Function Problem

[rhouli67]

Hi im a freshman college student in C programming. We are learning how to use functions. For some reason no one in my Lab can get it to work and im the closest. Here is my code:

/*
Ryan Houlihan
Lab2
The goal of this program is to read in a number between 0 and 100 and
print it out as a letter grade.
*/

#include <stdio.h>

int getScore();                                                         /* Function that converts number score to a letter grade */
char convertGrade(int numScore);                                        /* Function that converts inputed number grade to a letter grade */
void showGrade(int numScore, char letterGrade);                         /* Function that prints out the letter grade */

int main()                                                               /* Calls the other three functions */
{
        getScore();
}
        int getScore()                                                   /* Asks user to input a grade form 0-100 8/
        {
                int numScore;

                printf("Please enter a grade from 0-100:\n ");
                scanf("%d", &numScore);

                return(numScore);
        }

        char convertGrade(int numScore)                                  /* Converts number score to a letter grade */
        {

                int numScore;

                if (numScore >= 0 &&  numScore <= 59)
                        showGrade(numScore,'F');

                        else if (numScore >= 60 && numScore <= 69)
                                showGrade(numScore,'D');

                        else if (numScore >= 70 &&  numScore <= 79)
                                showGrade(numScore,'C');

                        else if (numScore >= 80 && numScore <= 89)
                                showGrade(numScore, 'B');

                        else if (numScore >= 90 &&  numScore <= 100)
                                showGrade(numScore, 'A');

                        else
                                showGrade(numScore, 'Z');

                return(0);
        }

        void showGrade(int numScore, char letterGrade)                            /* Prints out the letter grade */
        {
                if(letterGrade == 'Z')
                        printf("%d is not a vaild number. Please enter a number between 0 and 100\n", numScore);
                else
                        printf("Your grade, %d, is equal to an %c\n", numScore, letterGrade);

        }

It complies fine but it just prints this. :

-1074170612 is not a vaild number. Please enter a number between 0 and 100

Any help is appreciated. I have been trying to figure this out for the past 3 hours with no luck. Ugh.

[tabstop]

The code you posted cannot produce the output you claim, since the only function that gets called is getScore. convertScore and showGrade are not called.

(Also note that "if" requires "==" as opposed to "=".)

[Bladactania]

From what I see I don't understand how it prints anything out... in main you only call getscore(). convertgrade (and therefore showgrade) are never called.

Secondly in showGrade you should have if (letterGrade == 'z'). YOu only have one '='.

[rhouli67]

wolverine:~>a.out
-1078499092 is not a vaild number. Please enter a number between 0 and 100
wolverine:~>a.out
-1080232116 is not a vaild number. Please enter a number between 0 and 100
wolverine:~>a.out
-1077909124 is not a vaild number. Please enter a number between 0 and 100
wolverine:~>a.out
-1076233300 is not a vaild number. Please enter a number between 0 and 100
wolverine:~>a.out
-1080088724 is not a vaild number. Please enter a number between 0 and 100
wolverine:~>a.out
-1079091108 is not a vaild number. Please enter a number between 0 and 100

And yes im confused as well. ><

[Bladactania]

in main you should put

convertScore(getScore());

[Meldreth]

convertGrade redeclares numScore but doesn't initialize it. you shouldn't redeclare it at all because it's passed as a parameter.

[rhouli67]

in main you should put

convertScore(getScore());

Im assuming you mean convertGrade(getScore());

and i did and tried to complie and....:

wolverine:~>gcc gradelab.c
/tmp/ccM4cwjx.o: In function `main':
gradelab.c.text+0x1a): undefined reference to `convertGrade'
collect2: ld returned 1 exit status
wolverine:~>

[rhouli67]

convertGrade redeclares numScore but doesn't initialize it. you shouldn't redeclare it at all because it's passed as a parameter.

I did this with everything else the same:

wolverine:~>gcc gradelab.c
gradelab.c: In function 'getScore':
gradelab.c:30: error: 'numScore' undeclared (first use in this function)
gradelab.c:30: error: (Each undeclared identifier is reported only once
gradelab.c:30: error: for each function it appears in.)

