c - 在 C 程序中移动光标

Question

我想在 C 程序中前后移动光标。我正在循环阅读整行，但我希望如果按下光标键，屏幕上的光标会改变位置，而不会阻塞循环。我尝试了 getwch() 但它会阻止调用者直到按下输入。我正在寻找的是类似于 bash 提示符的行为。我正在阅读与此类似的代码:

while (TRUE) {
   printf("%s", PROMPT);
   fgets(input, 1024, stdin);
   do_something(input);
}

我正在尝试让上面的函数像 readline.h 库中的 readline(PROMPT) 一样工作

Answer 1

使用 termios 和控制台代码(兼容 VT100 - 不可移植):

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

#define cursorforward(x) printf("\033[%dC", (x))
#define cursorbackward(x) printf("\033[%dD", (x))

#define KEY_ESCAPE  0x001b
#define KEY_ENTER   0x000a
#define KEY_UP      0x0105
#define KEY_DOWN    0x0106
#define KEY_LEFT    0x0107
#define KEY_RIGHT   0x0108

static struct termios term, oterm;

static int getch(void);
static int kbhit(void);
static int kbesc(void);
static int kbget(void);

static int getch(void)
{
    int c = 0;

    tcgetattr(0, &oterm);
    memcpy(&term, &oterm, sizeof(term));
    term.c_lflag &= ~(ICANON | ECHO);
    term.c_cc[VMIN] = 1;
    term.c_cc[VTIME] = 0;
    tcsetattr(0, TCSANOW, &term);
    c = getchar();
    tcsetattr(0, TCSANOW, &oterm);
    return c;
}

static int kbhit(void)
{
    int c = 0;

    tcgetattr(0, &oterm);
    memcpy(&term, &oterm, sizeof(term));
    term.c_lflag &= ~(ICANON | ECHO);
    term.c_cc[VMIN] = 0;
    term.c_cc[VTIME] = 1;
    tcsetattr(0, TCSANOW, &term);
    c = getchar();
    tcsetattr(0, TCSANOW, &oterm);
    if (c != -1) ungetc(c, stdin);
    return ((c != -1) ? 1 : 0);
}

static int kbesc(void)
{
    int c;

    if (!kbhit()) return KEY_ESCAPE;
    c = getch();
    if (c == '[') {
        switch (getch()) {
            case 'A':
                c = KEY_UP;
                break;
            case 'B':
                c = KEY_DOWN;
                break;
            case 'C':
                c = KEY_LEFT;
                break;
            case 'D':
                c = KEY_RIGHT;
                break;
            default:
                c = 0;
                break;
        }
    } else {
        c = 0;
    }
    if (c == 0) while (kbhit()) getch();
    return c;
}

static int kbget(void)
{
    int c;

    c = getch();
    return (c == KEY_ESCAPE) ? kbesc() : c;
}

int main(void)
{
    int c;

    while (1) {
        c = kbget();
        if (c == KEY_ENTER || c == KEY_ESCAPE || c == KEY_UP || c == KEY_DOWN) {
            break;
        } else
        if (c == KEY_RIGHT) {
            cursorbackward(1);
        } else
        if (c == KEY_LEFT) {
            cursorforward(1);
        } else {
            putchar(c);
        }
    }
    printf("\n");
    return 0;
}