Thread: How can I make a scroll bar in c++?

How can I make a scrolling text in c++?

If someone know some code that can read an external file and make it scroll on the program window, lease help me!!!

>How can I make a scroll bar in c++?
With a windowing API.

>If someone know some code that can read an external file and make it scroll on the program window, lease help me!!!
Is this on a textual command line or a GUI based program?

A short question deserves a short answer.
Look here.

Since you did not specify what API, I assume you're using the Windows API.

read an external file and make it scroll on the program window

For the reading I would use <iostream>. I don't know what kind of window "program window" is, but I would just use SetWindowText() on a multiline edit control.

I was bored, so here's a way to scroll with a text interface:

Code:

#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <stdlib.h>
#include <conio.h>

using namespace std;

vector<string> map_file ( ifstream& in );

int main()
{
  ifstream in ( "input.txt" );

  if ( !in.is_open() )
    return EXIT_FAILURE;
  vector<string> file = map_file ( in );
  vector<string>::size_type scroll = 0;

  cout<<"How to scroll: Up = j, Down = k, Quit = q"<<endl;
  for ( ; ; ) {
    cout<< file[scroll] <<endl;
    switch ( getch() ) {
    case 'j':
      if ( scroll > 0 )
        scroll--;
      break;
    case 'k':
      if ( scroll < file.size() - 1 )
        scroll++;
      break;
    case 'q':
      return EXIT_SUCCESS;
    }
  }
}

vector<string> map_file ( ifstream& in )
{
  vector<string> file;
  string line;

  while ( getline ( in, line ) )
    file.push_back ( line );

  return file;
}

"But Prelude, it only scrolls one line at a time!" Duh, of course it does, but adding the functionality for more than one line at a time is simple enough to be left as an exercise.

two questions about this.....
a) what does the last function do?
it returns a vector of strings and takes a reference to an ifstream object is all i know.

b) : vector<string>::size_type scroll = 0;
what is that? is size_type an enum or what?

>a) what does the last function do?
It reads the contents of a file, line by line, into a vector of strings. It's a convenience function so that you don't have to do it in main.

>what is that? is size_type an enum or what?
size_type is a type (usually a typedef) defined by std::vector to represent a value that holds a valid index. It is equivalent to size_t in function, except restricted to vectors.

so size_type is used to prevent overrun?

vector<string>::size_type scroll = 0;
and this is (im guessing here.....) a static member variable?