terminate 0 - PLEASE HELP

Hello
My input should terminate when the user enters 0, but I am having problems with where to enter this statement. Please Help someone, anyone.
Thanks in advance, I am in class right now trying to get this problem working quick reply is greatly needed and appreciated. Here's my code:

# include <stdio.h>

int main (void) {
/* Variable declarations: */

int idno;
int test1;
int test2;
int final_test,total_number_of_A,total_number_of_B,tot al_number_of_C;
int total_number_of_D,total_number_of_F;
double semester_average;
total_number_of_A=0;
total_number_of_B=0;
total_number_of_C=0;
total_number_of_D=0;
total_number_of_F=0;
double class_average;
class_average=0;
semester_average=0;
int number_of_students;
number_of_students=0;

/* Function body: */

printf ("***> Enter student idno:");
scanf ("%d", & idno);
printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);

while (idno != 0) {
semester_average=0.20*test1+0.30*test2+0.50*final_ test;
printf ("The semester average is %lf\n", semester_average);

if (semester_average >= 90 && semester_average <= 100)
printf ("The letter grade is A\n");
total_number_of_A = total_number_of_A+1;
if (semester_average >= 80 && semester_average <= 89)
printf ("The letter grade is B\n");
total_number_of_B = total_number_of_B+1;
if (semester_average >= 70 && semester_average<= 79)
printf ("The letter grade is C\n");
total_number_of_C = total_number_of_C+1;
if (semester_average >= 60 && semester_average <= 69)
printf ("The letter grade is D\n");
total_number_of_D = total_number_of_D+1;
if (semester_average >= 0 && semester_average <= 59)
printf ("The letter grade is F\n");
total_number_of_F = total_number_of_F+1;
/* end if */
printf ("***> Enter student idno:");
scanf ("%d", & idno);
printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);
} /* end while */
class_average = (4*total_number_of_A + 3*total_number_of_B + 2*total_number_of_C + 1*total_number_of_D)/number_of_students;
printf ("Grade distribution:");
printf ("A total_number_of_A_grades=total_number_of_A_grades+ 1");
printf ("B total_number_of_B_grades=total_number_of_B_grades+ 1");
printf ("C total_number_of_C_grades=total_number_of_C_grades+ 1");
printf ("D total_number_of_D_grades=total_number_of_D_grades+ 1");
printf ("F total_number_of_F_grades=total_number_of_F_grades+ 1");
printf ("Class average: %lf", class_average);

return 0;
} /* end function main */

Just so you know, enclose all your code on this board in the code tags for easier reading. To answer your question, here's the updated code, look for where I put the statement in the while loop. It's just a simple test right after idno is input to see if it's 0. If it is you break from the loop before reading any more values.

Code:

---

# include <stdio.h>

int main (void) {
/* Variable declarations: */

int idno;
int test1;
int test2;
int final_test,total_number_of_A,total_number_of_B,tot
al_number_of_C;
int total_number_of_D,total_number_of_F;
double semester_average;
total_number_of_A=0;
total_number_of_B=0;
total_number_of_C=0;
total_number_of_D=0;
total_number_of_F=0;
double class_average;
class_average=0;
semester_average=0;
int number_of_students;
number_of_students=0;

/* Function body: */

printf ("***> Enter student idno:");
scanf ("%d", & idno);
printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);

while (idno != 0) {
semester_average=0.20*test1+0.30*test2+0.50*final_test;
printf ("The semester average is %lf\n", semester_average);

if (semester_average >= 90 && semester_average <= 100)
printf ("The letter grade is A\n");
total_number_of_A = total_number_of_A+1;
if (semester_average >= 80 && semester_average <= 89)
printf ("The letter grade is B\n");
total_number_of_B = total_number_of_B+1;
if (semester_average >= 70 && semester_average<= 79)
printf ("The letter grade is C\n");
total_number_of_C = total_number_of_C+1;
if (semester_average >= 60 && semester_average <= 69)
printf ("The letter grade is D\n");
total_number_of_D = total_number_of_D+1;
if (semester_average >= 0 && semester_average <= 59)
printf ("The letter grade is F\n");
total_number_of_F = total_number_of_F+1;
/* end if */
printf ("***> Enter student idno:");
scanf ("%d", & idno);

