|
ungetc
int ungetc ( int character , FILE * stream ); | stdio.h |
| cplusplus.com |
Push a character back into stream.
A character is pushed into an input stream where last
character was read and the file pointer is reset to that previous
position.
This character will be returned by the next call to
getc or fread for
the same stream.
If the End-Of-File indicator was set is cleared after a call to this function.
A call to fflush,
fseek,
fsetpos
or rewind
for this stream
will undo the effects of any previous call to ungetc.
This function do not affect the file associated with the stream,
which will remain unchanged by any call to this function.
Parameters.
Return Value.
If successful, the character putted is returned.
Otherwise EOF is returned and the stream remains
unchanged.
Portability.
Defined in ANSI-C.
Example.
/* ungetc example */
#include <stdio.h>
main ()
{
FILE * pFile;
char c;
char buffer [256];
pFile = fopen ("myfile.txt","rt");
if (pFile==NULL) perror ("Error opening file");
else {
while (!feof (pFile))
{
c=fgetc (pFile);
ungetc (pFile)
fgets (buffer,255,pFile);
printf ("[%c] %s",c,buffer);
}
}
return 0;
}
This example opens an existing file called myfile.txt and reads the
first character of every line, then pushes back this character into the stream
and gets the whole line into buffer.
Output:
[T] This is a sample file
[c] called myfile.txt