Simple calculation not working, need help

This is a discussion on Simple calculation not working, need help within the C Programming forums, part of the General Programming Boards category; I am trying to get a program to calculate the side of a triangle. I know this is a simple ...

  1. #1
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    Simple calculation not working, need help

    I am trying to get a program to calculate the side of a triangle. I know this is a simple code, im a first year student. So bare with me

    http://rchevys.com/ffxi/underRATEDGames/test.txt

    For some reason, when it gets to the output for the calculation it just puts 0 instead of the value it should be desplaying. what am i doing wrong here?

  2. #2
    and the hat of wrongness Salem's Avatar
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    > printf("C = %d", C);
    Use %f for floats and doubles, not %d
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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    I changed that but the answer is still coming out to "0"

  4. #4
    and the hat of wrongness Salem's Avatar
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    Betcha didn't change all your scanf() calls to use the correct conversion either...
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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    I changed it to :
    (still no good)

    Code:
    #include <stdio.h>
    #include <math.h>
    #include <windows.h>
    
    double A,B,C,calculation;
    int selection;
    
    
    main()
    {
    	printf("Calcute the side of a traingle...a^2 + b^2 = c^2\n");
    	printf("Which sides do you have?\n");
    	printf("(1) a , b\n(2) b , c\n(3) a , c\n");
    	scanf("%d", &selection);
    		if (selection==1)
    		{
    			printf("Please enter the two sides:\n");
    			printf("A: ");
    			scanf("%f", &A);
    			printf("B: ");
    			scanf("%f", &B);
    			calculation = A*A-B*B;
    			C = sqrt(calculation);
    			printf("C = %f", C);
    		}
    		if (selection==2)
    		{
    			printf("Please enter the two sides:\n");
    			printf("B: ");
    			scanf("%f", &B);
    			printf("C: ");
    			scanf("%f", &C);
    			calculation = B*B-C*C;
    			A = sqrt(calculation);
    			printf("A = %f", A);
    		}
    		if (selection==3)
    		{
    			printf("Please enter the two sides:\n");
    			printf("A: ");
    			scanf("%f", &A);
    			printf("C: ");
    			scanf("%f", &C);
    			calculation = C*C-A*A;
    			B = sqrt(calculation);
    			printf("B = %f", B);
    		}
    	Sleep (50000);
    
    	return 0;
    }

  6. #6
    Just Lurking Dave_Sinkula's Avatar
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    >Betcha didn't change all your scanf() calls to use the correct conversion either...
    Code:
    double A,B,C,calculation;
    /* ... */
    scanf("%f", &A);
    Nope. Use "%lf" for double with scanf.
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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    Code:
    printf("A: ");
    scanf("%1f", &A);
    printf("B: ");
    scanf("%1f", &B);
    calculation = A*A-B*B;
    C = sqrt(calculation);
    printf("C = %f", C);
    I tried that with still no luck. Still giving me 0.0000
    I also tried puting printf("C = %1f", C);
    Same result

  8. #8
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    printf("Please enter the two sides:\n");
    printf("A: ");
    scanf("%f", &A);
    printf("B: ");
    scanf("%f", &B);
    calculation = A*A-B*B;
    C = sqrt(calculation);
    printf("C = %f", C);

    maybe its just me but the formula for finding sides on right
    triangles is :
    (Pathagerean Therom.. SP?)
    A*A + B*B = C*C

    (pay close attention to the + )

    EDIT : i was in a rush so i didnt check your other formula's
    on there, but i suggest you check them if there not giving you the
    correct answer

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    Woops, that was normally a +. I accidently copied and pasted over it when i was trying something else. but thats not the problem.

  10. #10
    Just Lurking Dave_Sinkula's Avatar
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    Quote Originally Posted by Summonerur
    Code:
    printf("A: ");
    scanf("%lf", &A); /* 'ell' -- not 'one' */
    printf("B: ");
    scanf("%lf", &B); /* 'ell' -- not 'one' */
    calculation = A*A-B*B;
    C = sqrt(calculation);
    printf("C = %f", C);
    I also tried puting printf("C = %1f", C);
    No need.
    Code:
    printf("C = %f", C);
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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    ahhh That did the trick. One last question.

    How do I get the printf() to output the answer without rounding off?

  12. #12
    Just Lurking Dave_Sinkula's Avatar
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    Quote Originally Posted by Summonerur
    How do I get the printf() to output the answer without rounding off?
    Could you post an expected input and output to demonstrate exactly what you mean? For example,
    Calcute the side of a traingle...a^2 + b^2 = c^2
    Which sides do you have?
    (1) a , b
    (2) b , c
    (3) a , c
    3
    Please enter the two sides:
    A: 3
    C: 4
    B = 2.645751
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

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    yeah, something like that. where the square root will end up as a very large number. It seems to be rounding it off at random places at times.

    http://rchevys.com/ffxi/underRATEDGames/test.txt

    here is my code again, it has been updated a bit.

  14. #14
    ATH0 quzah's Avatar
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    It seems to be rounding it off at random places at times.
    Welcome to the world of floating point numbers.

    Quzah.
    Hope is the first step on the road to disappointment.

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    Quote Originally Posted by quzah
    Welcome to the world of floating point numbers.

    Quzah.
    Wow! Thanks for the help, I know everything I need to know now.



    Do you actually enjoy sitting here bashing on people who are trying to learn things? I have been looking at previous threads to maybe learn some things off of other peoples questions and I noticed all you do is post sarcastic comments that have absolutely no educational value.

    I am sorry if we are not all as smart as you are or fortunate enough to have had or have professors who know what they are teaching. /bow

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