Member Avatar for neotaunter

Please help... This is driving me nuts. I have been searching for an answer to this for a few days now.

In c...

How do you stop a line feed or new line after pressing enter for an input. I want the printed information to appear on the same line as the input. Nothing I have tried prevents the cursor from moving to the next line after typing an integer then pressing enter. There has got to be a simple answer to this.

My appologies if this has been answered before, but my searches keep coming up empty.

Here is what I get:

Input Output
27
27

What I want it:

Input Output
27 27

Thanks for any assistance you can provide.

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  • Latest Post Latest Post by Ancient Dragon

Dani AI

Generated

You are running into a terminal behavior, not a C language feature. When you press Enter in canonical mode, the terminal echoes a newline and moves the cursor to the next line. ISO C has no cursor-positioning or echo control, so you must either use a terminal library (ncurses/terminfo) or manage the terminal with POSIX APIs or escape sequences. On Linux, termios controls echo and canonical mode, while libraries like ncurses give you move()/printw() to place text wherever you want. (c-faq.com, man7.org)

If you just want a light-weight fix that works on ANSI/VT-compatible terminals (most Linux terminals), read the number normally, then move the cursor back to the previous line and print your output after the digits you typed:

#include <stdio.h>

int main(void) {
    int n;
    printf("Input    Output\n");
    if (scanf("%d", &n) == 1) {
        char buf[32];
        int len = snprintf(buf, sizeof buf, "%d", n);  /* number of digits typed */
        if (len < 0) len = 0;
        printf("\033[F");                 /* go to start of previous line */
        printf("\033[%dC %d\n", len + 1, n); /* skip past input and print output */
        fflush(stdout);
    }
    return 0;
}

The \033[F (CPL: cursor to previous line) and \033[nC (CUF: cursor forward n cols) control codes are defined by ECMA-48 and are implemented by the Linux console and common terminal emulators. (man7.org)

For a more robust, portable approach on SUSE, follow /@Ancient Dragon’s suggestion and use ncurses: read input with getstr()/wgetnstr(), then move(y, x) to the same line and printw() the result, finishing with refresh(). Link with -lncurses. See the curs_move man page for details. (man7.org)

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Member Avatar for gerard4143

You may want to investigate conio.h or curese.h libraries for this behaviour.

commented: No one sane should be using those relics. -1
Member Avatar for Ancient Dragon

With a MS-Windows 32-bit (or 64-bit) compiler you will have to use the console functions in windows.h to get and set the current cursor position. Something like this:

#include <Windows.h>
#include <stdio.h>

void gotoxy(int x, int y)
{
    // set the current cursor position
    COORD coord;
    coord.X = x;
    coord.Y = y;
    SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);
}

COORD getxy()
{
    // get the current cursor position
    CONSOLE_SCREEN_BUFFER_INFO info;
    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &info);
    return info.dwCursorPosition;
}

int ndigits(int n)
{
    // calculate the number of digits in an integer
    int x = 0;
    while( n > 0)
    {
        x++;
        n /= 10;
    }
    return x;
}

int main(int argc, char* argv[])
{
    int x,y;
    COORD coord1, coord2;
    printf("Enter two numbers\n");
    coord1 = getxy();
    scanf("%d", &x);
    coord2 = getxy();
    if( coord2.Y != coord1.Y )
    {
        gotoxy(coord2.X+ndigits(x)+1, coord1.Y);
    }
    scanf("%d", &y);
    
	return 0;
}
Edited by Ancient Dragon because: n/a
Member Avatar for neotaunter

Thanks, I will go take a look at conio.h and curese.h

Thanks for the windows.h info (and sorry I should have mentioned it...), but I'm running Suse Linux and compiling with gcc. So, I need a more universal answer to this using hopefully the C Standard Library.

Member Avatar for Ancient Dragon

There is no universal answer -- only 3d party libraries such as curses.h. You can do something similar to what I posted by using terminfo functions but it would be easier to just use curses. I looked at conio.h and did not see anything useful there, at least not in the Microsoft port of that file.

Member Avatar for hinduengg

May be this could fix your problem , run it .
I tried it worked, I cant figure out any other alternate way to it in C

#include<graphics.h>
#include<conio.h>
#include<stdio.h>

int main()
{
int ip;
int gd=DETECT,gm;
initgraph(&gd,&gm," ");
cscanf("%d",&ip);
getch();
printf("Input Output \n");
printf("%d    %d",ip , ip);
getch();
return 0;
}
Member Avatar for hinduengg

One thing which is very important is that you need to
input your number on screen through keyboard blindly
without computer prompting you

In a nutshell:
Just enter your number once
and then press enter key

You will have your result!

Member Avatar for Ancient Dragon

May be this could fix your problem , run it .
I tried it worked, I cant figure out any other alternate way to it in C

#include<graphics.h>
#include<conio.h>
#include<stdio.h>

int main()
{
int ip;
int gd=DETECT,gm;
initgraph(&gd,&gm," ");
cscanf("%d",&ip);
getch();
printf("Input Output \n");
printf("%d    %d",ip , ip);
getch();
return 0;
}

Let me guess -- you are using Turbo C or Turbo C++ compiler. graphics.h is obsolete and not supported by any modern compiler, although there might be a 32-bit port of it that I am not aware of.

And the OP has already stated that he is using *nix, not MS-Windows. So that code, like the one I posted, is of no value to him.

Edited by Ancient Dragon because: n/a
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