C Programming Read and Write using Array - c

Question

I have a program in which I am supposed to add in two functions that will read elements from an array and write them to a file, and to read from a file and put the information into the array.
Questions:
saveFile(char *fileName); The saveFile function will read each element in the array (the person directory) and save the data into a disk file.
loadFile(char *fileName); The loadFile function will read each item in the disk file and load it into the array (the person directory). The loadFile must generate exactly the same data structure and same data that the saveFile function reads.
Add necessary code to call the safeFile and loadFile functions in your program, including: Declare a global file name myDatabase; Call the saveFile(myDatabase) before existing the main function to save the data; Call the loadFile(myDatabase) at the beginning of the main function to load the data back into the array of person directory
So far this is what I have come up with:
void saveFile(char *fileName) {
FILE *fPointer;
fPointer = fopen(fileName, "w");
fprintf(fPointer, directory);
fclose(fPointer);
}
void loadFile(char *fileName) {
FILE *fPointer;
fPointer = fopen(fileName, "r");
while (!feof(fPointer)) {
fgets(directory, MAX, fPointer);
puts(directory);
fclose(fPointer);
}
}
I only have a basic understanding of reading and writing files. My program complies fine, but whenever I run it a file that should contain the values in the array is not created. If someone can explain how I could use my above code to properly implement it with the code that is given to me that would be great!
Here is the entire code:
/**
Course: CSE240
Instructor: Dr. Chen
Assignment Name: Homework 4 Solution
Solved by: Garrett Gutierrez 2/7/2015
**/
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#pragma warning(disable: 4996)
#define MAX 100
// Changed: deploma to diploma.
typedef enum { diploma = 0, bachelor, master, doctor } education;
// A struct to hold attributes of a person
struct person {
char name[30];
char email[30];
int phone;
education degree;
};
/******************* Global Variable Section *******************/
struct person directory[MAX]; // an array of structures, 100 entries
int tail = 0; // global variable
/******************* Foward Declaration Section *******************/
void branching(char c);
int delete_person();
void flush();
int insertion();
int print_person(int i);
int print_all();
int search_person();
void shift_data(char* name, char* email, int phone, education educationLevel);
int main()
{
// Print a menu for selection
char ch = 'i';
ungetc('\n', stdin); // Inject the newline character into input buffer
do {
printf("Enter your selection\n");
printf("\ti: insert a new entry\n");
printf("\td: delete an entry\n");
printf("\ts: search an entry\n");
printf("\tp: print all entries\n");
printf("\tq: quit \n");
flush(); // Flush the input buffer. To be discussed later
ch = tolower(getchar()); // Convert any uppercase char to lowercase.
branching(ch);
} while (ch != 113); // 113 is 'q' in ASCII
return 0;
};
// Flush the input buffer. To be discussed later
void flush()
{
int c;
do {
c = getchar();
} while (c != '\n' && c != EOF);
};
// Branch to different tasks: insert a person, search for a person, delete a person
// print all added persons.
void branching(char c)
{
switch (c) {
case 'i':
insertion();
break;
case 's':
search_person();
break;
case 'd':
delete_person();
break;
case 'p':
print_all();
break;
case 'q':
break;
default:
printf("Invalid input\n");
}
};
// Inserts the person lexigraphically. Note: A < a so all capital letters will be ordered first.
int insertion()
{
education educationLevel = 0;
char name[MAX], email[MAX];
int i = 0, phone;
// Case 1: The structure is filled.
if (tail == MAX) {
printf("There are no more places to insert.\n");
return -1;
}
// Case 2: The structure still has unfilled slots.
else
{
printf("Enter the name:\n");
scanf("%s", name);
printf("Enter the phone number:\n");
scanf("%d", &phone, sizeof(directory[tail].phone));
printf("Enter the e-mail:.\n");
scanf("%s", email);
//********** Question 1 ************
do {
printf("Enter the degree: select 0 for diploma, select 1 for bachelor, select 2 for master, or select 3 for doctor:\n");
scanf("%d", &educationLevel);
if (educationLevel < diploma || educationLevel > doctor)
{
printf("Please enter a value from 0 to 3.\n");
}
} while (educationLevel < diploma || educationLevel > doctor);
//**********************************************
//********* Question 2 ************
shift_data(name, email, phone, educationLevel);
//*****************************************
tail++;
printf("The number of entries = %d\n", tail);
}
return 0;
};
// Print the name, e-mail, phone, and education level of one person in the directory
int print_person(int i)
{
printf("\n\nname = %s\n", directory[i].name);
printf("email = %s\n", directory[i].email);
printf("phone = %d\n", directory[i].phone);
//************ Question 1 ******************
switch (directory[i].degree)
{
case diploma:
printf("degree = diploma\n");
break;
case bachelor:
printf("degree = bachelor\n");
break;
case master:
printf("degree = master\n");
break;
case doctor:
printf("degree = doctor\n");
break;
default:
printf("System Error: degree information corruption.\n");
break;
}
//****************************************
return 0;
}
// Print the name, e-mail, phone, and education level of each person in the directory
int print_all()
{
int i;
//Case 1: The structure is empty
if (tail == 0)
{
printf("No entries found.");
}
// Case 2: The structure has at least one item in it
else
{
for (i = 0; i < tail; i++) {
print_person(i);
}
printf("\n");
}
return 0;
};
//********** Question 3 **************
//Find a person by comparing names.
int search_person()
{
char sname[30];
int i = 0;
struct person* iterator = directory;
printf("Please enter the name to be searched for:\n");
scanf("%s", sname); //sname is an array, no & needed
while (i < tail)
{
if (strcmp(sname, iterator->name) == 0)
{
print_person(i);
return i;
}
iterator++;
i++;
}
printf("The name does not exist.\n");
return -1;
};
//***************************************
// Delete a person after finding that person via their name.
int delete_person()
{
int i, k;
k = search_person();
// Case 1: The person is not in the directory
if (k == -1)
{
printf("The name does not exist.\n");
return -1;
}
// Case 2: The person was found in the directory
else {
for (i = k; i<tail; i++)
{
strcpy(directory[i].name, directory[i + 1].name);
directory[i].phone = directory[i + 1].phone;
strcpy(directory[i].email, directory[i + 1].email);
printf("The index deleted is: %d\n", k);
}
tail--;
return k;
}
};
void shift_data(char* name, char* email, int phone, education educationLevel)
{
int i = 0, j = 0;
// Case 1: Empty List
if (tail == 0)
{
strcpy(directory[tail].name, name);
strcpy(directory[tail].email, email);
directory[tail].phone = phone;
directory[tail].degree = educationLevel;
return;
}
while (i < tail)
{
// Case 2: Beginning or middle of list
if (strcmp(name, directory[i].name) < 0)
{
j = tail;
while (j > i)
{
strcpy(directory[j].name, directory[j - 1].name);
strcpy(directory[j].email, directory[j - 1].email);
directory[j].phone = directory[j - 1].phone;
directory[j].degree = directory[j - 1].degree;
j--;
}
strcpy(directory[i].name, name);
strcpy(directory[i].email, email);
directory[i].phone = phone;
directory[i].degree = educationLevel;
return;
}
i++;
}
// Case 3: End of list
strcpy(directory[tail].name, name);
strcpy(directory[tail].email, email);
directory[tail].phone = phone;
directory[tail].degree = educationLevel;
};
void saveFile(char *fileName) {
FILE *fPointer;
fPointer = fopen(fileName, "w");
fprintf(fPointer, directory);
fclose(fPointer);
}
void loadFile(char *fileName) {
FILE *fPointer;
fPointer = fopen(fileName, "r");
while (!feof(fPointer)) {
fgets(directory, MAX, fPointer);
puts(directory);
fclose(fPointer);
}
}

