

>isn't there an easier way to do this? like somthing buffer3=substr(buffer4,0,5) ?
As Laserlight suggested, if you change buffer3 and buffer4 to be a std::string, then you can simply do:

Code:

buffer3 = buffer4.substr(0,5);

And you can copy a char array to a std::string by simply doing:

Code:

char array[100];
std::string buf = array;

Google is your friend. It's organic, healthy, safe and free of all harmful side effects. Try it today!

On a more serious note, you should try to appreciate the low-level-ness of C++, as opposed to the PHP (scripted) and vB (managed). Strings are actually nothing more than arrays of characters in RAM, referenced by a memory pointer. Code is fast, but the process of writing the code can be slow and hard, unless you are well grounded in the basics, know all the pitfalls (read the CProg FAQ to have an idea of what to expect) and have a fundemental understanding of how your machine works inside.

Not necessarily appreciate, but at least understand