Thread: Help

  1. #1
    Registered User mill1000's Avatar
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    Nov 2001
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    43

    Unhappy Help

    i cant figure out what is wroung help me please!!!!

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

    int main()
    {
    int num1;
    int op;
    int num2;
    printf ("In this calculator * = Multiply, + = Add, - = subtract and / means divied.\n");
    printf ("Enter the first integer:")
    scanf (" %d", &num1);
    printf ("Enter operator:");
    scanf (" %d", &op);
    printf ("Enter the second integer:");
    scanf (" %d", &num2);
    int answer = num1 op num2;
    printf ("%d", answer);
    system("pause");
    return 0;
    }

  2. #2
    Registered User
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    Aug 2001
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    52
    You ask the user to enter an operator "+, -, *, /"

    >>printf ("Enter operator:");
    >>scanf (" %d", &op);

    The value stored in op is the ASCII value 43, 45, 42, or 47 respectively

    Then you use variable op as an integer value

    >>int answer = num1 op num2;

    In C, variable answer must be declared up front, not on the fly as in C++. Then your compiler should expect a ; after num1.

    num1 op num2 is an error.

    The compiler cannot recognize op as an operator, only as an integer.
    Better planning would be for you to run op thru a switch structure.

    Also, you left out 1 or 2 semicolons.

    HTH,

  3. #3
    Registered User mill1000's Avatar
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    ok i changed one thing and i got rid of one error the only eror left is on line 16 the eror is: parse error before `num2'



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

    int main()
    {
    int num1;
    char op;
    int num2;
    printf ("In this calculator * = Multiply, + = Add, - = subtract and / means divied.\n");
    printf ("Enter the first integer:");
    scanf (" %d", &num1);
    printf ("Enter operator:");
    scanf (" %d", &op);
    printf ("Enter the second integer:");
    scanf (" %d", &num2);
    int answer = num1 op num2;
    printf ("%d", answer);
    system("pause");
    return 0;
    }

  4. #4
    Mayor of Awesometown Govtcheez's Avatar
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    MI
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    > int answer = num1 op num2;

    That's because you can't do it like that. C++ has no idea how to deal with a inputted symbol unless you tell it what do with it. Try something like this instead.

    Code:
    int answer;
    
    if(op == '+')
       answer = num1 + num2;
    else if (op == '-')
       answer = num1 - num2;
    etc., etc....

  5. #5
    Unregistered
    Guest
    try changing this:

    scanf (" %d", &op);

    to this:

    scanf("%c", &op);

    then after you have num1, num2, and op, do a switch based on op, or a series of if/else if statements based on value of op. the if/else if has been demonstrated by Govtcheese. The switch syntax could start something like:

    switch(op)
    {
    case '+':
    //etc.

    The problem is the computer has no idea what + as a char variable means. It can only follow instructions that have been hard coded. Therefore you have to create a link between the variable input and the hardcoded protocol. That's what the if/else if or switch is for.

  6. #6
    Registered User mill1000's Avatar
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    Nov 2001
    Posts
    43
    cant figure out how to print results im bad a c++ help please here's the code

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

    int main()
    {
    int num1;
    char op;
    int num2;
    switch (op)
    {
    case '+':
    num1 + num2;
    case '-':
    num1 - num2;
    case '*':
    num1 * num2;
    case '/':
    num1 / num2;
    }
    printf ("In this calculator * = Multiply, + = Add, - = subtract and / means divied.\n");
    printf ("Enter the first integer:");
    scanf (" %d", &num1);
    printf ("Enter operator:");
    scanf (" %d", &op);
    printf ("Enter the second integer:");
    scanf (" %d", &num2);
    system("pause");
    return 0;
    }

  7. #7
    ¡Amo fútbol!
    Join Date
    Dec 2001
    Posts
    2,138
    Put the switch after the user input. Go through the switch and have the expression stored into another variable called result. Then, print out result.

  8. #8
    Registered User mill1000's Avatar
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    Posts
    43
    so would i like do
    int result = switch;
    becuase i totaly clue less

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