This program continually displays a scrolling message in the middle of your terminal window.
The code uses a for loop to repeatedly extract and display two portions of the message, using the substr function.
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To try out the program, select and copy the C++ source-code at the bottom of this post.
Paste into a text editor, such as Nano or Geany.
Then save the new file, ending in .cpp
I used ticker.cpp
To compile from the command-line:
g++ -o ticker ticker.cpp
To run from the command-line:
./ticker
Here's the code:
#include <iostream> // To use the screen output - cout "channel out"
#include <unistd.h> // To slow things down by parts of a second - usleep function
#include <sstream> // To convert numbers to character strings when telling the screen where to put the cursor
using namespace std; // Want to use short abbreviations... cout rather than std::cout
// -------------------------------
// These constants are special "escape characters" that tell your terminal to change colour or switch bold on/off
const string GREEN = "\e[32m";
const string BOLD = "\e[1m";
// -------------------------------
void positionCursor( int screenRow, int screenColumn )
{
// This function sends the cursor to a particular row and column in your terminal window
// ready to display something at that position.
string columnString, rowString;
// Convert the column number to a character string - uses a new stringstream each time, don't need to reset it after use...
stringstream columnConverter;
columnConverter << screenColumn;
columnConverter >> columnString;
// Convert the row number to a character string
stringstream rowConverter;
rowConverter << screenRow;
rowConverter >> rowString;
// Put the strings together to make an "escape sequence" that tells screen where to position the cursor
cout << "\e[" + rowString + ";" + columnString + "H";
}
// -------------------------------
// Program begins execution here...
int main()
{
string message = "GREET1NG$ EaRTHL1ng$! ++ ++ ++ WeLC0Me 2 GCC oN tHE Pi ++ ++ ++ ";
// Find number of characters in message
int len = message.length();
cout << GREEN << BOLD;
// Repeat the ticker-tape forever
while ( true )
{
for ( int tick = 0; tick < len; tick++ )
{
// Center message on screen
// Assumes 80 cols x 40 rows in terminal window
positionCursor( 12, 40- len/2 );
// Display left half of ticker-tape message
cout << message.substr( tick, len-tick );
// Display right half of ticker-tape message
cout << message.substr( 0, tick );
// Tell screen to update immediately
cout << flush;
// Brief pause for quarter of a second
usleep( 250000 );
} // end of for loop
} // end of while block of statements
} // end of main function
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