而用C读取字符打印 [英] Printing while reading characters in C

问题描述

我想写code的一个简单的小片段向方向键preSS回应。
我知道了重新由^ [[A psented $ P $，我有以下的code，检查该序列：

I'm trying to write a simple little snippet of code to respond to an arrow key press. I know that up is represented by ^[[A, and I have the following code that checks for that sequence:

     while( 1 )
     {
         input_char = fgetc( stdin );

         if( input_char == EOF || input_char == '\n' )
         {
             break;
         }

         /* Escape sequence */
         if( input_char == 27 )
         {
             input_char = getc( stdin );

             if( input_char == '[' )
             {
                 switch( getc( stdin ) )
                 {
                     case 'A':
                     printf("Move up\n");
                     break;
                 }
             }
         }
     }

每当我打向上，转义序列（^ [[A）显示在屏幕上，但上移没有出现，直到我按下回车键。

Whenever I hit "up", the escape sequence (^[[A) shows up on the screen, but "Move up" doesn't appear until I hit enter.

的最终目标是，以取代一些其他数据的当前行的文本，所以我试图做

The end goal is to replace the text on the current line with some other data, and so I tried to do

printf("\r%s", "New Text");

代替上移，但它仍然没有露面，直到进入后是pressed。

in place of "Move up", but it still doesn't show up until after enter is pressed.

时有什么错，我读字符的方式？

Is there something wrong with the way I'm reading in characters?

谢谢！

的修改的快速笔记，这​​对* nix系统。

EDIT Quick note, it's for *nix systems.

SOLUTION 的
感谢大家的指针。我stepanbujnak的解决方案了，因为它是非常简单。有一件事我注意到的是，有很多修改字符串（退格等）键的行为是不同的比你期望的那样。它将通过就行了（包括printf'd东西）任何东西退格，我不得不考虑到这一点。之后，它不是太坏得到休息加入行列：）

SOLUTION Thanks for the pointers everyone. I went with stepanbujnak's solution because it was rather straightforward. The one thing I noticed is that a lot of the behavior of keys that modify the string ( backspace, etc ) is different than you would expect. It will backspace through ANYTHING on the line (including printf'd stuff), and I had to account for that. After that it wasn't too bad getting the rest to fall in line :)

推荐答案

您实际上只需要使用禁用行缓冲的的termios

You actually only need to disable line buffering using termios

下面是这样做的例子：

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

int main() {
  struct termios old_term, new_term;
  char c;

  /* Get old terminal settings for further restoration */
  tcgetattr(0, &old_term);

  /* Copy the settings to the new value */
  new_term = old_term;

  /* Disable echo of the character and line buffering */
  new_term.c_lflag &= (~ICANON & ~ECHO);
  /* Set new settings to the terminal */
  tcsetattr(0, TCSANOW, &new_term);

  while ((c = getchar()) != 'q') {
    printf("You pressed: %c\n", c);
  }

  /* Restore old settings */
  tcsetattr(0, TCSANOW, &old_term);

  return 0;
}

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