Calculator

This is a discussion on Calculator within the C Programming forums, part of the General Programming Boards category; Hey I started using this site to learn C yesterday, and I got to the chapter on functions and decided ...

  1. #1
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    Calculator

    Hey I started using this site to learn C yesterday, and I got to the chapter on functions and decided to try and make a little program to do simple calculations.
    This is the what I've written so far;
    Code:
    #include <stdio.h>
    
    int calc ( int x, int y );
    
    int main()
    {
      int x;
      char f;
      int y;
    
      printf( "Please input a number: " );
      scanf( "%d", &x );
      printf("Please choose a function(add, subtract, divide, or multiply):");
      scanf("%c", f );
      printf( "Please input a second number: " );
      scanf( "%d", &y );
      if (f == *);
      {
      printf( "The product of your two numbers is %d\n", mult( x, y ) );
      }
      else if (f == +);
      {
      printf( "The product of your two numbers is %d\n", add( x, y ) );
      }
      else if (f == /);
      {
      printf( "The product of your two numbers is %d\n", divide( x, y ) );
      }
      else (f == -);
      {
      printf( "The product of your two numbers is %d\n", subtract( x, y ) );
    }
      getchar();
    }
    
    int mult (int x, int y)
    {
      return x * y;
    }
    int add (int x, int y)
    {
      return x + y;
    }
    int subtract (int x, int y)
    {
      return x - y;
    }
    int divide (int x, int y)
    {
      return x / y;
    }
    However I can't seem to make it work, I get an error on the lines with the if statements saying; "syntax error before ')' token.
    Can anyone help? Thanks

  2. #2
    CSharpener vart's Avatar
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    if (f == *);

    '*' - to specify the literal constant

    and the ; at the end should be removed


    scanf("&#37;c", f );
    this line also has problems
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  3. #3
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    thanks, that worked, but now i have a new problem lol, subtracting works fine, but if i try adding it just subtracts, and if i enter the * or / keys it automatically skips the option of adding a second number.

  4. #4
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    All your char operators, need that same 'char_here', treatment. Just to expand on Vart's good eye, here.

    if(f == '-')

    is not the same thing as

    if(f == -)

    at all.

  5. #5
    and the hat of wrongness Salem's Avatar
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    > scanf("&#37;c", f );
    What is missing here, compared to your other scanf calls?

    Also note that %c does NOT skip white space unlike all the other simple scanf formats.
    So 3+2
    would be different from 3 +2


    Which compiler are you using?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  6. #6
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    should be an else-if and without the terminating semicolon else (f == -);

  7. #7
    Registered User slingerland3g's Avatar
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    For clarity of code, "Self documenting" code I would replace:

    1. variable f to be operator

    2. You can use if statements here, as you have a short conditional list, but a switch/case statement would be preferred.

    3. As mentioned all your "operators" should be wrapped within single quotes.

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