Thread: Storing information in a file

I need to modify my existing program to read its data from a file. Each data line should have the following separated by a space:
Firstname, Lastname, ID number, 3 test scores.
I am not sure how to do this, any examples or clues would be appreciated.




include <stdio.h>
#include <string.h> // a string will be used for name input
void main () {

char firstname [40];
char lastname [40];
char fullname [80];
char grade; // declaration of varibles
int score1, score2, score3,idnum;
float average;

printf("Enter your first name: ");
scanf("%s", firstname);

printf("Enter your last name: ");
scanf("%s", lastname);

printf("Enter the last 4 of your SS #: ");
scanf("%d", &idnum);

printf("Enter first score ");
scanf ("%d",&score1);

printf("Enter second score ");
scanf("%d", &score2);

printf("Enter third score ");
scanf("%d", &score3);

average = (score1 + score2 + score3) / 3.0; //calculates average of scores


if (average <= 60) grade ='F';
if (average >= 60 && average < 70) grade = 'D'; // assigns letter grade to numerical value if (average >= 70 && average < 80) grade = 'C';
if (average >= 70 && average < 80) grade = 'C';
if (average >= 80 && average < 90) grade = 'B';
if (average >= 90 && average < 100) grade = 'A';

strcpy(fullname, lastname);
strcat(fullname,", ");
strcat(fullname, firstname); // string to store name first-last and display last name first


printf("%s \t %d \t %d \t %d \t %d \t %.2f \t %c\n\n",fullname, idnum, score1, score2, score3, average, grade); // output to screen




} //end main

> void main () {
This should be
int main ( ) {

> I need to modify my existing program to read its data from a file.
Do this
FILE *fp = fopen ( "file.txt", "r" );

Then change all your scanf calls like so
scanf("%s", firstname);
to
fscanf( fp, "%s", firstname);


Then you probably need to figure out how to make it loop until the end of file....

I have tried the suggestions you posted. When I run the program I get the error "stream!=NULL." I do not know how to make it loop to the end. Could this be the cause?

> When I run the program I get the error "stream!=NULL."
This probably means that you didn't open the file

You did this
FILE *fp = fopen ( "file.txt", "r" );

But you didn't do this
if ( fp == NULL ) {
// error
}

Before you tried to do this
fscanf( fp, "%s", firstname);

Post your code

Salem,
I tried the things you recommended but I have had no luck. I have a few holes in my understanding of the C language and I am sure it is obvious. Can you see what I am doing wrong?



// Purpose:user inputs firstname, lastname, three test scores then calculate numerical average, assign lettergrade and output lastname, firstname three testscores, and lettergrade

#include <stdio.h>
#include <string.h> // a string will be used for name input
int main () {

char firstname [40];
char lastname [40];
char fullname [80];
char grade; // declaration of varibles
int score1, score2, score3,idnum;
float average;


FILE *fp = fopen("file.txt","r");

if ( fp == NULL ) {



printf("Enter your first name: ");
fscanf(fp, "%s", firstname);

printf("Enter your last name: ");
fscanf(fp, "%s", lastname);

printf("Enter the last 4 of your SS #: ");
fscanf(fp, "%d", &idnum);

printf("Enter first score ");
fscanf (fp, "%d",&score1);

printf("Enter second score ");
fscanf(fp, "%d", &score2);

printf("Enter third score ");
fscanf(fp, "%d", &score3);

average = (score1 + score2 + score3) / 3.0; //calculates average of scores






if (average <= 60) grade ='F';
if (average >= 60 && average < 70) grade = 'D'; // assigns letter grade to numerical value if (average >= 70 && average < 80) grade = 'C';
if (average >= 70 && average < 80) grade = 'C';
if (average >= 80 && average < 90) grade = 'B';
if (average >= 90 && average < 100) grade = 'A';


strcpy(fullname, lastname);
strcat(fullname,", ");
strcat(fullname, firstname); // string to store name first-last and display last name first



printf("%s \t %d \t %d \t %d \t %d \t %.2f \t %c\n\n",fullname, idnum, score1, score2, score3, average, grade); // output to screen


}

}

Try
if ( fp != NULL ) {

> FILE *fp = fopen("file.txt","r");
file.txt was just my example
change the name to be the actual name of the file you're trying to read from

> printf("Enter your first name: ");
Since you're reading from a file, you can remove these prompts.
It will still work with them in, you'll just see a lot of text being printed as the file is read though.