Intro
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One of my university assignments asked us to create a program using `struct` in order to create a simple event scheduler. This program is for a single day only, not multiple days.
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Sample Input / Output
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For a few reasons, I've opted to create a .GIF to display the sample input / output:
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Code
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#include <stdio.h>
#include <string.h>
#include <stdbool.h>
#include <stdlib.h>
#include <ctype.h>
#define _MAX_EVENTS 10 // 10 Events Max
#define _MAX_DESCRIPTION 101 // 100 Character Description Max
typedef struct { // typedef a struct called event
int hour; // Store the hour / HH
int minute; // Store the minute / MM
char description[_MAX_DESCRIPTION]; // Store the event description
} event;
// Print the menu selection
void printMenu() {
puts("+------ SCHEDULER ------+\n"
"| 1. New Event |\n"
"| 2. Delete Event |\n"
"| 3. Display Schedule |\n"
"| 4. Save Schedule |\n"
"| 5. Load Schedule |\n"
"| 6. Exit |\n"
"+-----------------------+\n");
}
// Return true if an event is NULL, false otherwise
bool isNull(const event *e) { return e == NULL; }
// Allocate memory for and initialize an event
event *initEvent() {
event *e = (event*)malloc(sizeof(event));
e->hour = 0;
e->minute = 0;
strcpy(e->description, "");
return e;
}
// Take user input until value is between min and max inclusive, return the input
int inputRange(const int min, const int max) {
int input = 0;
char temp[21];
char *prompt = "| Enter a number between %d and %d: ";
printf(prompt, min, max);
fgets(temp, 21, stdin);
input = atoi(temp);
while (input > max || input < min) { // Data validation
printf(prompt, min, max);
fgets(temp, 21, stdin);
input = atoi(temp);
}
return input;
}
// Setup a new event with user input and return a pointer to the same event
event* newEvent(event *e) {
if (isNull(e)) { // If e is NULL
e = initEvent(); // Initialize it
}
char *seperator = "+--------------------------------+";
printf("\n%s\n| NEW EVENT |\n%s\n\n", seperator, seperator);
puts("+---------- EVENT TIME ----------+");
e->hour = inputRange(0, 23);
e->minute = inputRange(0, 59);
puts(seperator);
puts("\n+--- EVENT DESCRIPTION ---+");
printf("%s", "| Enter a description: ");
fgets(e->description, _MAX_DESCRIPTION, stdin);
puts("+-------------------------+\n");
puts("| Event successfully added.\n");
return e;
}
// Add an event to an event list at a specified index
void addEventAtIndex(event list[], const event e, const int i) {
if (isNull(&e)) { // if our event is NULL, return
return;
}
list[i].hour = e.hour;
list[i].minute = e.minute;
strcpy(list[i].description, e.description);
}
// Insertion sort by swapping struct members
void sort(event list[], const int size) {
for (int i = 1; i < size; i++) {
for (int j = i; j > 0 && (list[j - 1].hour > list[j].hour || (list[j - 1].hour == list[j].hour && list[j - 1].minute > list[j].minute)); j--) {
int hourJ = list[j].hour;
int minuteJ = list[j].minute;
char descriptionJ[_MAX_DESCRIPTION];
strcpy(descriptionJ, list[j].description);
int hourJMinus1 = list[j - 1].hour;
int minuteJMinus1 = list[j - 1].minute;
char descriptionJMinus1[_MAX_DESCRIPTION];
strcpy(descriptionJMinus1, list[j - 1].description);
list[j].hour = hourJMinus1;
list[j].minute = minuteJMinus1;
strcpy(list[j].description, descriptionJMinus1);
list[j - 1].hour = hourJ;
list[j - 1].minute = minuteJ;
strcpy(list[j - 1].description, descriptionJ);
}
}
}
// Add an event to an event list by sorting it into position
void sortInsert(event list[], int *size, event e) {
addEventAtIndex(list, e, *size); // Add event to the end of the list
(*size)++; // Increment size
// Insertion Sort
sort(list, *size);
}
// Display an event in a readable format: [ID] HH:MM - DESCRIPTION
void printEvent(const event e) {
char h1 = { (e.hour / 10) + '0' }; // Extract the first digit and convert to char (if any, else 0)
char h2 = { (e.hour - (e.hour / 10) * 10) + '0' }; // Extract the second digit and convert to char
char m1 = { (e.minute / 10) + '0' };
char m2 = { (e.minute - (e.minute / 10) * 10) + '0' };
printf("%c%c:%c%c - %s", h1, h2, m1, m2, e.description);
}
// Display all events in an event list
void printEventList(const event list[], const int size) {
if (size == 0) {
puts("\n| You have no events scheduled!\n");
return;
}
char *seperator = "+--------------------------------+";
printf("\n%s\n| MY SCHEDULE |\n%s\n\n", seperator, seperator);
for (int i = 0; i < size; i++) {
printf("| [%d] ", i);
printEvent(list[i]);
}
putchar('\n');
}
// Delete an event from an event list
void deleteEvent(event list[], int *size) {
if (*size == 0) { // If list is empty
puts("\n| Event list already empty.\n");
return;
}
char temp[21];
int id;
char *seperator = "\n+--------------------------------+";
printf("%s\n| DELETE EVENT |%s\n\n", seperator, seperator);