/*This is the change I made*/
if(idno == 0){ break; }
/*End change I made*/

printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);
} /* end while */
class_average = (4*total_number_of_A + 3*total_number_of_B + 2*total_number_of_C + 1*total_number_of_D)/number_of_students;
printf ("Grade distribution:");
printf ("A total_number_of_A_grades=total_number_of_A_grades+
1");
printf ("B total_number_of_B_grades=total_number_of_B_grades+
1");
printf ("C total_number_of_C_grades=total_number_of_C_grades+
1");
printf ("D total_number_of_D_grades=total_number_of_D_grades+
1");
printf ("F total_number_of_F_grades=total_number_of_F_grades+
1");
printf ("Class average: %lf", class_average);

return 0;
} /* end function main */

---

you see, after you give IDNO zero, it goes on, and then you have to give inputs to other scanfs... so you need to bypass the other lines with an if, that will check if idno is zero, and if so, it will skip all the other lines, and the while loop repeats, the while statment will see that idno is zero, and the loop will be over!
here is the "fixed" code:

Code:

---


# include <stdio.h>

int main (void) {
/* Variable declarations: */

int idno=1, test1, test2, final_test, total_number_of_A=0, total_number_of_B=0, total_number_of_C=0, total_number_of_D=0,total_number_of_F=0;
double semester_average=0, class_average=0;
int number_of_students=0;

/* Function body: */

while (idno) {

printf ("***> Enter student idno:");
scanf ("%d", & idno);
 if (idno) { // the same as idno!=0
printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);


semester_average=0.20*test1+0.30*test2+0.50*final_test;
printf ("The semester average is %lf\n", semester_average);

if (semester_average >= 90 && semester_average <= 100)
printf ("The letter grade is A\n");
total_number_of_A = total_number_of_A+1;
if (semester_average >= 80 && semester_average <= 89)
printf ("The letter grade is B\n");
total_number_of_B = total_number_of_B+1;
if (semester_average >= 70 && semester_average<= 79)
printf ("The letter grade is C\n");
total_number_of_C = total_number_of_C+1;
if (semester_average >= 60 && semester_average <= 69)
printf ("The letter grade is D\n");
total_number_of_D = total_number_of_D+1;
if (semester_average >= 0 && semester_average <= 59)
printf ("The letter grade is F\n");
total_number_of_F = total_number_of_F+1;
/* end if */
 } // the end of the if (idno)
} /* end while */
class_average = (4*total_number_of_A + 3*total_number_of_B + 2*total_number_of_C + 1*total_number_of_D)/number_of_students;
printf ("Grade distribution:");
printf ("A total_number_of_A_grades=total_number_of_A_grades+1");
printf ("B total_number_of_B_grades=total_number_of_B_grades+
1");
printf ("C total_number_of_C_grades=total_number_of_C_grades+
1");
printf ("D total_number_of_D_grades=total_number_of_D_grades+
1");
printf ("F total_number_of_F_grades=total_number_of_F_grades+
1");
printf ("Class average: %lf", class_average);

return 0;
} /* end function main */

---

hi guys
I tried both codes an they both returned errors. Maybe it's my compiler, will you please run the code if you can and let me know if it's my compiler. thanks

You had a bunch of errors in there, 19 to be exact from the start. So I cleaned up the code a bit and fixed the errors, as well as added some much needed formatting ;)

Look at what you had before and what I've done and see if you can find the differences and why I put them there. Take note that I didn't check to see if the program works as planned, that's your job. I just made sure that it compiles.

Code:

---

# include <stdio.h> 

int main(void){
        /* Variable declarations: */
        int idno, test1, test2, final_test,total_number_of_A = 0,total_number_of_B = 0,
            total_number_of_C = 0, total_number_of_D = 0, total_number_of_F = 0;
        double semester_average = 0.0, class_average = 0.0;
        int number_of_students = 0;

