How do I flush the cin buffer

Question

How do I clear the cin buffer in C

User · Answer

int i    cout  lt  lt   Please enter an integer value           cin  gt  gt  i  leaves   n  among possible other junk in the buffer          n  also happens to be the default delim character for getline   below    cin  gt  gt  i     if  cin fail             cout  lt  lt    ncin failed - substituting  i 1  n n       i   1        cin clear    cin ignore INT MAX   n        cout  lt  lt   The value you entered is     lt  lt  i  lt  lt    and its double is    lt  lt  i 2  lt  lt     n n      string myString    cout  lt  lt   What s your full name   spaces inclded   n     getline  cin  myString     cout  lt  lt    nHello     lt  lt  myString  lt  lt      n n n

User · Answer

cin clear    fflush stdin     This was the only thing that worked for me when reading from console  In every other case it would either read indefinitely due to lack of  n  or something would remain in the buffer   EDIT  I found out that the previous solution made things worse  THIS one however  works   cin getline temp  STRLEN   if  cin fail          cin clear        cin ignore numeric limits lt streamsize gt   max      n

User · Answer

I prefer   cin clear    fflush stdin     There s an example where cin ignore just doesn t cut it  but I can t think of it at the moment  It was a while ago when I needed to use it  with Mingw    However  fflush stdin  is undefined behavior according to the standard  fflush   is only meant for output streams  fflush stdin  only seems to work as expected on Windows  with GCC and MS compilers at least  as an extension to the C standard   So  if you use it  your code isn t going to be portable   See Using fflush stdin    Also  see http   ubuntuforums org showpost php s 9129c7bd6e5c8fd67eb332126b59b54c amp p 452568 amp postcount 1 for an alternative

User · Answer

It worked for me  I have used for loop with getline      cin ignore

User · Answer

Possibly   std  cin ignore INT MAX     This would read in and ignore everything until EOF   you can also supply a second argument which is the character to read until  ex    n  to ignore a single line    Also  You probably want to do a  std  cin clear    before this too to reset the stream state

User · Answer

I would prefer the C   size constraints over the C versions      Ignore to the end of file cin ignore std  numeric limits lt std  streamsize gt   max        Ignore to the end of line cin ignore std  numeric limits lt std  streamsize gt   max      n

User · Answer

include  lt stdio ext h gt    and then use function     fpurge stdin

User · Answer

I prefer   cin clear    fflush stdin     There s an example where cin ignore just doesn t cut it  but I can t think of it at the moment  It was a while ago when I needed to use it  with Mingw    However  fflush stdin  is undefined behavior according to the standard  fflush   is only meant for output streams  fflush stdin  only seems to work as expected on Windows  with GCC and MS compilers at least  as an extension to the C standard   So  if you use it  your code isn t going to be portable   See Using fflush stdin    Also  see http   ubuntuforums org showpost php s 9129c7bd6e5c8fd67eb332126b59b54c amp p 452568 amp postcount 1 for an alternative

User · Answer

cin clear    fflush stdin     This was the only thing that worked for me when reading from console  In every other case it would either read indefinitely due to lack of  n  or something would remain in the buffer   EDIT  I found out that the previous solution made things worse  THIS one however  works   cin getline temp  STRLEN   if  cin fail          cin clear        cin ignore numeric limits lt streamsize gt   max      n

User · Answer

Possibly   std  cin ignore INT MAX     This would read in and ignore everything until EOF   you can also supply a second argument which is the character to read until  ex    n  to ignore a single line    Also  You probably want to do a  std  cin clear    before this too to reset the stream state

User · Answer

The following should work   cin flush      On some systems it s not available and then you can use   cin ignore INT MAX

User · Answer

Another possible  manual  solution is  cin clear    while  cin get        n          continue      I cannot use fflush or cin flush   with CLion so this came handy

User · Answer

include  lt stdio ext h gt    and then use function     fpurge stdin

User · Answer

How about   cin ignore cin rdbuf  - gt in avail

User · Answer

I would prefer the C   size constraints over the C versions      Ignore to the end of file cin ignore std  numeric limits lt std  streamsize gt   max        Ignore to the end of line cin ignore std  numeric limits lt std  streamsize gt   max      n

User · Answer

I have found two solutions to this   The first  and simplest  is to use std  getline   for example   std  getline std  cin  yourString         that will discard the input stream when it gets to a new-line  Read more about this function here   Another option that directly discards the stream is this      include  lt limits gt     Possibly some other code here cin clear    cin ignore numeric limits lt streamsize gt   max      n      Good luck

