Get Key Press Without Pressing Enter in Console

raw_input without pressing enter

Under Windows, you need the msvcrt module, specifically, it seems from the way you describe your problem, the function msvcrt.getch:

Read a keypress and return the
resulting character. Nothing is echoed
to the console. This call will block
if a keypress is not already
available, but will not wait for Enter
to be pressed.

(etc -- see the docs I just pointed to). For Unix, see e.g. this recipe for a simple way to build a similar getch function (see also several alternatives &c in the comment thread of that recipe).

Capture characters from standard input without waiting for enter to be pressed

That's not possible in a portable manner in pure C++, because it depends too much on the terminal used that may be connected with stdin (they are usually line buffered). You can, however use a library for that:

conio available with Windows compilers. Use the _getch() function to give you a character without waiting for the Enter key. I'm not a frequent Windows developer, but I've seen my classmates just include <conio.h> and use it. See conio.h at Wikipedia. It lists getch(), which is declared deprecated in Visual C++.
curses available for Linux. Compatible curses implementations are available for Windows too. It has also a getch() function. (try man getch to view its manpage). See Curses at Wikipedia.

I would recommend you to use curses if you aim for cross platform compatibility. That said, I'm sure there are functions that you can use to switch off line buffering (I believe that's called "raw mode", as opposed to "cooked mode" - look into man stty). Curses would handle that for you in a portable manner, if I'm not mistaken.

how to get user input without pressing enter in python?

Here is a simple example using keyboard:

import keyboard

while True:
    event = keyboard.read_event()
    if event.event_type == keyboard.KEY_DOWN:
        key = event.name
        print(f'Pressed: {key}')
        if key == 'q':
            break

Is there a way to get user input without pressing the enter key?

This works for me (I am on linux):

#include <stdio.h>
#include <unistd.h>
#include <termios.h>

int main()
{
    struct termios old_tio, new_tio;
    unsigned char c;

    /* get the terminal settings for stdin */
    tcgetattr(STDIN_FILENO,&old_tio);

    /* we want to keep the old setting to restore them a the end */
    new_tio=old_tio;

    /* disable canonical mode (buffered i/o) and local echo */
    new_tio.c_lflag &=(~ICANON & ~ECHO);

    /* set the new settings immediately */
    tcsetattr(STDIN_FILENO,TCSANOW,&new_tio);

    do {
         c=getchar();
         printf("%d ",c);
    } while(c!='q');

    /* restore the former settings */
    tcsetattr(STDIN_FILENO,TCSANOW,&old_tio);

    return 0;
}

It makes the console unbuffered.

reference: http://shtrom.ssji.net/skb/getc.html

c# console: How to ReadLine without the need of pressing [Enter]

Save the result from ReadKey and then just do a ReadLine:

   public static void Main(string[] args)
    {
        var KP = Console.ReadKey();
        if (KP.Key == ConsoleKey.F2)
        {
            return;               
        }

        string UserName = KP.KeyChar + Console.ReadLine();

        Console.WriteLine(UserName);
        Console.ReadLine();
    }