arrays - C Null character causing problems with program behaviour

Question

The problem I am having is that this program is menu driven. When I enter the letter "i" is inputted in the input array which has a size of MAX_LENGTH+1. Through GDB I found out that "i" is inputted in the 0th index of the input array and the rest of the spaces are inputted with the NULL_CHAR character. Anyways when I press "i" for the insert menu, I have greeted by a field which tells me to enter a value. I enter any integer and press inter. Instead of being greeted by the "Command?:" field and give me a chance to put an entry, it immediately tells me that my input is invalid and tells me to enter a command again. Here is what I mean:

Commands are I (insert), D (delete), S (search by name),
  V (search by value), P (print), Q (quit).

Command?: i
45

Command?: 
Invalid command.
Commands are I (insert), D (delete), S (search by name),
  V (search by value), P (print), Q (quit).


Command?: 

I found out that the reason this is happening is because when the safegets function is called again, for some reason the local variable c in the function safegets has a value of NULL_CHAR, presumably from the fact that all the other values in the input char array had all other entries as NULL_CHAR. I do not understand why c is automatically assigned the value of NULL_CHAR because in the while loop, because there's a statement c = getchar() that should be asking for my input again. But for some reason after every entry, c's default value becomes NULL_CHAR and asks you for your input the next time safegets is called.

Here is my what I want my output to be like:

Commands?are?I?(insert),?D?(delete),?S?(search?by?name),?
??V?(search?by?value),?P?(print),?Q?(quit).?
?
Command?:?I?
??value:?50000?
?
Command?:?I
  value: 

Here is the main function:

const int MAX_LENGTH = 1023;
const char NULL_CHAR = '';
const char NEWLINE = '
';


    int main (void)
    { 
        const char bannerString[]
            = "Personal Team Maintenance Program.

";
        const char commandList[]
            = "Commands are I (insert), D (delete), S (search by name),
"
              "  V (search by value), P (print), Q (quit).
";

        // Declare linked list head.
        //   ADD STATEMENT(S) HERE TO DECLARE LINKED LIST HEAD.


        // announce start of program
        printf("%s",bannerString);
        printf("%s",commandList);

        char response;
        char input[MAX_LENGTH+1];
        int value;
        do
        {
            printf("
Command?: ");
            safegets(input,MAX_LENGTH+1);
            // Response is first char entered by user.
            // Convert to uppercase to simplify later comparisons.
            response = toupper(input[0]);

            if (response == 'I')
            {
                // Insert a player entry into the linked list.
                // Maintain the list in correct order (G, D, M, S).
                //   ADD STATEMENT(S) HERE

                // USE THE FOLLOWING PRINTF STATEMENTS WHEN PROMPTING FOR DATA:
                // printf("  family name: ");
                // printf("  first name: ");
                // printf("  position: ");
                   printf(" value: ");
                   scanf("%d", value);






            }
            else if (response == 'D')
            {
                // Delete a player from the list.

                printf("
Enter family name for entry to delete: ");

                //   ADD STATEMENT(S) HERE

            }
            else if (response == 'S')
            {
                // Search for a player by family name.

                printf("
Enter family name to search for: ");

                //   ADD STATEMENT(S) HERE

            }
            else if (response == 'V')
            {
                // Search for players that are worth less than or equal a value.

                printf("
Enter value: ");

                //   ADD STATEMENT(S) HERE

            }
            else if (response == 'P')
            {
                // Print the team.

                //   ADD STATEMENT(S) HERE

            }
            else if (response == 'Q')
            {
                ; // do nothing, we'll catch this case below
            }
            else 
            {
                // do this if no command matched ...
                printf("
Invalid command.
%s
",commandList);
            }
        } while (response != 'Q');

        // Delete the whole linked list that hold the team.
        //   ADD STATEMENT(S) HERE


        // Print the linked list to confirm deletion.
        //   ADD STATEMENT(S) HERE


        return 0;
    }

Helper function being called:

void safegets (char s[], int arraySize)
{
    int i = 0, maxIndex = arraySize-1;
    char c;
    while (i < maxIndex && (c = getchar()) != NEWLINE)
    {
        s[i] = c;
        i = i + 1;
    }
    s[i] = NULL_CHAR;
}

Answer 1

Your code is fine. You need to change

scanf("%d", value); 
//          ^Place & before the argument value because scanf expect pointer as its argument

to

scanf("%d", &value);