getch returns 2 characters when I type one

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When I use getch, it always appends the caracter read with a null character.

When I use the following code:

#include "stdafx.h"

#include <conio.h>



int main()

{

    char c = 0;



    while (c != 'x')

    {

        c = _getch();

        printf("Char read: <%c> n", c);

    }

}

It returns the follwing on the console, when I press the keys "asdx":

Char read: <a>

Char read: < >

Char read: <s>

Char read: < >

Char read: <d>

Char read: < >

Char read: <x>

This is compiled in VS 2017 in a plain new single file project, running on a windows 10 console window. I tried removing the _UNICODE and UNICODE define.

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

How do you know it's a null character? BTW _getch() returns int.

– n.m.
Aug 10 '18 at 18:48

2

works as expected for me, have you tried printing the numerical value of c to see what it is?

– Alan Birtles
Aug 10 '18 at 18:48

I know it's a null because I traced it into the debugger. I tried with either int or char, I got the same result.

– Vincent Hubert
Aug 10 '18 at 18:52

1

This is apparently a problem in some versions of Windows SDK, see developercommunity.visualstudio.com/content/problem/247770/…

– n.m.
Aug 10 '18 at 18:55

1

@AlanBirtles: it works for me in Debug mode but fails in Release mode. Same behavior as OP.

– Thomas Weller
Aug 10 '18 at 18:55

|
show 3 more comments

When I use getch, it always appends the caracter read with a null character.

When I use the following code:

#include "stdafx.h"

#include <conio.h>



int main()

{

    char c = 0;



    while (c != 'x')

    {

        c = _getch();

        printf("Char read: <%c> n", c);

    }

}

It returns the follwing on the console, when I press the keys "asdx":

Char read: <a>

Char read: < >

Char read: <s>

Char read: < >

Char read: <d>

Char read: < >

Char read: <x>

This is compiled in VS 2017 in a plain new single file project, running on a windows 10 console window. I tried removing the _UNICODE and UNICODE define.

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

How do you know it's a null character? BTW _getch() returns int.

– n.m.
Aug 10 '18 at 18:48

2

works as expected for me, have you tried printing the numerical value of c to see what it is?

– Alan Birtles
Aug 10 '18 at 18:48

I know it's a null because I traced it into the debugger. I tried with either int or char, I got the same result.

– Vincent Hubert
Aug 10 '18 at 18:52

1

This is apparently a problem in some versions of Windows SDK, see developercommunity.visualstudio.com/content/problem/247770/…

– n.m.
Aug 10 '18 at 18:55

1

@AlanBirtles: it works for me in Debug mode but fails in Release mode. Same behavior as OP.

– Thomas Weller
Aug 10 '18 at 18:55

|
show 3 more comments

When I use getch, it always appends the caracter read with a null character.

When I use the following code:

#include "stdafx.h"

#include <conio.h>



int main()

{

    char c = 0;



    while (c != 'x')

    {

        c = _getch();

        printf("Char read: <%c> n", c);

    }

}

It returns the follwing on the console, when I press the keys "asdx":

Char read: <a>

Char read: < >

Char read: <s>

Char read: < >

Char read: <d>

Char read: < >

Char read: <x>

This is compiled in VS 2017 in a plain new single file project, running on a windows 10 console window. I tried removing the _UNICODE and UNICODE define.

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

When I use getch, it always appends the caracter read with a null character.

When I use the following code:

#include "stdafx.h"

#include <conio.h>



int main()

{

    char c = 0;



    while (c != 'x')

    {

        c = _getch();

        printf("Char read: <%c> n", c);

    }

}

It returns the follwing on the console, when I press the keys "asdx":

Char read: <a>

Char read: < >

Char read: <s>

Char read: < >

Char read: <d>

Char read: < >

Char read: <x>

This is compiled in VS 2017 in a plain new single file project, running on a windows 10 console window. I tried removing the _UNICODE and UNICODE define.

c++ visual-studio-2017 console-application

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

asked Aug 10 '18 at 18:40

Vincent Hubert

1,161819

How do you know it's a null character? BTW _getch() returns int.

– n.m.
Aug 10 '18 at 18:48

2

works as expected for me, have you tried printing the numerical value of c to see what it is?

– Alan Birtles
Aug 10 '18 at 18:48

I know it's a null because I traced it into the debugger. I tried with either int or char, I got the same result.

– Vincent Hubert
Aug 10 '18 at 18:52

1

This is apparently a problem in some versions of Windows SDK, see developercommunity.visualstudio.com/content/problem/247770/…

– n.m.
Aug 10 '18 at 18:55

1

@AlanBirtles: it works for me in Debug mode but fails in Release mode. Same behavior as OP.

– Thomas Weller
Aug 10 '18 at 18:55

|
show 3 more comments

How do you know it's a null character? BTW _getch() returns int.

– n.m.
Aug 10 '18 at 18:48

2

works as expected for me, have you tried printing the numerical value of c to see what it is?