        /* Function body: */
        printf ("***> Enter student idno:");
        scanf ("%d", & idno);
        printf ("***> Enter test1:");
        scanf ("%d", & test1);
        printf ("***> Enter test2:");
        scanf ("%d", & test2);
        printf ("***> Enter final_test:");
        scanf ("%d", & final_test);

        while (idno != 0) {
                semester_average=0.20*test1+0.30*test2+0.50*final_test;
                printf ("The semester average is %lf\n", semester_average);

                if (semester_average >= 90 && semester_average <= 100){
                        printf ("The letter grade is A\n");
                        total_number_of_A = total_number_of_A+1;
                }
                if (semester_average >= 80 && semester_average <= 89){
                        printf ("The letter grade is B\n");
                        total_number_of_B = total_number_of_B+1;
                }
                if (semester_average >= 70 && semester_average<= 79){
                        printf ("The letter grade is C\n");
                        total_number_of_C = total_number_of_C+1;
                }
                if (semester_average >= 60 && semester_average <= 69){
                        printf ("The letter grade is D\n");
                        total_number_of_D = total_number_of_D+1;
                }
                if (semester_average >= 0 && semester_average <= 59){
                        printf ("The letter grade is F\n");
                        total_number_of_F = total_number_of_F+1;
                }/* end if */

                printf ("***> Enter student idno:");
                scanf ("%d", & idno);
                if(idno == 0){ break; }

                printf ("***> Enter test1:");
                scanf ("%d", & test1);
                printf ("***> Enter test2:");
                scanf ("%d", & test2);
                printf ("***> Enter final_test:");
                scanf ("%d", & final_test);
        } /* end while */

        /*Calculate Class Average*/
        class_average = ((4 * total_number_of_A) + (3 * total_number_of_B) +
                                        (2 * total_number_of_C) + (1 * total_number_of_D))/
                                        number_of_students;

        printf("Grade distribution:");
        total_number_of_A = total_number_of_A + 1; printf("%d", total_number_of_A);
        total_number_of_B = total_number_of_B + 1; printf("%d", total_number_of_B);
        total_number_of_C = total_number_of_C + 1; printf("%d", total_number_of_C);
        total_number_of_D = total_number_of_D + 1; printf("%d", total_number_of_D);
        total_number_of_F = total_number_of_F + 1; printf("%d", total_number_of_F);
        printf("Class average: %lf", class_average);

        return 0;
} /* end function main */

---

Cute Pointer, but I compiled it before I posted and it ran, really without errors it just would not end after I entered 0 and therefore, it didnot display the grade distribution, but the program ran with no errors.

It also ran with no errors after I used your code, however, after I entered 0 it returned a divide error I'm not stating exactly what it gave me though.

Again, thanks for your help and I am going to compare the code and work with it, I do understand what you are tell me and thanks for that, both replies.

I compiled my program again and it ran without errors still, however, it does not terminate when I enter 0, instead it asks for the student idno.

With the code from you, it ran, but after I entered 0 it said divide error and highlighted the class_average line.

I will be up all night working on this error code, thanks for your help!

Okay, I see what you mean by a division by 0. What was causing this was the initialization of number_of_students to 0. Also, you never changed this in your code so it stayed at 0 and the final calculation for the class was based on this. Since you can't divide by 0 you got the error. What I did was change the initialization to 1 since you will always enter at least one student record or immediately exit.

Then after everything else in the loop I added an increment for the number_of_students. That cleared the error though once again I'm not sure exactly what you want this program to do so I'll leave the tweaking to you. :)

About not getting errors before posting, often I've found that when I write something in a different compiler then bring it home to mine and try to compile I get mounds of errors. I don't know why this is, but that could be the reason I got errors and you didn't.

Code:

---

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

int main(void){
        /* Variable declarations: */
        int idno, test1, test2, final_test,total_number_of_A = 0,total_number_of_B = 0,
            total_number_of_C = 0, total_number_of_D = 0, total_number_of_F = 0;
        double semester_average = 0.0, class_average = 0.0;
        int number_of_students = 1;

        /* Function body: */
        printf ("***> Enter student idno:");
        scanf ("%d", & idno);
        if(idno == 0) { exit(0); }
        printf ("***> Enter test1:");
        scanf ("%d", & test1);
        printf ("***> Enter test2:");
        scanf ("%d", & test2);
        printf ("***> Enter final_test:");
        scanf ("%d", & final_test);

        while (idno != 0) {
                semester_average=0.20*test1+0.30*test2+0.50*final_test;
                printf ("The semester average is %lf\n", semester_average);

