fgetln() - get a line from a stream
#include <stdio.h>
char * fgetln (FILE *stream, size_t *len)
The fgetln(3) function returns a pointer to the next line from the stream referenced by stream. This line is not a C string because it does not end with a terminating NUL character. The memory location pointed to by len contains the length of the line, including the final newline. (Note, however, that if the line is the last in a file that does not end in a newline, the returned text will not contain a newline.)
The fgetln(3) call returns a pointer after completing successfully; this pointer becomes invalid after the next I/O operation on stream (whether the operation is successful or not) or as soon as the stream is closed. Otherwise, the function returns NULL.
The fgetln(3) function does not distinguish between end-of-file and error; use the routines feof(3) and ferror(3) to determine which occurred. If an error occurs, the global veriable errno is set to indicate the error. The end-of-file condition is remembered (even on a terminal), and all subsequent attempts to read will return NULL until the condition is cleared with clearerr(3).
You may modify the text to which the returned pointer points, provided that you make no changes beyond the returned size. (There is one exception: if the last line of the file does not end in a newline, fgetln(3) guarantees one byte past the returned size, for code which needs to nul-terminate the string.) Any changes are lost as soon as the pointer becomes invalid.
The fgetln(3) function may also fail and set errno for any of the errors specified for the routines fflush(3), malloc(3), read(2), stat(2), or realloc(3).
ferror(3)
fgets(3)
fopen(3)
putc(3)