IN C LANGUAGE: I've been trying to finish this program for the last few days, and I'm stuck on one part of it, and I can't figure out what to do. The goal is to read in a file (separated by commas), put the information into a linked list, and then sort that linked list by either first or last name using function pointers. Everything I have so far works, aside from the fact that my output is never sorted. I'm doing something wrong with the listSort function, and I don't know what it is. Can anyone please just take a look at what I have and offer a suggestion or solution? It might not even be an issue with the function itself, but something somewhere else. I would greatly appreciate it. Please do not make any changes to the variables in the structs. Month has to be a string, it cannot be an integer. driver.c: #include "functions.h" #include <stdio.h> #include <stdlib.h> #include <assert.h> #include <string.h> int main(int argc, char* argv[]) { //creating input and output files FILE* in = NULL; FILE* out = NULL; node_t* head = NULL; node_t* temp = NULL; //checking for 4 command line arguments assert(argc == 4); //opening input file in = fopen(argv[1], "r"); assert(in != NULL); //opening output file out = fopen(argv[2], "w"); assert(out != NULL); int sortBy = atoi(argv[4]); temp = createList(in, &head); if(sortBy == 1) { sortList(&head, compare_by_firstname); } else if(sortBy == 2) { sortList(&head, compare_by_lastname); } printList(out, temp); deleteList(&head); //closing files fclose(in); fclose(out); return 0; } functions.c: #include "functions.h" #include <stdio.h> #include <stdlib.h> #include <assert.h> #include <string.h> #include <stdbool.h> bool isLeapYear(int year) { if(year % 4 != 0) { return false; } else if(year % 100 != 0) { return true; } else if(year % 400 != 0) { return false; } else { return true; } } void printBorder(FILE* out) { int i = 0; for(i = 0; i < 80; i++) fprintf(out,"*"); fprintf(out, "\n"); } bool checkInvalidDate(node_t *node) { int year = (int)node->birthday.year; if(node->birthday.day < 1 || node->birthday.year < 1) { return true; } if(strcmp(node->birthday.month, "February") == 0) { if(isLeapYear(year)) { if(node->birthday.day > 29) { return true; } } else if(node->birthday.day > 28) { return true; } } else if((strcmp(node->birthday.month, "April") == 0) || (strcmp(node->birthday.month, "June") == 0) || (strcmp(node->birthday.month, "September") == 0) || (strcmp(node->birthday.month, "November") == 0)) { if(node->birthday.day > 30) { return true; } } else { if(node->birthday.day > 31) { return true; } } return false; } void add(node_t **node, node_t **head) { node_t* current = *head; while(current != NULL) { //comparing first and last names to check for duplicates; if duplicate the info isn't added to the list if((strcmp(current->firstName, (*node)->firstName) == 0) && (strcmp(current->lastName, (*node)->lastName) == 0)) { return; } current = current->next; } //adding information as a node to the list (*node.

1. IN C LANGUAGE: I've been trying to finish this program for the last few days, and I'm stuck
on one part of it, and I can't figure out what to do.
The goal is to read in a file (separated by commas), put the information into a linked list, and
then sort that linked list by either first or last name using function pointers.
Everything I have so far works, aside from the fact that my output is never sorted. I'm doing
something wrong with the listSort function, and I don't know what it is.
Can anyone please just take a look at what I have and offer a suggestion or solution? It might not
even be an issue with the function itself, but something somewhere else.
I would greatly appreciate it.
Please do not make any changes to the variables in the structs. Month has to be a string, it
cannot be an integer.
driver.c:
#include "functions.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
int main(int argc, char* argv[]) {
//creating input and output files
FILE* in = NULL;
FILE* out = NULL;
node_t* head = NULL;
node_t* temp = NULL;
//checking for 4 command line arguments
assert(argc == 4);
//opening input file
in = fopen(argv[1], "r");
assert(in != NULL);

2. //opening output file
out = fopen(argv[2], "w");
assert(out != NULL);
int sortBy = atoi(argv[4]);
temp = createList(in, &head);
if(sortBy == 1) {
sortList(&head, compare_by_firstname);
}
else if(sortBy == 2) {
sortList(&head, compare_by_lastname);
}
printList(out, temp);
deleteList(&head);
//closing files
fclose(in);
fclose(out);
return 0;
}
functions.c:
#include "functions.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

3. #include <string.h>
#include <stdbool.h>
bool isLeapYear(int year) {
if(year % 4 != 0) {
return false;
}
else if(year % 100 != 0) {
return true;
}
else if(year % 400 != 0) {
return false;
}
else {
return true;
}
}
void printBorder(FILE* out)
{
int i = 0;
for(i = 0; i < 80; i++)
fprintf(out,"*");
fprintf(out, "n");
}

4. bool checkInvalidDate(node_t *node) {
int year = (int)node->birthday.year;
if(node->birthday.day < 1 || node->birthday.year < 1) {
return true;
}
if(strcmp(node->birthday.month, "February") == 0) {
if(isLeapYear(year)) {
if(node->birthday.day > 29) {
return true;
}
}
else if(node->birthday.day > 28) {
return true;
}
}
else if((strcmp(node->birthday.month, "April") == 0) || (strcmp(node->birthday.month, "June")
== 0) ||
(strcmp(node->birthday.month, "September") == 0) || (strcmp(node->birthday.month,
"November") == 0)) {
if(node->birthday.day > 30) {
return true;
}
}
else {

