What ways to pause the program for a time (sec) do you know?

#include <unistd.h>
...
...
sleep(2);//2 секунды
usleep(1000000);//1 секунда (1.000.000 микросекунд)

Note that when checking these functions, printf must either end the print with "\n", or set flush: fflush(stdout); immediately after the print, for example:

printf("1");
fflush(stdout);
sleep(1);
printf(" - 2");

The same applies to cout. The analog of fflush(stdout) is cout.flush();

PS There is no such thing in Windows, but there is a replacement:

#include <windows.h>
Sleep(1000);//1 секунда - 1.000 миллисекунд

The canonical C++ method is to use std::this_thread::sleep_for

#include <chrono>
#include <thread>

int main() {
  std::this_thread::sleep_for(std::chrono::seconds(2));
}

Starting with C++14, you can write

using namespace std::literals;
std::this_thread::sleep_for(2s);

1. sleep()and delay () - from the standard c library (I don't remember which one),
2. Sleep () - WinAPI from windows. h
3. Use for, while loops for the delay. I also heard that there is a wait () function;

Sleep () and delay() here's a good article

#include <iostream>    
int main(){

    using namespace std;
        for (float ex = 0; ex <=4; ex=ex+0.10) {
           system("cls");
           cout<<"Exit through 4 second"<<endl;
           cout<<" ";
                     }
          exit(0);

    return 0;

}

As an option)