Thread: Help About a simple calculator pls!!

  1. #1
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    Help About a simple calculator pls!!

    hello all!! I really need a little help! My problem is that I am writing a simple calculator which is actually my homework and it must do calculation like 2*4+5 is 13..that is there is no precedence..But I dont know how I can write +5 after first equ( 2*4)..My program just gives 8 as a result..Pls help me!! what ı wrote::
    Code:
        int main(){
        int a,b,sum,c;
        char ch;
        printf("enter your application\n");
        scanf("%d%c%d",&a,&ch,&b);
        while(ch!='!' ){
            if(ch=='+')
            sum=a+b;
            if(ch=='-')
            sum=a-b;
            if(ch=='/')
            sum=a/b; 
            if(ch=='*') 
            sum=a*b;
          
             scanf("%c%d",&ch,&c);  
                 printf("%d",sum);
        anykey();
        return 0;
    }
    Last edited by Salem; 11-14-2007 at 05:10 PM. Reason: Code tags go around, you guessed it, just the CODE!

  2. #2
    and the hat of int overfl Salem's Avatar
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    Read the first int, then everything after that is 'operation' and 'operand' pairs.
    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.

  3. #3
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    Why don't you assign sum = a before the while() loop? Then you can keep a running total each time through the loop:
    Code:
            if(ch=='+')
                sum += b;
            if(ch=='-')
                sum -= b;
            if(ch=='/')
                sum /= b; 
            if(ch=='*') 
                sum *= b;

  4. #4
    Beautiful to C Aia's Avatar
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    Code:
            if(ch=='+')
                sum += b;
            if(ch=='-')
                sum -= b;
            if(ch=='/')
                sum /= b; 
            if(ch=='*') 
                sum *= b;
    Consider this. If you want an addition ( the first if ); the others if are still going to be checked for truthfulness. If else or switch are better alternatives.

  5. #5
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    Are you also considering in your program when the input of the user is not a single digit? what if it isdouble digit or more?

  6. #6
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    Quote Originally Posted by aaron_88 View Post
    hello all!! I really need a little help! My problem is that I am writing a simple calculator which is actually my homework and it must do calculation like 2*4+5 is 13..that is there is no precedence..But I dont know how I can write +5 after first equ( 2*4)..My program just gives 8 as a result..Pls help me!! what ı wrote::
    Code:
        int main(){
        int a,b,sum,c;
        char ch;
        printf("enter your application\n");
        scanf("%d%c%d",&a,&ch,&b);
        while(ch!='!' ){
            if(ch=='+')
               sum=a+b;
            if(ch=='-')
               sum=a-b;
            if(ch=='/')
               sum=a/b; 
            if(ch=='*') 
               sum=a*b;
          
             scanf("%c%d",&ch,&c);  
                 printf("%d",sum);
        } /* maybe here? */
        anykey();
        return 0;
    }
    I've highlighted the curly brace problem (a typo I suspect).
    Your program logic doesn't DO anything if int c is added in. It just prints up the same sum
    it had before.

  7. #7
    C++まいる!Cをこわせ!
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    Consider a switch instead of that if.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

  8. #8
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    I would probably read the entire line in, and just increment through it until you find a +,-,/,* sign then take everything before that as number1. Store the sign. Read to the next sign(to get number2), do your math and store that as number1. Repeat.

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