– Alan Birtles
Aug 10 '18 at 18:48

I know it's a null because I traced it into the debugger. I tried with either int or char, I got the same result.

– Vincent Hubert
Aug 10 '18 at 18:52

1

This is apparently a problem in some versions of Windows SDK, see developercommunity.visualstudio.com/content/problem/247770/…

– n.m.
Aug 10 '18 at 18:55

1

@AlanBirtles: it works for me in Debug mode but fails in Release mode. Same behavior as OP.

– Thomas Weller
Aug 10 '18 at 18:55

How do you know it's a null character? BTW _getch() returns int.

– n.m.
Aug 10 '18 at 18:48

works as expected for me, have you tried printing the numerical value of c to see what it is?

– Alan Birtles
Aug 10 '18 at 18:48

I know it's a null because I traced it into the debugger. I tried with either int or char, I got the same result.

– Vincent Hubert
Aug 10 '18 at 18:52

This is apparently a problem in some versions of Windows SDK, see developercommunity.visualstudio.com/content/problem/247770/…

– n.m.
Aug 10 '18 at 18:55

@AlanBirtles: it works for me in Debug mode but fails in Release mode. Same behavior as OP.

– Thomas Weller
Aug 10 '18 at 18:55

|
show 3 more comments

2 Answers
2

active

oldest

votes

Well, crap!

It's a (rather new) bug in windows.

https://developercommunity.visualstudio.com/content/problem/247770/-getch-broken-in-vs-157.html

"When building a console application using the _getch() function
suddenly returns two times for each keypress"

got the following response from microsoft:

" Thanks for reporting this! This will be fixed on a future windows
update."

UPDATE:
As stated in the link above, setting the runtime to statically link with a previous version of the C runtime will fix the issue, but you need to make sure all your related projects (if you are building a library, for example) also use the same runtime. (I tested it)

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

add a comment |

If you don't want to (or you can't) use a previous version of the Universal C Runtime, you can use _getwch instead of _getch, as the problem doesn't affect to _getwch function.

Note that _getwch can return Unicode characters, so it may return distinct values than _getch for some keys. For example, for € character, _getch returns 0x3f (?) while _getwch returns 0x20ac (Unicode value for €)

answered Oct 30 '18 at 12:53

gusitoguay

1106

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

Well, crap!

It's a (rather new) bug in windows.

https://developercommunity.visualstudio.com/content/problem/247770/-getch-broken-in-vs-157.html

"When building a console application using the _getch() function
suddenly returns two times for each keypress"

got the following response from microsoft:

" Thanks for reporting this! This will be fixed on a future windows
update."

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

add a comment |

Well, crap!

It's a (rather new) bug in windows.

https://developercommunity.visualstudio.com/content/problem/247770/-getch-broken-in-vs-157.html

"When building a console application using the _getch() function
suddenly returns two times for each keypress"

got the following response from microsoft:

" Thanks for reporting this! This will be fixed on a future windows
update."

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

add a comment |

Well, crap!

It's a (rather new) bug in windows.

https://developercommunity.visualstudio.com/content/problem/247770/-getch-broken-in-vs-157.html

"When building a console application using the _getch() function
suddenly returns two times for each keypress"

got the following response from microsoft:

" Thanks for reporting this! This will be fixed on a future windows
update."

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

Well, crap!

It's a (rather new) bug in windows.

https://developercommunity.visualstudio.com/content/problem/247770/-getch-broken-in-vs-157.html

"When building a console application using the _getch() function
suddenly returns two times for each keypress"

got the following response from microsoft:

" Thanks for reporting this! This will be fixed on a future windows
update."

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

edited Aug 10 '18 at 19:29

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

answered Aug 10 '18 at 18:56

Vincent Hubert

1,161819

add a comment |

If you don't want to (or you can't) use a previous version of the Universal C Runtime, you can use _getwch instead of _getch, as the problem doesn't affect to _getwch function.

answered Oct 30 '18 at 12:53

gusitoguay

1106

add a comment |

If you don't want to (or you can't) use a previous version of the Universal C Runtime, you can use _getwch instead of _getch, as the problem doesn't affect to _getwch function.

answered Oct 30 '18 at 12:53

gusitoguay

1106

add a comment |

If you don't want to (or you can't) use a previous version of the Universal C Runtime, you can use _getwch instead of _getch, as the problem doesn't affect to _getwch function.

answered Oct 30 '18 at 12:53

gusitoguay

1106

If you don't want to (or you can't) use a previous version of the Universal C Runtime, you can use _getwch instead of _getch, as the problem doesn't affect to _getwch function.

answered Oct 30 '18 at 12:53

gusitoguay

1106

answered Oct 30 '18 at 12:53

gusitoguay

1106

answered Oct 30 '18 at 12:53

gusitoguay

1106

answered Oct 30 '18 at 12:53

gusitoguay

1106

add a comment |

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