newbie question on converting numeric grades to letter grades

Can anyone help me. I am working on a program that reads from a text file, then displays the names and grades on the screen. This is working but I need to convert the number grades to letter grades...This is where I need help. '

Does anyone know how to do this???


Jose

my input text file named:grades.txt is below.........

........................
Jones
55
Brown
81
Smith
89
Alazar
93
Forster
63
Joplin
67
Grey
33
@

...................

screen output below....




******************************
NAME GRADE
-----------------------
Jones 55
Brown 81
Smith 89
Alazar 93
Forster 63
Joplin 67
Grey 33
*******************************



...........................

press 'ENTER' key to continue...


............................

and my program code is below.....

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
#define MAXN 10

void main (void)
{

display_grades();
}


void display_grades()
{

char ch;
char lettergrade[MAXN];
FILE *myFile;
//char student[MAXN][MAX];
//int grade[MAXN][MAX];
char student[MAXN][MAX], grade[MAXN][MAX];
int i;
int j;
//set file path
myFile = fopen ("c:\\temp\\grades.txt","r");


//display grades
printf ("\n");
printf ("\n");
printf ("\n");
printf (" ******************************\n");
printf (" NAME GRADE \n");
printf (" ----------------------- \n");
i=0;

fscanf (myFile, "%s", student[0]);
//...until last ending character in file
while (student[i][0] != '@' && i < MAXN -1)
{
fscanf (myFile, "%s", grade[i]);

//convert to letter grade***Not working
if (grade[i] >= 90)
lettergrade[i] = 'A';
else if (grade[i] >= 80)
lettergrade[i] = 'B';
else if (grade[i] >= 70)
lettergrade[i] = 'C';
else if (grade[i] >= 60)
lettergrade[i] = 'D';
else lettergrade[i] = 'F';
//end of conversion
i++;

fscanf (myFile, "%s", student[i]);
}
for (j=0; j<i; j++)

printf (" %s %s \n", student[j], grade[j]);
fclose (myFile);
printf (" *******************************\n");

//add extra lines
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("press 'ENTER' key to continue...\n");
scanf ("%c",&ch);

}

when posting messages on this forum, enclose your code in [code] tags to make it easier to read.

Code:

---

//convert to letter grade***Not working
if (grade[i] >= 90)
lettergrade[i] = 'A';
else if (grade[i] >= 80)

---

It doesn't work because grade is a two dimensional array, you are treating it as a one dimensional array. grade[i] contains MAX grades, not just one. Try looping through all of the grades in grade[i] and getting the average, then return the letter grade of the average.

>void main (void)
main returns an int, nothing else. Be sure to place return 0; at the end of your main function as well.

display_grades needs to be prototyped:

Code:

---

void display_grades();

void main (void)
{
  display_grades();
}

void display_grades()
{

---

In C an empty argument list does not mean the function takes no arguments, if that is what you want then specify it with void:

void display_grades(void)

Code:

---

myFile = fopen ("c:\\temp\\grades.txt","r");

---

Check myFile to see if fopen succeeded. If not then myFile will be NULL.

I would modify the code to show you exactly what I mean, but I'm in a big hurry. Sorry. :(

-Prelude

I tried to modify my code but I still am not having any success, now it is printing this as the screen output....

very frustrated because I know I am a newbie and this will end up being something easy, anyone know what I am still doing wrong??


Jose

******************************
NAME GRADE
-----------------------
Jones 37813440
Brown 37813480
Smith 37813520
Alazar 37813560
Forster 37813600
Joplin 37813640
Grey 37813680
Grade: ▬
*******************************


press 'ENTER' key to continue...

below is code.....
__________________________________________________

/*
************************************************** ***********************
* *
* "Input/Output Program" *
* author: Jose Gonzales *
* key: #c06 *
* ---PROGRAM HISTORY--- *
* creation date: 08/12/02 *
* last modified: 08/13/02 *
* lines: 72 *
* description: The purpose of this program is to read *
* from a text file then convert the *
* numeric grades to letter grades and *
* sort them in alphabetically order. *
* *
************************************************** ***********************
*/


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
#define MAXN 10

void main (void)
{

display_grades();
}


void display_grades(void)
{

char ch;
char lettergrade[MAXN][MAX];
FILE *myFile;
//char student[MAXN][MAX];
//int grade[MAXN][MAX];
char student[MAXN][MAX];
int grade[MAXN][MAX];
int i;
int j;
//set file path
myFile = fopen ("c:\\temp\\grades.txt","r");


