Fwrite and fread return value from function

So, by giving -ve number, you have not see compiler warnings or use -Wall flag with gcc and you will get all the warnings. But, the result will not be what you expect it to!

Fwrite and fread return value from function

The argument mode points to a string beginning with one of the following sequences possibly followed by additional characters, as described below: The stream is positioned at the beginning of the file. The file is created if it does not exist, otherwise it is truncated.

Is it possible to write data to a text file using "fwrite" function in C

The file is created if it does not exist. The stream is positioned at the end of the file. The initial file position for reading is at the beginning of the file, but output is always appended to the end of the file.

Note that ANSI C requires that a file positioning function intervene between output and input, unless an input operation encounters end-of-file.

fwrite and fread return value from function

If this condition is not met, then a read is allowed to return the result of writes other than the most recent. Therefore it is good practice and indeed sometimes necessary under Linux to put an fseek 3 or fgetpos 3 operation between write and read operations on such a stream.

This operation may be an apparent no-op as in fseek Opening a file in append mode a as the first character of mode causes all subsequent write operations to this stream to occur at end-of-file, as if preceded the call: The file position indicator of the new stream is set to that belonging to fd, and the error and end-of-file indicators are cleared.

The result of applying fdopen to a shared memory object is undefined. The original stream if it exists is closed. The mode argument is used just as in the fopen function. If the pathname argument is a null pointer, freopen changes the mode of the stream to that specified in mode; that is, freopen reopens the pathname that is associated with the stream.

FD_SET(socket, fd)

In this case, the file descriptor associated with the stream need not be closed if the call to freopen succeeds. It is implementation-defined which changes of mode are permitted if anyand under what circumstances.

Otherwise, NULL is returned and errno is set to indicate the error. The fopenfdopen and freopen functions may also fail and set errno for any of the errors specified for the routine malloc 3.

The fopen function may also fail and set errno for any of the errors specified for the routine open 2. The fdopen function may also fail and set errno for any of the errors specified for the routine fcntl 2. The freopen function may also fail and set errno for any of the errors specified for the routines open 2fclose 3and fflush 3.size_t fread (void * ptr, size_t size, size_t count, FILE * stream); Read block of data from stream Reads an array of count elements, each one with a size of size bytes, from the stream and stores them in the block of memory specified by ptr.

count = fwrite(fid, A, precision, skip) includes an optional skip argument that specifies the number of bytes to skip before each precision value is written. With the skip argument present, fwrite skips and writes one value, skips and writes another value, etc., until all of A is written.

The fopen function does not read information from the file to determine the output value. example [filename,permission,machinefmt,encodingOut] = fopen(fileID) additionally returns the permission, machine format, and encoding that a previous call to fopen used when it opened the specified file.

size_t fwrite (const void * ptr, size_t size, size_t count, FILE * stream); Write block of data to stream Writes an array of count elements, each one with a size of size bytes, from the block of memory pointed by ptr to the current position in the stream.

Return value.

2 solutions

Number of objects read successfully, FILE * fp = fopen ("ashio-midori.com", "wb"); // must use binary mode fwrite The fread function See also. scanf fscanf sscanf scanf_s fscanf_s sscanf_s (C11) (C11) (C11) reads formatted input from stdin, a file stream or a buffer.

Usage — The PHP fread() function is used to do a binary-safe file reading. Return Value — This function returns the read string or FALSE on failure. It will stop at the end of the file or when it reaches the specified length, whichever comes first.

Relevant Functions — Other related PHP functions that you should know about are.

PHP : Function Reference : Filesystem Functions : fwrite PHP Examples Tutorials References