scanf stops working after first one [C] - c

Question

I am trying to have the user enter for the first, middle, and last name in my struct. The first scan works fine, any after that do not work. Here's my code so far
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include "contacts.h"
int main (void)
{
// Declare variables here:
struct Name names;
char yesNo;
// Display the title
printf("Contact Management System\n");
printf("-------------------------\n");
// Contact Name Input:
printf("Please enter the contact's first name: ");
scanf ("%d", &names.firstName);
printf("Do you want to enter a middle initial(s)? (y or n): ");
scanf(" %c", &yesNo);
while (yesNo == 'y' || yesNo == 'Y') {
printf("Please enter the contact's middle initial(s): ");
scanf(" %c%d", &names.middleInitial);
yesNo = 'n';
}
printf("Please enter the contact's last name: ");
scanf(" %c%d", &names.lastName);
Here's the struct in my header file
struct Name {
char firstName[31];
char middleInitial[7];
char lastName[36];
};
When I enter more than one character the program ends, when I enter just one character, the program skips the second scanf. I had the program working beforehand but I realized I needed to use structs so I switched from int's to the struct, and I haven't been able to make it work this way.

Answer 1

You are using scanf wrong.
scanf ("%d", &names.firstName);
names.firstName is a char array, but you are using %d which expects a
pointer to int, you are passing a pointer to an array. This is correct:
scanf("%30s", names.firstName);
Then you do
scanf(" %c%d", &names.middleInitial);
which has two errors: you are giving two conversion but passing only a on
pointer, and you are again passing the wrong pointer. Correct:
scanf("%6s", names.middleInitial);
and the same applies for scanf(" %c%d", &names.lastName);, the correct version
scanf("%35s", names.lastName);
In general, when using scanf with %s, you will have the problem that newline
and other strings are kept in the input buffer. This happens because %s
matches a sequence of non-white-space characters, so the newline (entered when
ENTER is pressed) will remain in the input buffer. Another example is
if the user enters two word separated by at least an empty space (like Hello Word),
%s would only read Hello. Subsequent calls of scanf may fail if they don't
anticipate this. That's why the best strategy is to clean the
buffer, use this function:
void clean_file_buffer(FILE *fp)
{
int c;
while((c = fgetc(fp)) != '\n' && c!=EOF);
}
And the you can use it like this:
printf("Please enter the contact's first name: ");
scanf ("%30s", names.firstName);
clean_file_buffer(stdin);
that takes care of left overs.
If you however want to have more control over the whole line, then you should
use fgets instead to read the whole line and then you can use sscanf to
parse it.

Answer 2

scanf("%s", names.firstName);
scanf(" %c", &yesNo);
scanf(" %s", names.middleInitial);
scanf(" %s", names.lastName);
or
scanf("%s", names.firstName);
getchar();
scanf("%c", &yesNo);
getchar();
scanf("%s", names.middleInitial);
getchar();
scanf("%s", names.lastName);
getchar();
and when yesNo question, if you typed over 1 character, first character will be into yesNo variable, and other chars will be into next input variable(names.middleInitial).
If you want to check the yesNo more carefully,
input yesNo as string. (but, buffer size check needed. buffer overflow.)
char yesNos[100];
scanf(" %s", &yesNos) ;
if ( yesNos[0]=='y' ) {...}