//display grades
printf ("\n");
printf ("\n");
printf ("\n");
printf (" ******************************\n");
printf (" NAME GRADE \n");
printf (" ----------------------- \n");
i=0;

fscanf (myFile, "%s", student[0]);
//...until last ending character in file
while (student[i][0] != '@' && i < MAXN -1)
{
fscanf (myFile, "%i", grade[i]);

//convert to letter grade***Not working
if (grade[i] >= 90 && grade[i] <= 100)
{
lettergrade[i][0] = 'A';
printf ("inside \n");
}
else if (grade[i] >= 80)
lettergrade[i][0] = 'B';
else if (grade[i] >= 70)
lettergrade[i][0] = 'C';
else if (grade[i] >= 60)
lettergrade[i][0] = 'D';
else lettergrade[i][0] = 'F';
//end of conversion
i++;

fscanf (myFile, "%s", student[i]);
}
for (j=0; j<i; j++)

printf (" %s %i \n", student[j], grade[j]);
printf ("Grade: %c \n", lettergrade[j]);
fclose (myFile);
printf (" *******************************\n");

//add extra lines
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("press 'ENTER' key to continue...\n");
scanf ("%c",&ch);

}

_________________________________________________

Quote:

---

Originally posted by jgonzales
I tried to modify my code but I still am not having any success, now it is printing this as the screen output....

very frustrated because I know I am a newbie and this will end up being something easy, anyone know what I am still doing wrong??
<snip>

---

Ok, lesson number 1. Try to listen to all of what people tell you.
- Code tags are needed when you post code (see my sig for an example). (As stated by moi).
- Don't use void main. (As stated by Prelude).
- grade[i] : (As stated by Prelude) it doesn't work because grade is a two dimensional array, you are treating it as a one dimensional array.
- myFile = fopen("c:\\temp\\grades.txt", "r");
Check this worked. (As stated by Prelude).

I'm not going to continue listing the things you have changed. Try again, and if you have problem with specific areas, ask a more specific question.

Okay, I'm back. Here is what I meant with that incoherent rant earlier, don't turn in my code if this is homework. Teachers can tell if you used someone else's source. ;)

Code:

---

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

#define NUM_OF_STUDENTS 3
#define NUM_OF_GRADES  6

static void display_grades ( void );
static char get_letter ( int grade );

int main ( void )
{
  display_grades();
  return 0;
}

static void display_grades ( void )
{
  FILE *input;
  char student_name[BUFSIZ];
  int  student,
      grade,
      average;
  /*
  ** Open the file and check that it was successful.
  */
  if ( ( input = fopen ( "input.txt", "r" ) ) == NULL ) {
    perror ( "File open failure" );
    return;
  }
  /*
  ** Process one student for each iteration.
  */
  for ( student = average = 0; student < NUM_OF_STUDENTS; student++ ) {
    /*
    ** Read the student's name. If fscanf fails then the
    ** file is probably not formatted correctly. Report
    ** the error and terminate processing.
    */
    if ( fscanf ( input, "%s", student_name ) != 1 ) {
      fprintf ( stderr, "Invalid file format\n" );
      return;
    }
    /*
    ** Check for the end of file so we don't accidentally
    ** process another line.
    */
    if ( strcmp ( student_name, "@" ) == 0 )
      return;
    /*
    ** Find the average of all grades for a student.
    */
    while ( fscanf ( input, "%d", &grade ) == 1 )
      average += grade;
    average /= NUM_OF_GRADES;

    /*
    ** Calculate the letter grade and print the record.
    */
    printf ( "%s: ", student_name );
    printf ( "%c\n", get_letter ( average ) );
  }
}

static char get_letter ( int grade )
{
  if ( grade >= 90 )      return 'A';
  else if ( grade >= 80 ) return 'B';
  else if ( grade >= 70 ) return 'C';
  else if ( grade >= 60 ) return 'D';
  else                    return 'F';
}

---

A note to the nitpickers: I normally wouldn't use fscanf in this situation, so shush. :p

-Prelude

Use an & in the printf function when you print an integer or a floating point.

printf("%s %d", cArray[i], &iNum[i]);

>Use an & in the printf function when you print an integer or a floating point.
:confused:

-Prelude

Quote:

---

Originally posted by Troll_King
Use an & in the printf function when you print an integer or a floating point.

printf("%s %d", cArray[i], &iNum[i]);

---

printf expects values not addresses.

