Programming in C

474 Appendix B The Standard C Library

Included in this file are declarations for the I/O functions and definitions for the names

EOF,NULL,stdin,stdout,stderr(all constant values), and FILE.

In the descriptions that follow,fileName,fileName1,fileName2,accessMode, and

formatare pointers to null-terminated strings,bufferis a pointer to a character array,

filePtris of type “pointer to FILE,”nand sizeare positive integer values of type

size_t,and iand care of type int.

void clearerr (filePtr)

Clears the end of file and error indicators associated with the file identified by

filePtr.

int fclose (filePtr)

Closes the file identified by filePtrand returns zero if the close is successful, or

returns EOFif an error occurs.

int feof (filePtr)

Returns nonzero if the identified file has reached the end of the file and returns zero

otherwise.

int ferror (filePtr)

Checks for an error condition on the indicated file and returns zero if an error exists,

and returns nonzero otherwise.

int fflush (filePtr)

Flushes (writes) any data from internal buffers to the indicated file, returning zero on

success and the value EOFif an error occurs.

int fgetc (filePtr)

Returns the next character from the file identified by filePtr, or the value EOFif an

end-of-file condition occurs. (Remember that this function returns an int.)

int fgetpos (filePtr, fpos)

Gets the current file position for the file associated with filePtr, storing it into the

fpos_t(defined in <stdio.h>) variable pointed to by fpos.fgetposreturns zero on

success, and returns nonzero on failure. See also the fsetposfunction.

char *fgets (buffer, i, filePtr)

Reads characters from the indicated file, until either i– 1 characters are read or a

newline character is read, whichever occurs first. Characters that are read are stored

into the character array pointed to by buffer. If a newline character is read, it willbe

stored in the array. If an end of file is reached or an error occurs, the value NULLis

returned; otherwise,bufferis returned.

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