Reading one character from stdin to D

Several options, depending on what you need:

If you just want a character for programming, but don't mind buffering it with a string:

• Use rawRead
  
  or byChunk
  
  to buffer its block ( stdin
  
  is an instance std.stdio.File
  
  , so all methods from this http://dlang.org/phobos/std_stdio.html available to it) and read one element from that array at the same time.

• Use a C function fgetc
  
  on import core.stdc.stdio;
  
  and use C stdin instead of a D wrapper. They are both compatible with each other, so reading from one will not mess up the buffering of the other.

• Use a function readf
  
  to capture one piece of data at a time.

All of these options will work for your program, but you will notice that the user will still have to hit the enter key until the program does anything, because the main input stream is buffered to one full line at a time. This can also be changed:

If you need one key at once, for things like interactive sessions with a user:

• See CyberShadow link in comment

• Disable line buffering when calling the operating system. This means, tcsetattr
  
  on Posix and SetConsoleMode
  
  on Windows - search the web for details on how to turn off line buffering in C, and the same code can be easily translated to D. Also see the source on my terminal.d that does this: https: //github.com/adamdruppe/arsd/blob/master/terminal.d#L1078

• Just use a library like my terminal.d which provides a framework to change the buffering mode for you and functions like getch
  
  and kbhit
  
  similar to the old one conio.h
  
  in the link. Here's a sample file: http://arsdnet.net/dcode/book/chapter_12/07/input.d which shows a simple "press any key to continue" example.

• Use a more functional C library, for example ncurses
  
  from D. http://code.dlang.org/packages/ncurses If you've ever used it from C it's pretty much the same.