Thread: Applications For C++

Originally Posted by Krak

I mean, you've got your silly little Celsius-to-Farenheit converter programs

tell that to NASA and watch yourself walk out of an interview witout a job

Originally Posted by Krak

but then you also have cool-ass little console programs that read data off disks

look into the <fstream> header

Originally Posted by Krak

can even perform some lower-level tasks and such.

ask some of the old-timers - a good amount of them have created operating systems, but you'll need to know a little assembly

Originally Posted by Krak

Oh, and....how are pointers to functions useful, too?

you may want to get past this before you try understanding more complex code...

>> Oh, and....how are pointers to functions useful, too?
I think he's talking about function pointers, dougdbug

Function pointers are nice if you want to avoid a bunch of branching statements, i.e.:

Code:

//Very annoying:
switch(state)
{
case INIT_STATE:
   doFunction1();
   break;
case RUN_STATE_1:
   doFunction2();
   break;
case RUN_STATE_2:
   doFunction3();
   break;
 //etc..
}

void doFunction1()
{
   //do something
   state = RUN_STATE_1;
}

You can replace this with:

Code:

void (*stateFunction)(void);  //declared somewhere, modified by various functions
stateFunction = &doFunction1;

stateFunction();

-----

void doFunction1()
{
   //do something
   stateFunction = &doFunction2;
}

In this example you'll improve efficiency too, because you'll have eliminated a branching statement. Of course I rarely do something like this, but it's something you can do. Another example is callback routines - you might want to specify, when something happens you want a certain function to be called. Well, you'd just set a function pointer to the function you want, and the function you specified would be called when that something happens. This is especially useful for applications like scripting engines:

Code:

typedef void (*funcPtr)();
map<string, funcPtr> funcMap;
funcMap["attack"] = &attack;
funcMap["jump"] = &jump;

...

string cmd;
getline(cin, cmd);
map<string, funcPtr>::iterator it = funcMap.find(cmd);
if(it != funcMap.end())
  (it->second)();

Something along those lines.

About the function pointers: It tries to get around the fact that functions are not treated as first class objects in C++. I very ocassionally use them for callback functions, but I much prefer functors (function objects) to function pointers.