Reference
C Library
IOstream Library
Strings library
STL Containers
STL Algorithms
Miscellaneous
C Library
cassert (assert.h)
cctype (ctype.h)
cerrno (errno.h)
cfloat (float.h)
ciso646 (iso646.h)
climits (limits.h)
clocale (locale.h)
cmath (math.h)
csetjmp (setjmp.h)
csignal (signal.h)
cstdarg (stdarg.h)
cstddef (stddef.h)
cstdio (stdio.h)
cstdlib (stdlib.h)
cstring (string.h)
ctime (time.h)
cstdio (stdio.h)
functions:
clearerr
fclose
feof
ferror
fflush
fgetc
fgetpos
fgets
fopen
fprintf
fputc
fputs
fread
freopen
fscanf
fseek
fsetpos
ftell
fwrite
getc
getchar
gets
perror
printf
putc
putchar
puts
remove
rename
rewind
scanf
setbuf
setvbuf
sprintf
sscanf
tmpfile
tmpnam
ungetc
vfprintf
vprintf
vsprintf
macro constants:
EOF
FILENAME_MAX
NULL
TMP_MAX
objects:
stderr
stdin
stdout
types:
FILE
fpos_t
size_t


ferror

function
<cstdio>
int ferror ( FILE * stream );

Check error indicator

Checks if the error indicator associated with stream is set, returning a value different from zero if it is.
This indicator is generaly set by a previous operation on the stream that failed.

Parameters

stream
Pointer to a FILE object that identifies the stream.

Return Value

If the error indicator associated with the stream was set, the function returns a nonzero value.
Otherwise, it returns a zero value.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
 
/* ferror example: writing error */
#include <stdio.h>
int main ()
{
  FILE * pFile;
  pFile=fopen("myfile.txt","r");
  if (pFile==NULL) perror ("Error opening file");
  else {
    fputc ('x',pFile);
    if (ferror (pFile))
      printf ("Error Writing to myfile.txt\n");
    fclose (pFile);
  }
  return 0;
}


This program opens an existing file called myfile.txt in read-only mode but tries to write a character to it, generating an error that is detected by ferror.

Output:
Error Writing to myfile.txt

See also

feof Check End-of-File indicator (function)
clearerr Clear error indicators (function)
perror Print error message (function)