                if (semester_average >= 90 && semester_average <= 100){
                        printf ("The letter grade is A\n");
                        total_number_of_A = total_number_of_A+1;
                }
                if (semester_average >= 80 && semester_average <= 89){
                        printf ("The letter grade is B\n");
                        total_number_of_B = total_number_of_B+1;
                }
                if (semester_average >= 70 && semester_average<= 79){
                        printf ("The letter grade is C\n");
                        total_number_of_C = total_number_of_C+1;
                }
                if (semester_average >= 60 && semester_average <= 69){
                        printf ("The letter grade is D\n");
                        total_number_of_D = total_number_of_D+1;
                }
                if (semester_average >= 0 && semester_average <= 59){
                        printf ("The letter grade is F\n");
                        total_number_of_F = total_number_of_F+1;
                }/* end if */

                printf ("***> Enter student idno:");
                scanf ("%d", & idno);
                if(idno == 0){ break; }

                printf ("***> Enter test1:");
                scanf ("%d", & test1);
                printf ("***> Enter test2:");
                scanf ("%d", & test2);
                printf ("***> Enter final_test:");
                scanf ("%d", & final_test);

                number_of_students++;
        } /* end while */

        /*Calculate Class Average*/
        class_average = ((4 * total_number_of_A) + (3 * total_number_of_B) +
                                        (2 * total_number_of_C) + (1 * total_number_of_D))/
                                        number_of_students;

        printf("Grade distribution:");
        total_number_of_A = total_number_of_A + 1; printf("%d", total_number_of_A);
        total_number_of_B = total_number_of_B + 1; printf("%d", total_number_of_B);
        total_number_of_C = total_number_of_C + 1; printf("%d", total_number_of_C);
        total_number_of_D = total_number_of_D + 1; printf("%d", total_number_of_D);
        total_number_of_F = total_number_of_F + 1; printf("%d", total_number_of_F);
        printf("Class average: %lf", class_average);

        return 0;
} /* end function main */

---

Pointer, sorry about the code, how do I make it easy to read like you posted. Thanks for your help, I edited the code to work.
After the code I am going to post my output, the output is correct, however, I need for the semester grade to look like this 88 and not 88.00000 any suggestions and how do i skip lines so my output can look nice and neat and not all clustered together.
Again, thanks for all your help, I have really learned alot!

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

int main(void){
/* Variable declarations: */
int idno, test1, test2, final_test,total_number_of_A = 0,total_number_of_B = 0,
total_number_of_C = 0, total_number_of_D = 0, total_number_of_F = 0;
float semester_average = 0.0, class_average = 0.0;
int number_of_students = 1;

/* Function body: */
printf ("***> Enter student idno:");
scanf ("%d", & idno);
if(idno == 0) { exit(0); }
printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);

while (idno != 0) {
semester_average=0.20*test1+0.30*test2+0.50*final_ test;
printf ("The semester average is %lf\n", semester_average);

if (semester_average >= 90 && semester_average <= 100){
printf ("The letter grade is A\n");
total_number_of_A = total_number_of_A+1;
}
if (semester_average >= 80 && semester_average <= 89){
printf ("The letter grade is B\n");
total_number_of_B = total_number_of_B+1;
}
if (semester_average >= 70 && semester_average<= 79){
printf ("The letter grade is C\n");
total_number_of_C = total_number_of_C+1;
}
if (semester_average >= 60 && semester_average <= 69){
printf ("The letter grade is D\n");
total_number_of_D = total_number_of_D+1;
}
if (semester_average >= 0 && semester_average <= 59){
printf ("The letter grade is F\n");
total_number_of_F = total_number_of_F+1;
}/* end if */

printf ("***> Enter student idno:");
scanf ("%d", & idno);
if(idno == 0){ break; }

printf ("***> Enter test1:");
scanf ("%d", & test1);
printf ("***> Enter test2:");
scanf ("%d", & test2);
printf ("***> Enter final_test:");
scanf ("%d", & final_test);

number_of_students++;
} /* end while */

/*Calculate Class Average*/
class_average = ((4 * total_number_of_A) + (3 * total_number_of_B) +
(2 * total_number_of_C) + (1 * total_number_of_D))/
number_of_students;

printf ("Grade distribution:\n");
printf (" A %d\n",total_number_of_A);
printf (" B %d\n",total_number_of_B);
printf (" C %d\n",total_number_of_C);
printf (" D %d\n",total_number_of_D);
printf (" F %d\n",total_number_of_F);
printf ("Class average: %lf", class_average);

return 0;
} /* end function main */


HERE IS MY OUTPUT:

