fgets() not working in a function [duplicate]

Question

I am writing a program which uses fgets() to scan a 3 Char long string as an Airport code for Departure and arrival. When I write the statement outside its method (in the main) it works fine however inside it does not wait for input and leaves the variables blank.

void newFlight ()
    {
        printf("\n");
        printf("============= CREATE A NEW FLIGHT ============= \n");
        printf("Type 0 at any point to exit to main menu. \n");
        printf("\n");

        printf("EnterFlight ID (0 to cancel) : ");
        scanf("%d", &flyList[curFly].flightID);

        char codeA [4];
        printf ("Enter Destination (Airport Code): ");
        fgets(codeA, 3, stdin);
        strcpy(codeA, flyList[curFly].arrive);
        printf("%s   %s \n", codeA, flyList[curFly].arrive);  //TEST

        printf("Enter Place Of Departure: ");
        char codeD[4];
        scanf("%s", codeD);
        strcpy(codeD, flyList[curFly].depart);
        printf("%s   %s \n", codeD, flyList[curFly].depart);  //TEST

        printf("Enter Date Of Departure (DD MM YYYY): ");
        scanf("%hd %hd %hd", &flyList[curFly].timeOfDep.day, &flyList[curFly].timeOfDep.month, &flyList[curFly].timeOfDep.year);

        printf("Enter Time Of Departure (HH MM)in 24Hr Format: ");
        scanf("%hd %hd", &flyList[curFly].timeOfDep.hour, &flyList[curFly].timeOfDep.minute);       

        curFly++;
    }

Answer 1

Mixing fgets() with scanf() is problematic.

fgets() consumes the Enter (\n).
scanf("%d", ... sees the \n, which stops the %d conversion, and puts \n back into stdin for the next IO operation - which happend to be OP's fgets() which returns promptly with a short string.

Also need to check scanf() results. specifying a width with "%s is good, like "%3s.

Quick solution: only using scanf()

 //  scanf("%d", &flyList[curFly].flightID);
if (1 != scanf("%d", &flyList[curFly].flightID)) handle_error();
 ...
char codeA [4];
// fgets(codeA, 3, stdin);
if (1 != scanf("%3s", codeA) handle_error();
...
// Likely backwards
// strcpy(codeA, flyList[curFly].arrive);
strcpy(flyList[curFly].arrive, codeA);
...
char codeD[4];
// scanf("%3s", codeD);
if (1 != scanf("%3s", codeD)) handle_error();
...
// scanf("%hd %hd %hd", &flyList[curFly].timeOfDep.day, &flyList ...
if (3 != scanf("%hd %hd %hd", &flyList[curFly].timeOfDep.day, &flyList[curFly].timeOfDep.month, &flyList[curFly].timeOfDep.year)) handle_error();
...
// scanf("%hd %hd", &flyList[curFly].timeOfDep.hour, &flyList ...
if (2 != scanf("%hd %hd", &flyList[curFly].timeOfDep.hour, &flyList[curFly].timeOfDep.minute)) handle_error();

Better solution: use fgets()/sscanf()

 //  scanf("%d", &flyList[curFly].flightID);
char buf[100];
if (fgets(buf, sizeof buf, stdin) == NULL) Handle_EOForIOError();
if (1 != sscanf(buf, "%d", &flyList[curFly].flightID)) handle_parse_error();
... 
if (fgets(buf, sizeof buf, stdin) == NULL) Handle_EOForIOError();
if (1 != sscanf(buf, "%3s", flyList[curFly].arrive) handle_parse_error();
...
etc.

BTW: scanf() format "%hd %hd" and "%hd%hd" do the same thing.