#include <conio.h>

if (kbhit() != 0) {
    cout << getch() << endl;
}

它使用kbhit()来检查键盘是否被按下，并使用getch()来获取被按下的字符。

这在纯c++中以可移植的方式是不可能的，因为它太依赖于可能与stdin连接的终端(它们通常是行缓冲的)。不过，你可以使用一个库来实现:

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.

如果你的目标是跨平台兼容性，我建议你使用curses。也就是说，我相信有一些函数可以用来关闭行缓冲(我相信这被称为“原始模式”，而不是“熟模式”-看看man stty)。如果我没记错的话，诅咒可以方便地帮你解决这个问题。

在WINDOWS上我这样做:

#include <Windows.h>
int main()
{
    system("PAUSE>NUL");
    if (GetKeyState(0x41/*(the 'A' key, choosen e.g.)*/) & (0xff80/*That stands for "Default state / Key Down"*/)) {
        //whatever I want to do after 'A' is pressed
    }
}

这里可以找到一个键的列表，每个键都有自己的十六进制值: https://learn.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes

管道演示:如何从C语言的系统调用管道读取键盘按键

理想情况下，它也不会将输入字符回显到屏幕上。我只是想在不影响控制台屏幕的情况下捕捉击键。

要在Linux上做到这一点，您可以使用以下bash命令:

read -sn1 c && printf "You Pressed: %s\n" "$c"

请看我在这里的回答关于这个的详细信息:shell脚本响应按键。

因此，要在Linux上的C或c++中做到这一点，您只需要通过使用popen()和fgets()的管道通过系统调用调用上面的bash命令，这样您就可以从bash命令读取输出。

下面是一个完整的例子，在Linux上运行良好的C和c++:

read_system_call_via_pipe__keypress.c:

#include <stdbool.h> // For `true` (`1`) and `false` (`0`) macros in C
#include <stdint.h>  // For `uint8_t`, `int8_t`, etc.
#include <stdio.h>   // For `printf()`
#include <stdlib.h>

#define BUFSIZE 32

// Read a keyboard key press and return the character pressed, or a negative
// number in the event of an error.
// NB: for help reading output from system calls, see here:
//  1. https://stackoverflow.com/a/28971647/4561887
//  2. https://stackoverflow.com/a/18297075/4561887
char getKeypress()
{
    // This bash cmd is from my answer here:
    // https://stackoverflow.com/a/70979348/4561887
    const char* cmd = "bash -c 'read -s -n1 c && printf \"%s\" \"$c\"'";
    FILE *fp = popen(cmd, "r");
    if (fp == NULL)
    {
        printf("\nError opening pipe!\n");
        return -1;
    }

    char buf[BUFSIZE] = {0};
    char* retval1 = fgets(buf, BUFSIZE, fp);
    if (retval1 == NULL)
    {
        printf("\nFailed to read cmd response.\n");
        return -2;
    }

    // See meaning of this return value here:
    // https://stackoverflow.com/questions/43116/how-can-i-run-an-external-program-from-c-and-parse-its-output/28971647#comment60311936_28971647
    int retval2 = pclose(fp);
    if (retval2 == -1)
    {
        printf("\nError obtaining the cmd's exit status code.\n");
        return -3;
    }
    else if (retval2 != 0)
    {
        printf("\nCommand exited with exit status code %i.\n", retval2);
        return -4;
    }

    char keyPressed = buf[0];
    return keyPressed;
}

// int main(int argc, char *argv[])  // alternative prototype
int main()
{
    printf("Press any key to continue: ");
    fflush(stdout);
    char keyPressed = getKeypress();
    if (keyPressed > 0)
    {
        printf("\nKey pressed = %c\n", keyPressed);
    }

    return 0;
}

C和c++编译和运行命令是下面输出的一部分。下面是一些演示:

在C:

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=gnu17 read_keypress_system_call.c -o bin/a && bin/a
Press any key to continue:
Key pressed = P

或，在c++中:

eRCaGuy_hello_world/c$ g++ -Wall -Wextra -Werror -O3 -std=c++17 read_keypress_system_call.c -o bin/a && bin/a
Press any key to continue:
Key pressed = u

参见:

要更进一步，请参阅我在这里的另一个回答，我一次检测并解析3个字符，以便检测方向键的向上、向下、向左或向右:在C语言中读取键按下。方向键，Enter键

引用:

How I learned to read from a pipe to get system call output: How can I run an external program from C and parse its output? Is there a way to obtain the output of a linux command(like ifconfig) on a .txt file using a C program? [duplicate] How to compile and use popen() in C: use -std=gnu17 instead of -std=c17: popen implicitly declared even though #include <stdio.h> is added [my answer] How to read without blocking, via bash: shell script respond to keypress [my answer] How do I read in the Enter key as an input in C?

关于这个话题的3个问题

从标准输入中捕获字符，而不需要等待按enter键 C非阻塞键盘输入 如何避免按Enter与getchar()只为读取单个字符?

我使用kbhit()来查看是否存在一个字符，然后使用getchar()来读取数据。 在windows上，您可以使用“conio.h”。在linux上，您必须实现自己的kbhit()。

参见下面的代码:

// kbhit
#include <stdio.h>
#include <sys/ioctl.h> // For FIONREAD
#include <termios.h>
#include <stdbool.h>

int kbhit(void) {
    static bool initflag = false;
    static const int STDIN = 0;

    if (!initflag) {
        // Use termios to turn off line buffering
        struct termios term;
        tcgetattr(STDIN, &term);
        term.c_lflag &= ~ICANON;
        tcsetattr(STDIN, TCSANOW, &term);
        setbuf(stdin, NULL);
        initflag = true;
    }

    int nbbytes;
    ioctl(STDIN, FIONREAD, &nbbytes);  // 0 is STDIN
    return nbbytes;
}

// main
#include <unistd.h>

int main(int argc, char** argv) {
    char c;
    //setbuf(stdout, NULL); // Optional: No buffering.
    //setbuf(stdin, NULL);  // Optional: No buffering.
    printf("Press key");
    while (!kbhit()) {
        printf(".");
        fflush(stdout);
        sleep(1);
    }
    c = getchar();
    printf("\nChar received:%c\n", c);
    printf("Done.\n");

    return 0;
}

最接近可移植的方法是使用ncurses库将终端置于“cbreak模式”。API是巨大的;你最想要的是

Initscr和endwin 黄昏时分和黄昏时分 getch

好运！