Answer 1

fprintf is not the correct function to be calling to output structures to a file, and you're using it wrongly anyway.
It requires a format string after the file handle which decides how the items in the rest of the call will be formatted.
The function you want is fwrite (and fread to get them back). These read and write the underlying data in full.
For example, to write the entire directory structure array, you would use something like:
size_t written = fwrite (directory, sizeof (directory), 1, fPointer);
if (written != 1) puts ("Something went horribly wrong");
And reading it back is pretty much the same except using fread instead of fwrite.
That's probably the easiest approach but, since it reads and writes the entire array, it's not really the most efficient in terms of space taken on disk. You could do it piecemeal, one record at a time but that introduces code complexity and is probably not really necessary for a 100-element array.
If you opt for storing the entire array regardless, you'll probably want to save away tail as well so you can remember how many items in the array are in use:
size_t written = fwrite (&tail, sizeof (tail), 1, fPointer);
if (written != 1) puts ("Something went horribly wrong");

Answer 2

void loadFile(char *myDatabase)
{
FILE *fileBuffer = fopen(myDatabase, "rb");
if (fileBuffer != NULL)
{
fread(&tail, sizeof(tail), 1, fileBuffer);
for (int i = 0; i < tail; i++)
{
fread(directory[i].name, sizeof(directory[i].name), 1, fileBuffer);
fread(&directory[i].phone, sizeof(&directory[i].phone), 1, fileBuffer);
fread(directory[i].email, sizeof(directory[i].email), 1, fileBuffer);
fread(&directory[i].degree, sizeof(&directory[i].degree), 1, fileBuffer);
}
fclose(fileBuffer);
}
This is what I have for the same code..