User · Answer

Possibly   std  cin ignore INT MAX     This would read in and ignore everything until EOF   you can also supply a second argument which is the character to read until  ex    n  to ignore a single line    Also  You probably want to do a  std  cin clear    before this too to reset the stream state

User · Answer

It worked for me  I have used for loop with getline      cin ignore

User · Answer

Another possible  manual  solution is  cin clear    while  cin get        n          continue      I cannot use fflush or cin flush   with CLion so this came handy

User · Answer

I prefer   cin clear    fflush stdin     There s an example where cin ignore just doesn t cut it  but I can t think of it at the moment  It was a while ago when I needed to use it  with Mingw    However  fflush stdin  is undefined behavior according to the standard  fflush   is only meant for output streams  fflush stdin  only seems to work as expected on Windows  with GCC and MS compilers at least  as an extension to the C standard   So  if you use it  your code isn t going to be portable   See Using fflush stdin    Also  see http   ubuntuforums org showpost php s 9129c7bd6e5c8fd67eb332126b59b54c amp p 452568 amp postcount 1 for an alternative

User · Answer

cin get   seems to flush it automatically oddly enough  probably not preferred though  since this is confusing and probably temperamental

User · Answer

Possibly   std  cin ignore INT MAX     This would read in and ignore everything until EOF   you can also supply a second argument which is the character to read until  ex    n  to ignore a single line    Also  You probably want to do a  std  cin clear    before this too to reset the stream state

User · Answer

I have found two solutions to this   The first  and simplest  is to use std  getline   for example   std  getline std  cin  yourString         that will discard the input stream when it gets to a new-line  Read more about this function here   Another option that directly discards the stream is this      include  lt limits gt     Possibly some other code here cin clear    cin ignore numeric limits lt streamsize gt   max      n      Good luck

User · Answer

The following should work   cin flush      On some systems it s not available and then you can use   cin ignore INT MAX

User · Answer

How about   cin ignore cin rdbuf  - gt in avail

User · Answer

int i    cout  lt  lt   Please enter an integer value           cin  gt  gt  i  leaves   n  among possible other junk in the buffer          n  also happens to be the default delim character for getline   below    cin  gt  gt  i     if  cin fail             cout  lt  lt    ncin failed - substituting  i 1  n n       i   1        cin clear    cin ignore INT MAX   n        cout  lt  lt   The value you entered is     lt  lt  i  lt  lt    and its double is    lt  lt  i 2  lt  lt     n n      string myString    cout  lt  lt   What s your full name   spaces inclded   n     getline  cin  myString     cout  lt  lt    nHello     lt  lt  myString  lt  lt      n n n

User · Answer

cin get   seems to flush it automatically oddly enough  probably not preferred though  since this is confusing and probably temperamental

User · Answer

The following should work   cin flush      On some systems it s not available and then you can use   cin ignore INT MAX

User · Answer

I would prefer the C   size constraints over the C versions      Ignore to the end of file cin ignore std  numeric limits lt std  streamsize gt   max        Ignore to the end of line cin ignore std  numeric limits lt std  streamsize gt   max      n

User · Answer

Easiest way   cin seekg 0 ios  end   cin clear      It just positions the cin pointer at the end of the stdin stream and cin clear   clears all error flags such as the EOF flag

User · Answer

I prefer   cin clear    fflush stdin     There s an example where cin ignore just doesn t cut it  but I can t think of it at the moment  It was a while ago when I needed to use it  with Mingw    However  fflush stdin  is undefined behavior according to the standard  fflush   is only meant for output streams  fflush stdin  only seems to work as expected on Windows  with GCC and MS compilers at least  as an extension to the C standard   So  if you use it  your code isn t going to be portable   See Using fflush stdin    Also  see http   ubuntuforums org showpost php s 9129c7bd6e5c8fd67eb332126b59b54c amp p 452568 amp postcount 1 for an alternative

User · Answer

Easiest way   cin seekg 0 ios  end   cin clear      It just positions the cin pointer at the end of the stdin stream and cin clear   clears all error flags such as the EOF flag

User · Answer

I would prefer the C   size constraints over the C versions      Ignore to the end of file cin ignore std  numeric limits lt std  streamsize gt   max        Ignore to the end of line cin ignore std  numeric limits lt std  streamsize gt   max      n

User · Answer

The following should work   cin flush      On some systems it s not available and then you can use   cin ignore INT MAX

[c++] How do I flush the cin buffer?

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