C: input functions: why fgets(), not scanf()

--- tags: notes, c, functions --- # C: input functions: why fgets(), not scanf() last edition:2020/02/11 ## ```fgets()``` (recommended) **f** stands for file, **get** stands for requiring and **s** stands for string.\ This function is safer then `scanf(%s, str)` because the maximum size `n` is assigned in `fgets()`. 　 ### Declartion ```cmake=c char *fgets(char *str, int n, FILE *stream) ``` 　 ### Parameters * `char *str`This is the pointer to an array where the string read is stored. * `int n` This is the maximum number of characters to be read (including the final null-character). Usually, `n` is the length of `str`. * `FILE *stream` This is the pointer to a FILE object that identifies the stream where characters are read from. e.g. `stdin`. 　 ### Returns Value On success, the function returns the same `str` parameter. If the `EOF`(end of file) is encountered and no characters have been read, the contents of `str` remain unchanged and a `NULL` pointer is returned. If an error occurs, a `NULL` pointer is returned. 　 ### Behavior 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, or the end-of-file is reached, whichever comes first. When `FILE *stream=stdin` and the function returns non-NULL pointer, then `str` has the following contents:\ `str[]:o, o, o, o,... 10, 0, x, x, x...`\ where `o, o, o, o,...` are the characters read from the `FILE stream`; `10` is *line-feed* of ascii-code; `0` is null character `\0`; `x, x, x...` are the original contents in the `str[]`. 　 ## `scanf()` When reading ### Declartion ```cmake=c int scanf(const char *format, ...) ``` for reading string:`scanf("%s", &str)` 　 ### Parameters 　 ### Returns Value 　 ### Behavior