stdmng.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

// struture for the students data.
struct std
{
    char name[10], lastname[20];
    int id;
    char dep[20];
    char course[10];
};
// pause
void pause()
{
    printf("\nPress Enter to Continue...");
    while (getchar() != '\n') // clear any leftover input
        ;
    getchar(); // wait for key
}
// add student function
void addStudent()
{
    FILE *fp;
    struct std s;
    printf("\n----Add a Student----\n");
    fp = fopen("student.txt", "a");
    if (fp == NULL)
    {
        printf("\nERROR : File can'nt be opened.\n");
    }
    // fprintf(fp, "Roll No., Name, Department, Course\n");
    // student input
    printf("\nEnter Roll no. : ");
    scanf("%d", &s.id); // the getchar is only needed after scanf function because,See the infoabout.txt.

    printf("\nEnter Firstname : ");
    // gets(s.name);
    // scanf("%s", s.name);
    getchar(); // without this the fgets will not be able to take any input due to the new line character.The new line character can here due to pressing of Enter after typing the roll no., that's why i used the getchar() function to eat up that \n character.
    fgets(s.name, sizeof(s.name), stdin);
    s.name[strcspn(s.name, "\n")] = '\0'; // to remove the newline character generated by the fgets function.

    printf("\nEnter Lastname : ");
    fgets(s.lastname, sizeof(s.lastname), stdin);
    s.lastname[strcspn(s.lastname, "\n")] = '\0';

    printf("\nDepartment : ");
    // getchar();No need. check the infoabout.txt,about the fgets() fucntion work.
    fgets(s.dep, sizeof(s.dep), stdin);
    s.dep[strcspn(s.dep, "\n")] = '\0';

    printf("\nCourse : ");
    // getchar();
    fgets(s.course, sizeof(s.course), stdin);
    s.course[strcspn(s.course, "\n")] = '\0';

    // write to File
    fprintf(fp, "%d %s %s %s %s\n", s.id, s.name, s.lastname, s.dep, s.course);
    fclose(fp);
    printf("\nStudent Added Successfully.");
    pause();
}

// View all students
void viewallstd()
{
    printf("\n----All Students----\n");
    FILE *fp = fopen("student.txt", "r");
    char str[200];
    // char str[sizeof("student.txt")];
    // fgets(str, sizeof("student.txt"), fp); Wrong, size of "student.txt" only takes the size 12 length of the string(stduent.txt)not the file content.MEans it can only take upto 12 character long string.
    if (fp == NULL)
    {
        printf("\nERROR : Cann't open the file.");
    }

    /*fgets(str, sizeof(str), fp); // here fgets is run once and hence the first line of the file gets called.if i run another fgets command the second line should be printed.
    printf("%s", str);*/

    // fgets(str, sizeof(str), fp);
    // printf("%s", str); This prints the next line so. we have to loop it up untill the file ends i.e EOF(End Of File).

    while (fgets(str, sizeof(str), fp) != NULL)
    {
        printf("%s", str);
    }
    fclose(fp);
    pause();
}

// Search a student
void searchstd()
{
    printf("\n----Search a Student----\n");
    struct std s;
    int n;
    char line[40];
    int found = 0;

    printf("Enter Roll no. : ");
    scanf("%d", &n);

    FILE *fp = fopen("student.txt", "r");
    if (fp == NULL)
    {
        printf("\nERROR : File not Found");
        return;
    }

    while (fgets(line, sizeof(line), fp) != NULL)
    {
        // printf("\nRaw line: %s\n", line); // this will show what exactly is being read
        //  check for parsing : debug
        // printf("\nParsed Roll: %d | Name: %s %s | Dept: %s | Course: %s\n", roll, name, lastname, dep, course);
        int parsed = sscanf(line, "%d %s %s %s %s", &s.id, s.name, s.lastname, s.dep, s.course);
        if (parsed == 5)
        {
            // to see the scaned/parsed line
            // printf("\nParsed Roll: %d | Name: %s %s | Dept: %s | Course: %s\n", roll, name, lastname, dep, course);
            if (s.id == n)
            {
                printf("\nStudent Found!");
                printf("\nRoll No. : %d\nName : %s %s\nDepartment : %s\nCourse : %s", s.id, s.name, s.lastname, s.dep, s.course);
                found = 1;
            }
        }
    }
    if (!found)
    {
        printf("\nStudent Not Found ! with Roll No. %d", n);
    }
    fclose(fp);
    pause();
}

