il problema è che <conio.h> non appartiene alla libreria dello standard C. (quindi potresti non trovarlo nella release di C che stai utilizzando)

Potresti sempre crearti un header ad hoc, da includere nei tuoi progetti C/C++.

codice:
//name "format_out.h"

#include <windows.h>

// gotxy() gestisce il cursore  

void gotoxy(int x, int y)
{
    COORD point;
    point.X = x; point.Y = y;
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), point);
}





// setrgb() gestisce il colore bg/fg

void setrgb(int color)
{
    switch (color)
    {
        case 0:    // White on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                        FOREGROUND_INTENSITY | FOREGROUND_RED |
                        FOREGROUND_GREEN | FOREGROUND_BLUE);
        break;
      
        case 1:    // Red on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                         FOREGROUND_INTENSITY | FOREGROUND_RED);
        break;
  
        case 2:    // Green on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                      FOREGROUND_INTENSITY | FOREGROUND_GREEN);
        break;
  
        case 3:    // Yellow on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                      FOREGROUND_INTENSITY | FOREGROUND_RED |
                      FOREGROUND_GREEN);
        break;
  
        case 4:    // Blue on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                      FOREGROUND_INTENSITY | FOREGROUND_BLUE);
        break;
  
        case 5:    // Magenta on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                     FOREGROUND_INTENSITY | FOREGROUND_RED |
                     FOREGROUND_BLUE);
        break;
  
        case 6:    // Cyan on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                    FOREGROUND_INTENSITY | FOREGROUND_GREEN |
                    FOREGROUND_BLUE);
        break;
  
        case 7:    // Black on Gray
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                  BACKGROUND_INTENSITY | BACKGROUND_INTENSITY);
        break;
  
        case 8:    // Black on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                  BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                  BACKGROUND_RED | BACKGROUND_GREEN |
                  BACKGROUND_BLUE);
        break;
  
        case 9:    // Red on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                  BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                  BACKGROUND_RED | BACKGROUND_GREEN |
                  BACKGROUND_BLUE | FOREGROUND_RED);
        break;
  
        case 10:    // Green on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                 BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                 BACKGROUND_RED | BACKGROUND_GREEN |
                 BACKGROUND_BLUE | FOREGROUND_GREEN);
        break;
  
        case 11:    // Yellow on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                 BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                 BACKGROUND_RED | BACKGROUND_GREEN |
                 BACKGROUND_BLUE | FOREGROUND_RED |
                 FOREGROUND_GREEN);
        break;
  
        case 12:    // Blue on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                 BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                 BACKGROUND_RED | BACKGROUND_GREEN |
                 BACKGROUND_BLUE | FOREGROUND_BLUE);
        break;
  
        case 13:    // Magenta on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                 BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                 BACKGROUND_RED | BACKGROUND_GREEN |
                 BACKGROUND_BLUE | FOREGROUND_RED |
                 FOREGROUND_BLUE);
        break;
  
        case 14:    // Cyan on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                 BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                 BACKGROUND_RED | BACKGROUND_GREEN |
                 BACKGROUND_BLUE | FOREGROUND_GREEN |
                 FOREGROUND_BLUE);
        break;
  
        case 15:    // White on White
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                BACKGROUND_INTENSITY | FOREGROUND_INTENSITY |
                BACKGROUND_RED | BACKGROUND_GREEN |
                BACKGROUND_BLUE | FOREGROUND_RED |
                FOREGROUND_GREEN | FOREGROUND_BLUE);
        break;
  
        default :    // White on Black
            SetConsoleTextAttribute(GetStdHandle(STD_OUTPUT_HANDLE),
                FOREGROUND_INTENSITY | FOREGROUND_RED |
                FOREGROUND_GREEN | FOREGROUND_BLUE);
        break;
    }      
}










// clrscr() pulisce lo schermo

void clrscr()
{
    COORD coordScreen = { 0, 0 }; 
    DWORD cCharsWritten; 
    CONSOLE_SCREEN_BUFFER_INFO csbi; 
    DWORD dwConSize; 
    HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE); 
    GetConsoleScreenBufferInfo(hConsole, &csbi); 
    dwConSize = csbi.dwSize.X * csbi.dwSize.Y; 
    FillConsoleOutputCharacter(hConsole, TEXT(' '), dwConSize, coordScreen, &cCharsWritten); 
    GetConsoleScreenBufferInfo(hConsole, &csbi); 
    FillConsoleOutputAttribute(hConsole, csbi.wAttributes, dwConSize, coordScreen, &cCharsWritten); 
    SetConsoleCursorPosition(hConsole, coordScreen); 
}