fprintf function in code writes garbage data into .csv file

Question

I'm trying to create a C program which collect's an applicant's information. When a user is prompted to enter their written subjects, the program writes rubbish data into the .csv file when they wrote one. And sometimes does the same when the number of subjects written is two.

I've tried to clear the buffer stream, but it's no use. Strangely, using different compliers like DevC++, Embarcadero DevC and VS Code produces different results.

Edit: I've also noticed the chances of the rubbish values being written into the file are lowered when the grades of the subjects is lower than the number of subjects written.

Attached below is the code. And an image of the output.

// C libraries.
#include <stdio.h>   // Contains function prototypes for the standard input/output library functions, and information used by them.
#include <conio.h>   // Contains function prototypes for the console input/output library functions.
#include <stdlib.h>  // Contains function prototypes for conversions of numbers to text and text to numbers, memory allocation, random numbers and other utility functions.
#include <string.h>  // Contains function prototypes for string-processing functions.
#include <time.h>    // Contains function prototypes and types for manipulating the time and date.
#include <stdbool.h> // Contains macros defining bool, true and false, used for boolean variables.

struct Applicant
{
    int applicationID;
    int dateOfApplication;
    char lastName[21];
    char firstName[21];
    char middleName[21];
    char dateOfBirth[21];
    int age;
    char gender;
    char address[100];
    char phoneNumber[21];
    char emailAddress[51];
    char mobileNumber[21];
    int numSubjectsWritten;
    char csecSubjects[20][100];
    char grades[20];
    char programmeSelection[10];
};

struct Applicant getApplicantData()
{
    struct Applicant applicant;
    int i = 0;
    int numSubjects;

    // Asking for applicant input for various fields.
    printf("| Personal |");
    printf("\nEnter Last Name: ");
    scanf(" %20s", &applicant.lastName);
    fflush(stdin);

    printf("\nEnter First Name: ");
    scanf(" %20s", &applicant.firstName);
    fflush(stdin);

    printf("\nEnter Middle Name (If you don't have a middle name, leave this field blank.): ");
    gets(applicant.middleName);
    fflush(stdin);

    /*
    printf("\nEnter Date of Birth: ");
    scanf(" %s", &applicant.dateOfBirth);
    fflush(stdin);
    
    printf("\nEnter Gender. 'M' for male, 'F' for female, (M|F): ");
    scanf(" %c", &applicant.gender);
    fflush(stdin);

    printf("\n\n| Contact Information |");
    printf("\nEnter Address: ");
    gets(applicant.address);
    fflush(stdin);
    
    printf("\nEnter Phone Number: ");
    gets(applicant.phoneNumber);
    fflush(stdin);
    
    printf("\nEnter Email Address: ");
    gets(applicant.emailAddress);
    fflush(stdin);
    
    printf("\nEnter Mobile Number: ");
    gets(applicant.mobileNumber);
    fflush(stdin);
    */

    printf("\n\n| Education |");
    printf("\nEnter Number of Subjects Written: ");
    scanf("%d", &applicant.numSubjectsWritten);
    fflush(stdin);

    while (i < applicant.numSubjectsWritten)
    {

        printf("\nEnter the subject: ");
        gets(applicant.csecSubjects[i]);
        fflush(stdin);

        printf("\nEnter the grade for that subject: ");
        scanf(" %c", &applicant.grades[i]);
        fflush(stdin);

        i++;
    }

    return applicant;
}

int main(void)
{
    FILE *file = fopen("Data.csv", "a+");
    int i, j;

    if (!file)
    {
        printf("\nError! Can not open data file.\nPlease contact the Program Addmission Manager as soon as possible with the error message.");
        exit(1);
    }

    else
    {
        struct Applicant applicant = getApplicantData();

        //fprintf(file, "%s:%s:%s:%s:%c:%s:%s:%s:%s", applicant.lastName, applicant.firstName, applicant.middleName, applicant.dateOfBirth, applicant.gender, applicant.address, applicant.phoneNumber, applicant.emailAddress, applicant.mobileNumber);

        fprintf(file, "%s:%s:%s:", applicant.lastName, applicant.firstName, applicant.middleName);

        for (i = 0; applicant.csecSubjects[i][0] != '\0'; i++)
        {
            fprintf(file, " %s", applicant.csecSubjects[i]);
            fflush(stdout);
            fflush(stdin);
            fflush(file);

            fprintf(file, " ( %c):", applicant.grades[i]);
            fflush(stdout);
            fflush(stdin);
            fflush(file);
        }
    }

    return 0;
}

Answer 1

First problems I see:

1. Remove the & from all instances where you scanf a string

2. Don't use gets, or mix scanf and fgets

3. Don't fflush(stdin)

Answer 2

Instead of scanf, consider using a custom-made input method with condition checking and anything you need. I will give an example.

#define BUFFER_SIZE 512

void input(char* buffer){ 
  memset(buffer, 0, BUFFER_SIZE); // Initializing the buffer.
  fgets(buffer, BUFFER_SIZE, stdin);

  strtok(buffer,"\n");
}  

How to take input using that?

void main(){
  int username[BUFFER_SIZE];
  input(username);
}  

A way to write a structure to a file is shown below.

 void Structure_Print(Applicant* applicant, FILE* stream, int no_of_applicant){
   if(no_of_applicant==0){
     fprintf(stdout, "No applicant yet.\n");
     return;
   }
       fprintf(stream, "%s:%s:%s:", applicant.lastName, applicant.firstName, applicant.middleName);
for (i = 0; applicant.csecSubjects[i][0] != '\0'; i++)
    {
        fprintf(stream, " %s:", applicant.csecSubjects[i]);
        fprintf(stream, " %c:", applicant.grades[i]);
    }
   return;
 }  

Also, I noticed how you tried to make it readable while saving it in subject(grade) format. I recommend you to not do that. Your .csv file is just for database. Nobody is going to read it. So just store the data by comma or any character separator. It will make it easier to extract data later.