5. if(node->birthday.day > 31) {
return true;
}
}
return false;
}
void add(node_t **node, node_t **head) {
node_t* current = *head;
while(current != NULL) {
//comparing first and last names to check for duplicates; if duplicate the info isn't added to the
list
if((strcmp(current->firstName, (*node)->firstName) == 0) && (strcmp(current->lastName,
(*node)->lastName) == 0)) {
return;
}
current = current->next;
}
//adding information as a node to the list
(*node)->next = NULL;
if (*head == NULL) {
*head = *node;
}
else {
node_t* lastNode = *head;

6. while(lastNode->next != NULL) {
lastNode = lastNode->next;
}
lastNode->next = *node;
}
}
node_t* readNodeInfo(FILE* input) {
node_t* node = (node_t*)malloc(sizeof(node_t));
assert(node != NULL);
//scanning information using scansets and putting info in appropriate variables
fscanf(input, "%[^,], %[^,], %[^,], %d, %d, %[^,], %[^n]", node->lastName, node->firstName,
node->birthday.month,
&node->birthday.day, &node->birthday.year, node->major, node->standing);
return node;
}
node_t* createList(FILE* input, node_t** head) {
node_t* node = NULL;
node_t* temp = NULL;
char ch;
//scans through file and calls appropriate functions to read text and add nodes
while(!feof(input)) {
node = readNodeInfo(input);
if(!checkInvalidDate(node)) {
add(&node, head);

7. }
temp = node;
ch = fgetc(input);
}
return *head;
}
//prints the list of information to the output file
void printList(FILE* out, node_t* head) {
node_t* temp = head;
if(head == NULL) {
fprintf(stderr, "List is empty.n");
exit(1);
}
else {
printBorder(out);
fprintf(out, "nList Info:n");
while(temp != NULL) {
fprintf(out, "Name:t%s %sn", temp->firstName, temp->lastName);
fprintf(out, "Date of Birth:t%s %d, %dn", temp->birthday.month, temp->birthday.day, temp-
>birthday.year);
fprintf(out, "Major:t%sn", temp->major);
fprintf(out, "Year:t%snn", temp->standing);
temp = temp->next;
}

8. printBorder(out);
}
}
//uses free() to delete the nodes in the list
void deleteList(node_t** head) {
node_t* temp = *head;
node_t* next = NULL;
while(temp != NULL) {
next = temp->next;
free(temp);
temp = next;
}
*head = NULL;
}
int compare_by_lastname(node_t *a, node_t *b)
{
return strcmp(a->lastName, b->lastName);
}
int compare_by_firstname(node_t *a, node_t *b)
{
return strcmp(a->firstName, b->firstName);
}
void sortList(node_t **head, fun_ptr comp) {

9. bool swapped = true;
node_t *ptr1 = *head;
node_t *ptr2 = NULL;
while(swapped) {
swapped = false;
ptr1 = *head;
while(ptr1->next != ptr2) {
if(comp(ptr1, ptr1->next) > 0) {
swapNode(&ptr1, &(ptr1->next));
swapped = true;
}
ptr1 = ptr1->next;
}
ptr2 = ptr1;
}
}
void swapNode(node_t** a, node_t** b) {
node_t *temp = *a;
*a = *b;
*b = temp;
}
functions.h:
#ifndef FUNCTIONS_H

10. #define FUNCTIONS_H
#include <stdio.h>
#include <stdlib.h>
#include "stdbool.h"
//add birthday struct here
typedef struct birthday {
int day;
int year;
char month[50];
} birthday_t;
//add node_t struct here (this struct will represent a node in the
//linked list)
typedef struct node {
char firstName[50];
char lastName[50];
birthday_t birthday;
char major[50];
char standing[50];
struct node *next;
} node_t;
//implement these:
/*Parameters: node - node of struct node
* head - head node of struct node, beginning of linked list

11. * Return: void
* This function adds a new node to the end of the linked list.
*/
void add(node_t **node, node_t **head);
bool checkInvalidDate(node_t *node);
/*Parameters: input - file pointer pointing to the input file where data is read
* when program is run.
* Return: node_t
* This function reads the information from the provided file and stores it in
* the appropriate variables in a node.
*/
node_t* readNodeInfo(FILE* input);
/*Parameters: input - file pointer pointing to the input file where data is read
* when program is run.
* head - head node of struct node, beginning of linked list
* Return: node_t
* This function calls add() and readNodeInfo() to read in information and then
* add that information to the linked list.
*/
node_t* createList(FILE*, node_t**);
/*Parameters: out - file pointer pointing to the output file where data is written to
* when program is run.
* head - head node of struct node, beginning of linked list

12. * Return: void
* This function prints the list of information to the output file.
*/
void printList(FILE*, node_t*);
/*Parameters: out - file pointer pointing to the output file where data is written to
* when program is run.
* Return: void
* This function prints the border of asterik's included as part of the output.
*/
void printBorder(FILE*);
/*Parameters: head - head node of struct node, beginning of linked list
* Return: void
* This function uses free() to delete the nodes in the linked list.
*/
void deleteList(node_t**);
typedef int(*fun_ptr)(node_t*, node_t*);
int compare_by_lastname(node_t*, node_t*);
int compare_by_firstname(node_t*, node_t*);
void sortList(node_t**, fun_ptr comp);
bool isLeapYear(int);
void swapNode(node_t** a, node_t** b);
#endif
Here is an example of what the info in the text file the program reads from looks like, for
reference:

13. Kennedy,Leon,September,29,1998,CS/BS,Senior
Again, thank you. I greatly appreciate your help. I'm at a dead end.