And no i didnt remove int numScore; from getScore() function just from the convertGrad(int numScore) function

[Bladactania]

Yeah, my bad... convertGrade

why does convertGrade return a char? it should be

void convertGrade( yadda yadda)

[rhouli67]

ConvertGrade is returning char letterGrade to be used in the showGrade function.

[Bladactania]

ok... try this...

#include <stdio.h>

int getScore(void);
char convertScore2Grade(int);
void showGrade(char);

int main() {
  int numScore = 0;
  char letterGrade = 'Z';

  numScore = getScore();
  letterGrade = convertScore2Grade(numScore);
  showGrade(LetterGrade);

  return 0;
}

int getGrade() {
  int numScore = 0;

  printf("Enter a number between 0 and 100:");
  scanf("%d", numScore);

  return numScore;
}

char convertScore2Grade(int numScore) {
  char letterGrade = 'Z';

  if (numScore >= 0 &&  numScore <= 59) letterGrade = 'F';
  else if (numScore >= 60 && numScore <= 69) letterGrade = 'D';
  else if (numScore >= 70 &&  numScore <= 79) letterGrade = 'C';
  else if (numScore >= 80 && numScore <= 89) letterGrade = 'B';
  else if (numScore >= 90 &&  numScore <= 100) letterGrade = 'A';

  // No else needed since we set the initial value

  return letterGrade;
}

void showGrade(char letterGrade) {
  if (letterGrade == 'Z')  printf("%d is not a vaild number. Please enter a number between 0 and 100\n", numScore);
  else printf("Your score, %d, is equal to an %c\n", numScore, letterGrade);
}

I haven't compiled that so...

[Bladactania]

my bad... change showGrade to the following

void showGrade(int numScore, char letterGrade) {
  if (letterGrade == 'Z')  printf("%d is not a vaild number. Please enter a number between 0 and 100\n", numScore);
  else printf("Your score, %d, is equal to an %c\n", numScore, letterGrade);
}

you will need to change the function prototype to

void showGrade(int, char);

[ralu.]

Your main function should return a value. Pay more attention when typing:

/* Asks user to input a grade form 0-100 8/

It should be an * instead of the 8.

convertGrade function does not return a char! it return an int... but you can declare it void.

void showGrade(int numScore, char letterGrade) expects a char ("letter") not the ascii number of the letter ('letter').

[Bladactania]

good catch ralu... that would be why he's getting the output he's getting.

[rhouli67]

Changed it around a little cause it wouldnt complie and it still wont:

wolverine:~>gcc gradelab2.c
/tmp/ccIa6DPd.o: In function `main':
gradelab2.c.text+0x1d): undefined reference to `getScore'
collect2: ld returned 1 exit status
wolverine:~>

#include <stdio.h>

int getScore(void);
char convertScore2Grade(int);
void showGrade(char, int);

int main() {
  int numScore = 0;
  char letterGrade = 'Z';

  numScore = getScore();
  letterGrade = convertScore2Grade(numScore);
  showGrade(letterGrade, numScore);

  return 0;
}

int getGrade() {
  int numScore = 0;

  printf("Enter a number between 0 and 100:");
  scanf("%d", numScore);

  return numScore;
}

char convertScore2Grade(int numScore) {
  char letterGrade = 'Z';

  if (numScore >= 0 &&  numScore <= 59) letterGrade = 'F';
  else if (numScore >= 60 && numScore <= 69) letterGrade = 'D';
  else if (numScore >= 70 &&  numScore <= 79) letterGrade = 'C';
  else if (numScore >= 80 && numScore <= 89) letterGrade = 'B';
  else if (numScore >= 90 &&  numScore <= 100) letterGrade = 'A';

  // No else needed since we set the initial value

  return letterGrade;
}

void showGrade(char letterGrade, int numScore) {
  if (letterGrade == 'Z')
         printf("%d is not a vaild number. Please enter a number between 0 and 100\n", numScore);
  else
         printf("Your score, %d, is equal to an %c\n", numScore, letterGrade);
}