scanf problem

This is a discussion on scanf problem within the C Programming forums, part of the General Programming Boards category; Hi, I need to write a program that has the user input a command such as ADD (adds two numbers), ...

  1. #1
    Registered User
    Join Date
    Nov 2005
    Posts
    10

    character string problem

    Hi,
    I need to write a program that has the user input a command such as ADD (adds two numbers), SUB(subtracts two numbers), DIV( divides), MUL(multiplies) and then input the two numbers. The user is asked to input all three things at one time. Here is the code.

    Code:
    #include<stdio.h>
    #include<math.h>
    
    int performance(char[], int, int);
    
    int main()
    {
      int one;
      int two;
      char com[3];
      int FI;
    
      printf("Enter Instruction:");
      scanf(" %3s %d %d", &com, &one, &two);
    
      FI =  performance( com, one, two);
      printf("the answer is %d\n", FI);
      return(0);
    
    }
    
    int performance(char A[], int B, int C)
    {
      int final;
      char ADD;
      char SUB;
      char DIV;
      char MUL;
    
      if(A[3] == ADD)
      {
        printf("%d", final);
      }
      if(A[3] == SUB)
      {
        final = B - C;
      }
      if(A[3] == DIV)
      {
        final = B / C;
      }
      if(A[3] ==  MUL)
      {
        final = B*C;
      }
      return(final);
    }
    I am not getting the right answers. I think it has something to do with my if statements.

    please help.
    thanks
    Last edited by pinkpenguin; 11-28-2005 at 04:00 PM.

  2. #2
    Just Lurking Dave_Sinkula's Avatar
    Join Date
    Oct 2002
    Posts
    5,006
    Use a string (a null-terminated array of chars) rather than a single character. Also, it would be better to use fgets and sscanf than 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.*

  3. #3
    and the hat of wrongness Salem's Avatar
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    > scanf(" %3s %d %d", &com, &one, &two);
    1. 3s needs a char array of 4 elements, so
    char com[4];
    2. You don't need an & with an array, so
    scanf(" %3s %d %d", com, &one, &two);

    > if(A[3] == ADD)
    As well as being outside the array, you don't define ADD either.
    Perhaps you need to include string.h and do
    if( strcmp(A,"ADD") == 0 )

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