Using scanf to accept user input

Question

gcc 4.4.2

I was reading an article about scanf. I personally have never checked the return code of a scanf.

#include 

int main(void)
         


        

Answer 1

scanf() has problems, in that if a user is expected to type an integer, and types a string instead, often the program bombs. This can be overcome by reading all input as a string (use getchar()), and then converting the string to the correct data type.

/* example one, to read a word at a time */
#include 
#include 
#define MAXBUFFERSIZE   80

void cleartoendofline( void );  /* ANSI function prototype */

void cleartoendofline( void )
{
    char ch;
    ch = getchar();
    while( ch != '\n' )
        ch = getchar();
}

main()
{
    char    ch;                     /* handles user input */
    char    buffer[MAXBUFFERSIZE];  /* sufficient to handle one line */
    int     char_count;             /* number of characters read for this line */
    int     exit_flag = 0;
    int     valid_choice;

    while( exit_flag  == 0 ) {
        printf("Enter a line of text (<80 chars)\n");
        ch = getchar();
        char_count = 0;
        while( (ch != '\n')  &&  (char_count < MAXBUFFERSIZE)) {
            buffer[char_count++] = ch;
            ch = getchar();
        }
        buffer[char_count] = 0x00;      /* null terminate buffer */
        printf("\nThe line you entered was:\n");
        printf("%s\n", buffer);

        valid_choice = 0;
        while( valid_choice == 0 ) {
            printf("Continue (Y/N)?\n");
            scanf(" %c", &ch );
            ch = toupper( ch );
            if((ch == 'Y') || (ch == 'N') )
                valid_choice = 1;
            else
                printf("\007Error: Invalid choice\n");
            cleartoendofline();
        }
        if( ch == 'N' ) exit_flag = 1;
    }
}