***> Enter student idno:1100
***> Enter test1:85
***> Enter test2:95
***> Enter final_test:100
The semester average is 95.500000
The letter grade is A
***> Enter student idno:1200
***> Enter test1:75
***> Enter test2:65
***> Enter final_test:50
The semester average is 59.500000
***> Enter student idno:1300
***> Enter test1:60
***> Enter test2:50
***> Enter final_test:0
The semester average is 27.000000
The letter grade is F
***> Enter student idno:1400
***> Enter test1:100
***> Enter test2:100
***> Enter final_test:100
The semester average is 100.000000
The letter grade is A
***> Enter student idno:1500
***> Enter test1:60
***> Enter test2:80
***> Enter final_test:90
The semester average is 81.000000
The letter grade is B
***> Enter student idno:0
Grade distribution:
A 2
B 1
C 0
D 0
F 1

this should run better

Code:

---

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

int main(void){
/* Variable declarations: */
int idno, test1, test2, final_test,total_number_of_A = 0,total_number_of_B = 0,
total_number_of_C = 0, total_number_of_D = 0, total_number_of_F = 0;
float semester_average = 0.0, class_average = 0.0;
int number_of_students = 0;

/* Function body: */
printf ("***> Enter student idno:");
scanf ("%d", & idno);
while(idno != 0)
{
 number_of_students++;
 printf ("***> Enter test1:");
 scanf ("%d", & test1);
 printf ("***> Enter test2:");
 scanf ("%d", & test2);
 printf ("***> Enter final_test:");
 scanf ("%d", & final_test);

  semester_average=0.20*test1+0.30*test2+0.50*final_test;

        if (semester_average >= 90 && semester_average <= 100)
        {
                printf ("The letter grade is A\n");
                total_number_of_A = total_number_of_A+1;
        }
        else if (semester_average >= 80 )
        {
                printf ("The letter grade is B\n");
                total_number_of_B = total_number_of_B+1;
        }
        else if (semester_average >= 70)
        {
                printf ("The letter grade is C\n");
                total_number_of_C = total_number_of_C+1;
          }
        else if (semester_average >= 60 ){
                printf ("The letter grade is D\n");
                total_number_of_D = total_number_of_D+1;
        }
        else
        {
                printf ("The letter grade is F\n");
                total_number_of_F = total_number_of_F+1;
                }
  printf ("***> Enter student idno:");
  scanf ("%d", & idno);
} /* end while */

/*Calculate Class Average*/
class_average = ((4 * total_number_of_A) + (3 * total_number_of_B) +
(2 * total_number_of_C) + (1 * total_number_of_D))/
number_of_students;

printf ("Grade distribution:\n");
printf (" A %d\n",total_number_of_A);
printf (" B %d\n",total_number_of_B);
printf (" C %d\n",total_number_of_C);
printf (" D %d\n",total_number_of_D);
printf (" F %d\n",total_number_of_F);
printf ("Class average: %lf", class_average);

return 0;
} /* end function main */

---

you will notice how significantly shorter your program is, there other improvements which could make the program more readable.
improvements are the loop control statement is executed after input of the control variable. This means that other variables are read only if a students figures are processed. This also saves on coding.
notice the if statements are more concise. in your original an input which resulted in a average of between say 89 and 90 would not be processed or would cause problems.
also notice your student number has been initialised to zero prior to first iteration. It increases after subsequent iterations giving a truer result.

thanks bigtamscot,

what did you change or add? How do I add a blank line to space my output? After it returns the student letter grade, I want to skip two lines. Also, is there any where on this board that teaches pseudocode and flowcharts?

Thanks, you guys have been a great help, I have really learned from my errors and all of the help I have recieved from this board. Again thanks, now I can really have a Happy Thanksgiving and I hope that everyone else on this board have a Happy Thanksgiving aswell.
KEEP UP THE GOOD WORK!!!

oops!! sorry bigtmascot my bad, i didn't see your explination postes at the bottom. Wow, you are very good and clear i understood that well as so others on this board, like pointer for one again thanks! one day i'll be answering posts and I will feel proud :) SOON!