for (int i = 0; i < *size; i++) { // Display the event list so the user can see which event to delete
printf("| [%d] ", i);
printEvent(list[i]);
}
printf("%s", "\n| Enter the ID of an event to delete: ");
fgets(temp, 21, stdin);
id = atoi(temp);
if (id > *size - 1) {
printf("\n| No event located at %d\n", id);
return;
}
printf("| Event [%d] deleted successfully.\n\n", id);
// Set hour and minute to some trivially large value for sorting purposes
list[id].hour = 99;
list[id].minute = 99;
strcpy(list[id].description, "");
if (id != (*size - 1)) { // If the event to remove is already last, there's no need to sort it to last
sort(list, *size);
}
(*size)--; // Decrement the size of the list
}
// Replace all spaces in a string with an underscore
char *encode(char *s) {
for (int i = 0; i < strlen(s); i++) {
if (s[i] == ' ') {
s[i] = '_';
}
}
return s;
}
// Replace all underscores in a string with an spaces
char *decode(char *s) {
for (int i = 0; i < strlen(s); i++) {
if (s[i] == '_') {
s[i] = ' ';
}
}
return s;
}
// Save an event list to file
void saveEventList(char *filename, event list[], int size) {
FILE *f = fopen(filename, "w");
if (f == NULL) { // If our file is NULL, return
return;
}
for (int i = 0; i < size; i++) {
fprintf(f, "%d %d %s", list[i].hour, list[i].minute, encode(list[i].description)); // Encode the description (replace spaces with underscores) before saving it into the file
}
printf("\n| %d %s successfully saved into \"%s\".\n\n", size, (size == 1) ? "event" : "events", filename); // Tenary expression to make sure we're grammatically correct
fclose(f);
}
// Load an event list from file
void loadEventList(char *filename, event list[], int *size) {
FILE *f = fopen(filename, "r");
char temp[6 + _MAX_DESCRIPTION]; // ## ## MAX_DESCRIPTION_LENGTH
if (f == NULL) {
printf("\n| File \"%s\" not found.\n\n", filename);
return;
}
*size = 0; // Set size to 0
while (fgets(temp, sizeof(temp), f)) {
char *word = strtok(temp, " "); // Use space as the token delimiter, get the first token (hour)
list[*size].hour = atoi(word); // Store the token into the list
word = strtok(NULL, " "); // Get the second token (minute)
list[*size].minute = atoi(word);
word = strtok(NULL, " "); // Get the third token (description)
strcpy(list[*size].description, decode(word)); // Decode our word before copying it (remove underscores)
(*size)++; // Increment size with each line (event) added
}
printf("\n| %d %s successfully loaded from \"%s\".\n", *size, (*size == 1) ? "event" : "events", filename);
printEventList(list, *size); // Display the event list when finished, show the user what's been loaded
}
int main() {
event list[_MAX_EVENTS];
int index = 0; // Number of elements in list
int selection = 0;
char file[FILENAME_MAX];
char response = 'Y';
char temp[21];
while (selection != 6) {
printMenu(); // Print the menu
printf("%s", "| Please select an option: "); // Prompt for input
fgets(temp, 21, stdin);
selection = atoi(temp); // Convert string input to int
switch (selection) {
case 1: // New Event
if (index + 1 > _MAX_EVENTS) {
printf("| You can only have %d active events at one time!\n\n", index);
break;
}
sortInsert(list, &index, *newEvent(&list[index]));
break;
case 2: // Delete Event
deleteEvent(list, &index);
break;
case 3: // Display Schedule
printEventList(list, index);
break;
case 4: // Save Schedule
if (index == 0) { // No events, don't save anything
puts("| You have no events in your schedule!\n");
}
else {
printf("%s", "| Please enter a \"filename.txt\": ");
fgets(file, FILENAME_MAX, stdin);
strtok(file, "\n"); // Strip newline from filename
saveEventList(file, list, index);
}
break;
case 5: // Load Schedule
if (index > 0) {
printf("%s", "| Are you sure you want to discard your current schedule? (Y/N): ");
response = toupper(getc(stdin));
char c;
while (((c = getchar()) != '\n') && (c != EOF)); // Clear buffer, from getc();
}
if (response == 'Y') {
printf("%s", "| Please enter a \"filename.txt\": ");
fgets(file, FILENAME_MAX, stdin);
strtok(file, "\n"); // Strip newline from filename
loadEventList(file, list, &index);
}
break;
case 6: // Exit Program
puts("\n| Thank you!\n");
break;
default: // Error
puts("\n| Error in selection\n");
break;
}
}
}
Questions / Concerns
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Hopefully I've improved since my last major [code review][3]. I've tried to keep the comments useful, tell me if I'm still being redundant or need to tone that down. There's a few things I have kept in mind while writing this, including [not repeating myself][4] as best as possible. Was the ASCII formatting when printing a good idea? Or should that just be left when showing the menu.
In what ways can I **improve**, what **shouldn't** I be doing, what **should** I be doing?
[1]: https://i.sstatic.net/Nmt4p.png
[2]: https://i.sstatic.net/xTQgH.gif
[3]: https://codereview.stackexchange.com/questions/110509/scoring-and-grading-answers-against-an-answer-key
[4]: https://en.wikipedia.org/wiki/Don%27t_repeat_yourself