C input routine for single character and string

By answering some beginner questions in the programming forum, I am trying to learn some C/C++ again. As a matter of course, I learned something new as always, this is a page I referred to when trying to clear the buffer in stdin.

The first example is for capturing single character and check if it is a number between 1 and 4:

char option;
int number;
do {
    puts("Please enter your choice:");
    fflush(stdout);
    if (fgets(&option, 2, stdin) != NULL) {
        if (option != '\n') {
            scanf("%*[^\n]"); // get rid of the non-newline characters
            scanf("%*c");     // get rid of the newline character
        }
    }
} while (!(sscanf(&option, "%d", &number) == 1 &&
           number >= 1 && number <= 4));

The 2nd example is for capturing a string with trimming, overflow protection and emptyness checking:

char fileStr[20];
char *pointer = fileStr;
bool tooLong = false;

do {
    printf("\nPlease input a file name: ");
    fflush(stdout);
    if (fgets(fileStr, sizeof fileStr, stdin) != NULL) {
        tooLong = false;
        if (*fileStr != '\n') {
            // search for newline character
            char *newline = strchr(fileStr, '\n');
            if (newline != NULL) {
                *newline = '\0'; /* overwrite trailing newline */
                pointer = trimwhitespace(pointer); /* trim the line */
            } else {
                /* clear the stdin since user input too much */
                tooLong = true;
                scanf("%*[^\n]");
                scanf("%*c");
            }
        }
    }
} while (tooLong || *pointer == '\0' || *pointer == '\n');

printf("file name = \"%s\"\n", pointer);

Pay special attention on the variable you are gonna use at last, it is "pointer".