Help with a very simple C program....Already written, not working right!

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  1. #1
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    Post Help with a very simple C program....Already written, not working right!

    Hey,

    I have to write a program for class that takes in a last name, first name, and exam score and stores them into seperate arrays. No structs in this however. Then I have to print the high score, low score, and avg score. Thats it. I thought that I had it right but it doesnt work correctly when I run it, even though it compiles fine.

    Heres my program...

    Code:
    #include <stdio.h>
    
    #define CLASS_SIZE 10
    #define NAME_SIZE 20
    
    int getInfo(char[][20], double[], char[][20], int);
    void printResults(char[][20], double[], char[][20], int);
    void doCalcs(double[], int);
    
    int main()
    {
            int count = 0;
            char first[10][20];
            char last[10][20];
            double score[10];
    
            count = getInfo(first, score, last, count);
            doCalcs(score, count);
            printResults(first, score, last, count);
    
            return 0;
    }
    
    
    int getInfo(char first[][20], double score[], char last[][20], int count)
    {
            char again='y';
    
            while(again=='y')
    {
            printf("Please enter the student's first name -- ");
            scanf("%s", first[count]);
            printf("Please enter the student's last name -- ");
            scanf("%s", last[count]);
            printf("Please enter the exam score --  ");
            scanf("%lf", &score[count]);
    
            count++;
    
            printf("Would you like to enter another record? (y/n)");
            //scanf("%c", &again);
            scanf("%s", &again);
    }
            return count;
    }
    
    void doCalcs(double score[], int count)
    {
            int i;
            double high;
            double low = 105;
            double avg;
            double total;
    
            for(i=0; i<count; i++)
            {
            if(score[i] > high)
                    {
                    high = score[i];
     		}
            if(score[i] < low)
                    {
                    low = score[i];
                    }
            }
    
            for(i=0; i<count; i++)
            {
            total = total + score[i];
            }
    
            avg = total/count;
    
            printf("Total number of students = %d\n", count);
            printf("Highest score = %lf\n", high);
            printf("Lowest score = %lf\n", low);
            printf("Average score = %lf\n", avg);
    }
    
    void printResults(char first[][20], double score[], char last[][20], int count)
    {
            int i;
            for(i=0; i<count; i++)
            {
            printf("%s, %s %4.2lf\n", last[i], first[i], score[i]);
            }
    }
    This is what Im getting when I enter some information...

    Please enter the student's first name -- Joe
    Please enter the student's last name -- Smith
    Please enter the exam score -- 30
    Would you like to enter another record? (y/n)y
    Please enter the student's first name -- Bob
    Please enter the student's last name -- White
    Please enter the exam score -- 80
    Would you like to enter another record? (y/n)n
    Total number of students = 2
    Highest score = 0.000000
    Lowest score = 0.000000
    Average score = 37270968922511555218815399770931566435968430750338 28121034433494206368125488490594734490445484833985 42932704708245693379119842581045603106586418751351 90047137854599889866604204928347406994246874588887 4194112758707602325504.000000
    7N, 0.00
    , 0.00
    Segmentation fault


    Any help would be greatly appreciated!!!! Thank you!

  2. #2
    Registered User whiteflags's Avatar
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    Initialize all the variables involved in your calculations, for example

    double high = -105.0;
    double low = 105.0;
    double total = 0.0;
    double avg = 0.0;

    Utherwise you will have an undetermined initial value for these very important numbers.

  3. #3
    CSharpener vart's Avatar
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    scanf("&#37;s", &again);
    you cannot do this

    even if the user pressed only 1 char and enter
    scanf will store 2 chars in the pointer provided - the char pressed and nul-char

    if user enters something longer - even more characters will be stored, while you have only place for 1 char
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  4. #4
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    Thank you so much! It works! I had no idea!

  5. #5
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    For some reason when I put &#37;c in there instead, it wont let me enter a character! Its just like the statement is not even there!

  6. #6
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    I have no idea why my program just worked once when I changed the initializations, and now its not working again after no other changes...weird

  7. #7
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    Am i allowed to say scanf("%c", &again) in that spot? Because like I have it commented out, if I have it just like that, the program does not pause to allow me to enter a char and just keeps running outside the loop and finishes...

  8. #8
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    ya u can use scanf("&#37;c", &again).. but before that u should clear the buffer.. for that u can just type getchar();

  9. #9
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    That works! Thats crazy, why do you have to clear the buffer, and why does getchar() do it for you! Ha off to google....

  10. #10
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    thats because in ur program, inside while loop ur adding a value to the charecter variable. as again is a charecter variable only a charecter gets in to it. but as you press enter after entering a charecter variable even the \n value also will be in the buffer of stdin. so by using getchar() function we are just emptying the buffer.

  11. #11
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    Awesome i got ya! Thank you so much!

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