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std::cin question

Started by Amnesty2 Sep 19, 2013 at 4:52 AM 2 replies 1.2k views

Original Post

Amnesty2

Sep 19, 2013 at 4:52 AM

I'll give an example because i don't really know how to word it.

cout << "Input a filename :";

cin >> file;

I would like to print

Input a filename :autosave.txt_
autosave.txt can be backspaced on and edited.

I'd like to put some stuff in cins buffer before i ask and have it displayed and be editable.

i can only think of platform specific ways of achieving something similar.

Simulating key presses or rolling your input function that pops data off on backspace, pushes chars in, and sets the cursor position accordingly.

I know, iostreams let you hack around at a pretty low level with them so i assume this possible some how. Maybe?

alvaro

Sep 19, 2013 at 5:48 AM

No, there is no platform-independent way of capturing individual keystrokes in C++.

Bacterius

Sep 19, 2013 at 9:51 AM

As Alvaro says, there is no standard way of doing this. But ncurses (and its Windows port PDCurses) abstracts a lot of terminal-specific functionality under a cross-platform API which should work on a wide enough range of systems. Perhaps you could take a look and see if it meets your needs.

Tispe

Sep 19, 2013 at 11:15 AM

You can edit the last line by using '\r' in the printf() function.

like this :


const int NumDots = 65;
char s[100];
int xpos = 0;

sprintf_s(s, "X.......................................................................");

while(true){  

if(xpos>NumDots){
s[xpos] = '.'; 
xpos = 0;
s[xpos] = 'X';
 
} else {
xpos++;
s[xpos] = 'X';
s[xpos-1] = '.';
}
 Sleep(50);
                 
printf("%s\r", s);		//updates last line
}

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