Thread: MinGw shell vs. Microsoft command

While trying the following exercise, I found out that it runs differently depending on if I use MinGw shell or the dos command. Here is the code:

Code:

      1 #include <stdio.h>
      2 #include <conio.h>
      3 int main()
      4 {
      5 char sent[100];
      6 xputs ("Enter a sentence ...");
      7 xgets (sent);
      8 printf ("\n\n");
      9 xputs (sent);
     10 printf ("\n\n\n\n\nPress any key to exit...");
     11 getch();
     12 }
     13 xputs (char *s)
     14 {
     15 while (*s)  // I have not seen this before; I need to find out more about it
     16 {
     17 putch (*s);
     18 s++;
     19 }
     20 }
     21 xgets ( char *s)
     22 {
     23 int i;
     24 char ch;
     25
     26 for (i=0; i<=98; i++)
     27 {
     28 ch = getche ();
     29 //if (ch == 13)
     30 if (ch == '\r')
     31 {

From MinGw shell, backspace does not work very well. It actually goes back two spaces it seems. Line 30 does not seem to work when I execute from MinGw shell, and I have to use something like line 29 instead. Does this have anything to do with MinGw being based on posix?

Update: I found out why pressing backspace would cause the curser go back two spaces. I commented out the printf ("\b"); sentence and now backspace works the way it is supposed to.

My other question is about the while loop. What does line 15 do? Is that an infinite loop? Why not just do "while (1)"? I mean the author is using the break statement to leave the loop. Why use *s in the parenthesis?

Originally Posted by zolfaghar

My other question is about the while loop. What does line 15 do? Is that an infinite loop? Why not just do "while (1)"? I mean the author is using the break statement to leave the loop. Why use *s in the parenthesis?

For that, you need to understand how integer values are converted into boolean logic in C++( they're carried from C that way ):

Code:

if (c)
if (!c)

is equivalent to:

Code:

if (c != 0)
if (c == 0)

Originally Posted by Epy

conio.h is old, non-standard, and came from the MS-DOS era.

If you haven't yet found a library that gives you key presses without the need to press enter each time, you could use ncurses on Linux/Unix, or pdcurses on Windows. The API is different, but there's tons of functionality there, that you might find useful, and those two libraries are (mostly) source compatible, so code written for Windows will compile on Linux, and vice versa, as long as it doesn't use anything OS specific.