Implementation status: partially implemented


#include <stdio.h>

char *fgets(char *str, int n, FILE *stream);


The function reads a line from the specified stream and stores it into the string pointed to by str.
It stops when either:

  • (n-1) characters are read,
  • the newline character is read,
  • the end-of-file is reached,

whichever comes first.

str - the result string,
n - the maximum number of characters to be read,
stream - the input stream.

A null byte is written after the last byte read into the array. If the end-of-file condition is encountered before any bytes are read, the contents of the array pointed to by str not changed.

Return value

Upon successful completion, fgets() returns str.

If the stream is at end-of-file, the end-of-file indicator for the stream is set and fgets() returns a null pointer. If a read error occurs, the error indicator for the stream is set, fgets() returns a null pointer and sets errno to indicate the error.


[EAGAIN] The O_NONBLOCK flag is set for the file descriptor underlying stream and the thread would be delayed in the fgetc() operation.
[EBADF] The file descriptor underlying stream is not a valid file descriptor open for reading.
[EINTR] The read operation was terminated due to the receipt of a signal, and no data was transferred.
[EIO] A physical I/O error has occurred, or the process is in a background process group attempting to read from its controlling terminal, and either the calling thread is blocking SIGTTIN or the process is ignoring SIGTTIN or the process group of the process is orphaned.
[EOVERFLOW] The file is a regular file and an attempt was made to read at or beyond the offset maximum associated with the corresponding stream.
[ENOMEM] Insufficient storage space is available.
[ENXIO] A request was made of a nonexistent device, or the request was outside the capabilities of the device.

Implementation tasks

  • Implement error handling for the function.