Quote:

---

Originally posted by jgonzales


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
#define MAXN 10

void main (void)
{

display_grades();
}


void display_grades(void)
{
...
//okay
fscanf (myFile, "%s", student[0]);
//error
fscanf (myFile, "%i", grade[i]);
...

---

Okay use the '&' before grade[i].

fscanf (myFile, "%i", &grade[i]);

And it will work if memory serves.

I did it, praise Jesus!

thanks for everyone that helped. here is my finished working code..

_________________________________________________


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
#define MAXN 10

void display_grades(void);

void main (void)
{
display_grades();
}


void display_grades(void)
{
//open text file, read and display grades
char ch;
char lettergrade[MAXN];
FILE *myFile;
char student[MAXN][MAX];
int grade[MAXN];
//char student[MAXN][MAX], grade[MAXN][MAX];
int i;
int j;

//open file and check for file error
if (( myFile = fopen("c:\\temp\\grades.txt","r")) == NULL)
{
printf ("Error Opening with File.");
scanf ("%c",&ch);
return;
}

//display grades
printf ("\n");
printf ("\n");
printf ("\n");
printf (" ******************************\n");
printf (" NAME GRADE \n");
printf (" ----------------------- \n");
i=0;

fscanf (myFile, "%s", student[0]);
//...until last ending character in file
while (student[i][0] != '@' && i < MAXN -1)
{
fscanf (myFile, "%i", &grade[i]);
//convert number grades to letter grades
if (grade[i] >= 90 && grade[i] <=100)
lettergrade[i] = 'A';
else if (grade[i] >= 80)
lettergrade[i] = 'B';
else if (grade[i] >= 70)
lettergrade[i] = 'C';
else if (grade[i] >= 60)
lettergrade[i] = 'D';
else
lettergrade[i] = 'F';
//end conversion
i++;
fscanf (myFile, "%s", student[i]);
}


for (j=0; j<i; j++)
{
printf (" %s %c \n", student[j], lettergrade[j]);
}
fclose (myFile);
printf ("\n");
printf (" *******************************\n");

//add extra lines
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("\n");
printf ("press 'ENTER' key to continue...\n");
scanf ("%c",&ch);
}



_________________________________________________

For the third time:
void main(void)
(see previous posts)

And use code tags please!

Code:

---

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define MAX 10
#define MAXN 10


void display_grades(void);

int main (void)
  {
    display_grades();
  }


  void display_grades(void)
  {
    //open text file, read and display grades
    char ch;
    char lettergrade[MAXN];
    FILE *myFile;
    char student[MAXN][MAX];
    int grade[MAXN];
    //char student[MAXN][MAX], grade[MAXN][MAX];
    int i;
    int j;

    //open file and check for file error
    if (( myFile = fopen("c:\\temp\\grades.txt","r")) == NULL)
        {
        printf ("Error Opening with File.");
        scanf ("%c",&ch);
        return;
        }

    //display grades
    printf ("\n");
    printf ("\n");
    printf ("\n");
    printf (" ******************************\n");
    printf ("    NAME    GRADE                  \n");
    printf ("  -----------------------  \n");
    i=0;

    fscanf (myFile, "%s", student[0]);
          //...until last ending character in file
          while (student[i][0] != '@' && i < MAXN -1)
                {
                fscanf (myFile, "%i", &grade[i]);
                    //convert number grades to letter grades
                    if (grade[i] >= 90 && grade[i] <=100)
                        lettergrade[i] = 'A';
                    else if (grade[i] >= 80)
                        lettergrade[i] = 'B';
                    else if (grade[i] >= 70)
                        lettergrade[i] = 'C';
                    else if (grade[i] >= 60)
                        lettergrade[i] = 'D';
                    else
                        lettergrade[i] = 'F';
                    //end conversion
                i++;
                        fscanf (myFile, "%s", student[i]);
                }


                for (j=0; j<i; j++)
                    {
                    printf ("    %s      %c \n", student[j], lettergrade[j]);
                    }
                    fclose (myFile);
                    printf ("\n");
                    printf (" *******************************\n");

  //add extra lines
  printf ("\n");
  printf ("\n");
  printf ("\n");
  printf ("\n");
  printf ("\n");
  printf ("press 'ENTER' key to continue...\n");
  scanf ("%c",&ch);
  }

---

Read Preludes advice again:

main returns an int, nothing else. Be sure to place return 0; at the end of your main function as well.