Insert in alphabetical order by name in a linked list

Question

#define _CRT_SECURE_NO_WARNINGS
#define PAUSE system("pause")
#define CLS system ("cls")
#define FLUSH myFlush();
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include <ctype.h>
#include<time.h>

//Function Prototypes
void displayMenu();
int getChoice(int* option);
void myFlush();

typedef struct personType 
{
    char name[100];
    int age;
    float weight;
    struct personType* next; //pointer next points
}Person; //to the next node

typedef Person* LIST; //pointer to struct STUDENT named LIST

main() {
    LIST temp = NULL, start = NULL, linkedList = NULL; //declare to variable of type LIST
    int ageTemp = 0, count = 1, counter;
    char nameTemp[100], response;
    float weightTemp;
    int option;
    do {
        getChoice(&option);
        switch (option) //begin switch
        {
        case 1:
            do 
            {
                CLS;
                printf("\nEnter a name for person %d : ", count);
                scanf("%[^\t\n]", &nameTemp); FLUSH;

                printf("\nEnter the age for %s: ", nameTemp);
                scanf("%i", &ageTemp); FLUSH;

                printf("\nEnter the weight for %s: ", nameTemp);
                scanf("%f", &weightTemp); FLUSH;

                if (count == 1) 
                {
                    // create a node and store the information
                    // create the head of the list
                    linkedList = (LIST)malloc(sizeof(Person));
                    start = linkedList; // store the top/head/start of the list
                    strcpy(start->name, nameTemp);
                    start->age = ageTemp;
                    start->weight = weightTemp;
                    start->next = NULL;
                }
                else 
                {
                    temp = (LIST)malloc(sizeof(Person)); // create address of next node
                    linkedList->next = temp; // assign next pointer in STUDENT struct the address of next node
                    linkedList = temp;
                    strcpy(temp->name, nameTemp);
                    temp->age = ageTemp;
                    temp->weight = weightTemp;
                    temp->next = NULL;
                }

                printf("\nWould you like to enter another person?");
                printf("\nEnter Y/N: ");
                scanf("%c", &response); FLUSH;

                count++;
            } while (response == 'Y' || response == 'y');
            CLS;
            break;
        case 2:
            temp = start; // assigns temp to start
            // begin at the head of the list
            CLS;
            counter = 1;
            while (temp != NULL) //begin while
            { 
                printf("Student %i: %s\t Age: %2i Weight: %.2f \n",
                    counter, temp->name, temp->age, temp->weight);
                counter += 1;
                temp = temp->next; //iterates through the temp values
            } //end while
            printf("\n\n");
            PAUSE;
            CLS;
            break;
        case 3:
            printf("Exiting program...\n");
            printf("See you next time :)");
            break;
        default:
            CLS;
            printf("That was not a valid selection...");
            PAUSE;
        } // end Switch
    } while (option != 3);

    // Free The Memory
    while (start != NULL) //checks if start is pointing to null
    { 
        temp = start; // points temp node to where start is pointing
        start = start->next; // iterates to next node that start points to
        free(temp); // frees memory allocated for list
    } // endwhile
}// End of Main

void myFlush()
{
    while (getchar() != '\n');
}

void displayMenu()
{
    CLS;
    printf("Please select from the following options:\n\n");
    printf("1. Add a Record.\n");
    printf("2. Display All Records.\n");
    printf("3. Quit.\n\n\n");
    printf("Please enter a selection: ");
} // end of displayMenu

int getChoice(int* option)
{
    displayMenu();
    scanf("%i", &*option); FLUSH;
    return toupper(*option);
} // ends getChoice function

I don't know how to sort the linked list alphabetically. The linked list works fine on its own but I need to be able to insert a record of a person as the struct and list shows in the code but also alphabetically sort them so when I display the list it will show in that order. I would need to be able to set the head of the linked list if a person's name was to come before alphabetically the original head of the list. I have looked at other linked list posts but they do not help my problem in depth.

Answer 1

For starters the function main shall be declared like

int main( void )

Using the function toupper for an object of the type int that gets an integer

int getChoice(int* option)
{
    displayMenu();
    scanf("%i", &*option); FLUSH;
    return toupper(*option);
} //

does not make sense.

The call of scanf within the function can be written simpler

scanf("%d", option);

The second argument of this call of scanf

scanf("%[^\t\n]", &nameTemp);

shall be written like

scanf("%[^\t\n]", nameTemp);

Or it is better even to write

scanf("%99[^\n]", nameTemp);

The if-else statement in main after the case label 1: can be written the following way

// create a node and store the information
linkedList = malloc( sizeof( Person ) );
strcpy( linkedList->name, nameTemp );
linkedList->age = ageTemp;
linkedList->weight = weightTemp;

if ( start == NULL || strcmp( nameTemp, start->name ) < 0 ) 
{
    linkedList->next = start
    start = linkedList; // store the top/head/start of the list
}
else 
{
    temp = start;
    while ( temp->next != NULL && strcmp( nameTemp, temp->next->name ) >= 0 )
    {
        temp = temp->next;
    }

    linkedList->next = temp->next;
    temp->next = linkedList;  
}