// Update data
void updatestd()
{
    struct std s;
    printf("\n----Edit or Update Student data----\n");
    FILE *fp1 = fopen("student.txt", "r");
    FILE *fp2 = fopen("temp.txt", "w");
    int n, m = 0;
    char line[100];
    printf("\nEnter Roll no. : ");
    scanf("%d", &n);
    while (fgets(line, sizeof(line), fp1) != NULL)
    {
        int parsed = sscanf(line, "%d %s %s %s %s", &s.id, s.name, s.lastname, s.dep, s.course);
        if (parsed == 5)
        {
            if (s.id == n)
            {
                // Enter Updated Details
                printf("\nEnter new Name : ");
                scanf("%s", s.name);

                printf("\nEnter new LastName : ");
                scanf("%s", s.lastname);

                printf("\nEnter new Department : ");
                scanf("%s", s.dep);

                printf("\nEnter new Course : ");
                scanf("%s", s.course);

                fprintf(fp2, "%d %s %s %s %s\n", s.id, s.name, s.lastname, s.dep, s.course);
                m = 1;
            }
            else
            {
                // this is for the entire input of the file system.
                fputs(line, fp2);
            }
        }
    }
    fclose(fp1);
    fclose(fp2);

    remove("student.txt");
    rename("temp.txt", "student.txt");
    if (m == 1)
    {
        printf("\nStudent record Updated succesfully.");
    }
    else
    {
        printf("\nStudent with Roll no. %d not found.", n);
    }
    pause();
}
// Delete data
void deletestd()
{
    struct std s;
    FILE *fp1 = fopen("student.txt", "r");
    FILE *fp2 = fopen("delete.txt", "w");
    printf("\n----Delete Student data----\n");
    char line[100];
    int n, m = 0;
    printf("Enter Roll no. : ");
    scanf("%d", &n);
    while (fgets(line, sizeof(line), fp1) != NULL)
    {
        int parsed = sscanf(line, "%d %s %s %s %s", &s.id, s.name, s.lastname, s.dep, s.course);
        if (parsed == 5)
        {
            if (s.id == n)
            {
                m = 1;
            }
            else
            {
                // fprintf(fp2, "%d %s %s %s %s\n", s.id, s.name, s.lastname, s.dep, s.course);//safe, cause we can reformat it as we want.
                fputs(line, fp2); // not safe as fprintf but faster and shorter.
            }
        }
    }
    fclose(fp1);
    fclose(fp2);

    remove("student.txt");
    rename("delete.txt", "student.txt");
    if (m == 1)
    {
        printf("\nStudent record Deleted succesfully.");
    }
    else
    {
        printf("\nStudent with Roll no. %d not found.", n);
    }
    pause();
}

int main()
{
    // addStudent();
    // viewallstd();
    // searchstd();
    // updatestd();
    // deletestd();
    int choice;
    do // do while loop is the best suit here the while loop is a bit laggy and controversial. this works perfectly.
    {
        printf("\n----Student Record System----\n");
        printf("1. Add Student\n");
        printf("2. View All Students\n");
        printf("3. Search Student\n");
        printf("4. Update Student's Data\n");
        printf("5. Delete Student's Data\n");
        printf("6. Exit\n");
        printf("Enter Your Choice : ");
        scanf("%d", &choice);

        switch (choice)
        {
        case 1:
            addStudent();
            break;
        case 2:
            viewallstd();
            break;
        case 3:
            searchstd();
            break;
        case 4:
            updatestd();
            break;
        case 5:
            deletestd();
            break;
        case 6:
            printf("Exiting....\n");
            break;
        default:
            printf("\nEnter a Valid choice.");
            break;
        }
    } while (choice != 6);
    return 0;
}