file i/o writing and reading file in c - c

Question

I am new in c programming.I just start to learn file i/o.So my problem here is after I enter all the data for write file,my program say there is a problem and exited.Which part of my program is wrong？
//THIS PROGRAM WRITE RECORDS IN A TXT.FILE AND THEN READ AND DISPLAY THE RECORDS IN A TXT.FILE
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
struct student
{
char MatricNo[20];
int matric[20];
char CourseNo[20];
int course[20];
char Grade[20];
float Value[20];
}s[10];
int count=0;
int i,j, no,nu;
int write();
int read(int i, int j);
int main()
{
int choice;
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i",&choice);
while(choice!=3)
{
switch(choice)
{
case 1:
write();
break;
case 2:
read(i, j);
break;
case 3:
return 0;
break;
default:
break;
}
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i",&choice);
}
fflush(stdin);
getchar();
return 0;
}
// for write data to txt file
int write()
{
FILE *fw;
fw=fopen("Register Table.txt","w");
printf("\nEnter number of student :");
scanf("%d",&no);
for(i=0;i<no;i++)
{
printf("\nEnter student MatricNo :");
scanf("%s",&s[i].MatricNo);
printf("\nEnter number of courses :");
scanf("%d",&nu);
for(j=0; j < nu; j++)
{
printf("\nEnter student CourseNo :");
scanf("%s",&s[j].CourseNo);
printf("\nEnter student Grade :");
scanf("%s",&s[j].Grade);
printf("\nEnter student value :");
scanf("%.2f",&s[j].Value);
fflush(stdin);
fprintf(fw,"%5s %5s %5s %.2f\n",s[i].MatricNo,s[j].CourseNo,s[j].Grade,s[j].Value);
fclose(fw);
}
}
}
int read(int i, int j)
{
FILE *fr;
//read data from txt file
fr=fopen("Register Table.txt","r");
if(!fr){
printf("not file");
return 0;
}
else
return 1;
printf("\n\n\t **Register Table **\n");
while(fscanf(fr,"%5s %5s %5s %.2f",&s[i].MatricNo,&s[j].CourseNo,&s[j].Grade,&s[j].Value)==1)
{
//display data from txt file
printf("\n\n MatricNo\t CourseNo\t Grade\t\t Value");
for(i=0;i<no;i++)
{
for(j=0; j < nu; j++)
{
printf("\n\n %5s %5s %5s %.2f",s[i].MatricNo,s[j].CourseNo,s[j].Grade,s[j].Value);
}
}
printf("\n\n");
}
fclose(fr);
}
ok,i edited my program and this is it.But now the problem is after i write the file,it could not be read.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
struct student
{
char MatricNo[20];
int matric[20];
char CourseNo[20];
int course[20];
char Grade[20];
float Value[20];
}s[10];
int count=0;
int i,j, no,nu;
int write();
int read(int no, int nu);
FILE *fw;
int main()
{
int choice;
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i",&choice);
while(choice!=3)
{
switch(choice)
{
case 1:
write();
break;
case 2:
read(no, nu);
break;
case 3:
return 0;
break;
default:
break;
}
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i", &choice);
}
fflush(stdin);
getchar();
return 0;
}
// for write data to txt file
int write()
{
fw=fopen("Register Table.txt","w");
printf("\nEnter number of student :");
scanf("%d", &no);
for(i=0;i<no;i++)
{
printf("\nEnter student MatricNo :");
scanf("%s", &s[i].MatricNo);
printf("\nEnter number of course :");
scanf("%d", &nu);
for(j=0; j < nu; j++)
{
printf("\nEnter student CourseNo :");
scanf("%s", &s[i].CourseNo[j]);
printf("\nEnter student Grade :");
scanf("%s", &s[i].Grade[j]);
printf("\nEnter student value :");
scanf("%f", &s[i].Value[j]);
}
}
fprintf(fw,"%s %s %s %.2f\n", s[i].MatricNo, s[i].CourseNo[j], s[i].Grade[j], s[i].Value[j]);
fclose(fw);
}
int read(int no, int nu)
{
FILE *fr;
//read data from txt file
fr=fopen("Register Table.txt","r");
printf("\n\n\t **Register Table **\n");
for(i=0;i<no;i++)
{
for(j=0; j < nu; j++)
{
fscanf(fr,"%s %s %s %.2f", &s[i].MatricNo, &s[i].CourseNo[j], &s[i].Grade[j], &s[i].Value[j]);
}
}
//display data from txt file
printf("\n\n MatricNo\t CourseNo\t Grade\t\t Value");
for(i=0;i<no;i++)
{
for(j=0; j < nu; j++)
{
printf("%s %s %s %.2f", s[i].MatricNo, s[i].CourseNo[j], s[i].Grade[j], s[i].Value[j]);
}
}
printf("\n");
fclose(fr);
}

Answer 1

1-you can not write on file because you close the FILE pointer fw in write() function in for loop.
2-You can not read because you exit read() function either file is valid or invalid with this code.
if(!fr){
printf("not file");
return 0;
}
else
return 1;
3- your read() function can work only if you call it after write(). Because code does not know value of no and nu if you do not call write() firstly.
I think this code works for you
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
struct student
{
char MatricNo[20];
int matric[20];
char CourseNo[20];
int course[20];
char Grade[20];
float Value[20];
}
s[10];
int count=0;
int i,j, no,nu;
int write();
int read(int no, int nu);
FILE *fw;
int main()
{
int choice;
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i",&choice);
while(choice!=3)
{
switch(choice)
{
case 1:
write();
break;
case 2:
read(no, nu);
break;
case 3:
return 0;
break;
default:
break;
}
printf("To record data to txt type <1>\nTo read data from txt type <2>\nTo end the program type <3>\n\n");
printf("Your Choice: ");
scanf("%i", &choice);
}
fflush(stdin);
getchar();
return 0;
}
// for write data to txt file
int write()
{
fw=fopen("Register Table.txt","w");
printf("\nEnter number of student :");
scanf("%d", &no);
for(i=0;i<no;i++)
{
printf("\nEnter student MatricNo :");
scanf("%s", &s[i].MatricNo);
printf("\nEnter number of course :");
scanf("%d", &nu);
for(j=0; j < nu; j++)
{
printf("\nEnter student CourseNo :");
scanf("%s", &s[i].CourseNo[j]);
printf("\nEnter student Grade :");
scanf("%s", &s[i].Grade[j]);
printf("\nEnter student value :");
scanf("%f", &s[i].Value[j]);
fprintf(fw,"%s %s %s %.2f\n", &s[i].MatricNo, &s[i].CourseNo[j], &s[i].Grade[j], &s[i].Value[j]);
}
}
fclose(fw);
}
int read(int no, int nu)
{
FILE *fr;
//read data from txt file
fr=fopen("Register Table.txt","r");
printf("\n\n\t **Register Table **\n");
for(i=0;i<no;i++)
{
for(j=0; j < nu; j++)
{
fscanf(fr,"%s %s %s %.2f", &s[i].MatricNo, &s[i].CourseNo[j], &s[i].Grade[j], &s[i].Value[j]);
}
}
//display data from txt file
printf("\n\n MatricNot CourseNot Gradett Value");
for(i=0;i<no;i++)
{
for(j=0; j < nu; j++)
{
printf("\n%s %s %s %.2f", &s[i].MatricNo, &s[i].CourseNo[j], &s[i].Grade[j], &s[i].Value[j]);
}
}
printf("\n");
fclose(fr);
}