I have a small doubt on fprintf and fwrite.

[srinivas reddy]

The above code is working fine,first am entering the three students data after am closing my console,again am open my console entered again three students data , if am reading all students data am got just last entered few students data,why this occurs???????
and
is there any possibilities to use fwrite instaed of fprintf to store the data into file.

#include<stdio.h>
 
#include<string.h>
#include<time.h>
struct student
{
    int sno;
    char name[50];
};
struct payment
{
    int previous_amount;
    int present_amount;
    long int total_amount;
};
void main()
{
    struct student d[10];
    struct payment p[10];
    int choice,i = 0;
    int num;
    time_t t;
    time(&t);
    FILE *f1,*f2;
    while(1)
    {
        printf("1.Entering student S.no and Name\n");
        printf("2.Edit student details\n");
        printf("3.Payments\n");
        printf("4.Report particula student\n");
        printf("5.Report of all students\n");
        printf("6.Exit\n");
        printf("Enetr your choice\n");
        scanf("%d",&choice);
        switch(choice)
        {
            case 1:
                    f1 = fopen("sno_name.txt","a");
                    if(f1 == NULL)
                    {
                        printf("Error! opening of sno_name file\n");
                        exit(1);
                    }
                    static int a = 0;
                    //printf("Enter the details of Student %d:\n",a);
                    printf("Enter the details of Student :\n");
                    printf("serial Number :");
                    scanf("%d",&d[a].sno);
                    printf("Name :");
                    scanf("%s",d[a].name);
                    printf("\n");
                    fprintf(f1,"%04d\t\t%20s\n",d[a].sno,d[a].name);
                    a++;
                    fclose(f1);
                    break;
            case 2:
                    f1 = fopen("sno_name.txt","w+");
                    f2 = fopen("payment_info.txt","w+");
                    if(f1 == NULL || f2 == NULL)
                    {
                        printf("Error1 opening of sno_name file in read mode\n");
                        exit(1);
                    }
 
                    int m = 0;
                    printf("Enter the serial number you want to edit name\n");
                    scanf("%d",&num);
                    for(m = 0; d[m].sno == num; m++)
                    {
                            printf("The previous name is: %s\n",d[m].name);
                            printf("Enter the modification for that name:");
                            scanf("%s",d[m].name);
                            printf("the previous amount is: %d\n",p[m].previous_amount);
                            printf("Enter the modification for previous payment:");
                            scanf("%d",&p[m].previous_amount);
                            printf("the present amount is: %d\n",p[m].present_amount);
                            printf("Enter the modification for present amount:");
                            scanf("%d",&p[m].present_amount);
                            p[m].total_amount = p[m].previous_amount + p[m].present_amount;
 
                    }
 
                    for(m = 0; a > m; m++)
                    {
 
                        fprintf(f1,"%04d\t%20s\n",d[m].sno,d[m].name);
                        fprintf(f2,"%04d\t%s\t%06d\t%06d\t%09d\n",d[m].sno,d[m].name,p[m].previous_amount,p[m].present_amount,p[m].total_amount);    
                    }
                    fclose(f1);
                    fclose(f2);
                    break;
            case 3:
                    printf("the value of a is %d\n",a);
                    //printf("you are in case3\n");
                    f2 = fopen("payment_info.txt","a");
                    f1 = fopen("sno_name.txt","r");
                    if(f2 == NULL || f1 == NULL)
                    {
                        printf("Error! opening payment_info file\n");
                        exit(1);
                    }
 
                    int b;
                    int pay_no;
 
                    printf("Enter the serial number for payment\n");
                    scanf("%d",&pay_no);
 
                    for(b = 0; a > b; b++)
                    {
                        if(d[b].sno == pay_no)
                        {
                            printf("the value of b is %d\n",b);
                            time(&t);
                            printf("Enter the payment details of student sno is : %d\n",d[b].sno);
                            printf("enter the previous payment:");
                            scanf("%d",&p[b].previous_amount);
                            printf("enter the present payment:");
                            scanf("%d",&p[b].present_amount);
                            p[b].total_amount = p[b].present_amount + p[b].previous_amount;
                            fprintf(f2,"%04d\t%20s\t%06d\t%06d\t%09d\t%s\n",d[b].sno,d[b].name,p[b].previous_amount,p[b].present_amount,p[b].total_amount,ctime(&t));
                            break;
                        }                                                                                                                                                                                                                                                                          
                    }
                    fclose(f1);
                    fclose(f2);
                    break;
            case 4:
                    f1 = fopen("sno_name.txt","r");
                    f2 = fopen("payment_info.txt","r");
                    if(f1 == NULL)
                    {
                        printf("Error! in case 4 opening f1 read mode\n");
                        exit(1);
                    }
                    if(f2 == NULL)
                    {
                        printf("Error! in case 4 opening f2 read mode\n");
                        exit(1);
                    } 
                    int q;
                    printf("Enter the student serial number for details\n");
                    scanf("%d",&q);
                    printf("The details of student is:\n");
                    for(i = 0; a > i; i++)
                    {
                        if(d[i].sno == q)
                        {
                            printf("Serial number is : %d\n",d[i].sno);
                            printf("Name is          : %s\n",d[i].name);
                            printf("Previous amount  : %d\n",p[i].previous_amount);
                            printf("Present  amount  : %d\n",p[i].present_amount);
                            printf("The total amount : %d\n",p[i].total_amount);
                            break;        
                        }
                    }
                    fclose(f1);
                    fclose(f2);
                    break;
            case 5:
                    f1 = fopen("sno_name.txt","r");
                    f2 = fopen("payment_info.txt","a");
                    if(f1 == NULL)
                    {
                        printf("Error! opening f1 read mode\n");
                        exit(1);
                    }
                    if(f2 == NULL)
                    {
                        printf("Error! opening f2 read mode\n");
                        exit(1);
                    } 
                     int k = 0;
                printf("the details of student is:\n");
                    for(k = 0; a > k;k++)
                        {
                            printf("The student sno is : %d\n",d[k].sno);
                            printf("The student name is :%s\n",d[k].name);
                            printf("The student previous payment is: %d\n",p[k].previous_amount);
                            printf("The student present payment is: %d\n",p[k].present_amount);
                            printf("The total amount is :%d\n",p[k].total_amount);
                            printf("\n\n\n");
                        }
                    fclose(f1);
                    fclose(f2);
                f2 = fopen("payment_info.txt","a");
                int n = 0,res = 0;
                for(n = 0; a > n;n++)
                res = res + p[n].total_amount;
                printf("The total amount of all students is : %d\n",res);
                    fclose(f1);
                    fclose(f2);
                    break;
            case 6:
                    exit(1);
            default :
                    printf("Invalid choice\n");
        }
 
    }
    return;
}
 
 
 
 

[Clearner321]

To read from a file there should be fscanf. That is missing in your program.

[srinivas reddy]

can any one explain when do we use fwrite and when do we use fprintf while storing the data into file...
thanks in advance