Item Value
Header filestdio.h
Declarationint ungetc(int ch, FILE *stream);
FunctionPut the character ch back to the input stream stream. This character will be obtained by the next read operation on stream.
Returnreturns ch on success or EOF on failure.
A call to fflush(), fseek(), or rewind() discards the character.
You may not unget an EOF.
#include
int main ()
{
FILE * fp;
int c;
char buffer [256];
fp = fopen ("test.txt","rt");
if (fp==NULL)
perror ("Error opening file");
else {
while (!feof (fp))
{
c=getc (fp);
if (c == '#')
ungetc ('@',fp);
else
ungetc (c,fp);
fgets (buffer,255,fp);
fputs (buffer,stdout);
}
}
return 0;
}