I need help with this simple calculation!!!

ok here is the code:

Code:

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#include <iostream>
using namespace std;
int main()
{
    int t1;
    int t2;
    int sum;
    int div;
    int div1;
    int divided;
{
        int t1;
        cout<<" this will add 2 values of test grades you have entered" <<endl;
        cout<<"enter the value of the first test " <<endl;
        cin>> t1;
        cin.ignore();
        cout<<"You enetered " << t1 << endl;
       
        int t2;
        cout<<"enter the value of the second test " <<endl;
        cin>> t2;
        cin.ignore();
        cout<<"you have entered " << t2 << endl;
        // simple cacl by J-C

        int sum;
        cout<<"THIS IS THE SUM " << t1 + t2 << endl;
       
        int div;
        cout<<"ENter the number you want  to be divided by " <<endl;
        cin>> div;
        cin.ignore();
        cout<<" you have entered " << div << "press enter to see the answer" <<endl;
        }
       
      { int div1;
        div1 = ( sum / div );
        cin.ignore();
        }
       
    { 
    int divided;
        cout<<"the answer is " << divided << endl;
        cin.ignore();
}
      }

---

i just want it to divide SUM ( which is t1+t2 ) by the div1 which is the number the user inputs..... can anyone help me why does it keep saying is 0?

Note that in integer division the fractional portion is truncated, so 1/2 is evaluated to 0.

Quote:

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Originally Posted by J-C

i just want it to divide SUM ( which is t1+t2 ) by the div1

---

In the code you posted, you do not divide by div1, you divide by div and store the result in div1. You then output the value of the uninitialized variable divided. Uninitialized variables may contain any value, which MIGHT happen to be zero, but could also be the phone number of your town comptroller. Get the drift?

The problem noted by laserlight is something you should definitely be aware of, though.

then how about I'm putting in 10 + 10 the sum is = 20 ok that's right but then i put divide by 2 and it says is 0 how so? what do i need to change then?

BTW thanks a lot for the quick reply

Quote:

---

In the code you posted, you do not divide by div1, you divide by div and store the result in div1. You then output the value of the uninitialized variable divided. Uninitialized variables may contain any value, which MIGHT happen to be zero, but could also be the phone number of your town comptroller. Get the drift?

The problem noted by laserlight is something you should definitely be aware of, though.

---

thanks for the reply and yes my bad i mean divide by div not div1 since div is the number the user inputs and div1 is supposed to give the result of SUM divided by div, which is not doing

and yes i am aware of what laserlight said as i replied to him before quoting you.

Division is computer is totally different with normal daily calculation with integer.

the problem is simple, you need to have this sentence in your code:

sum = t1+t2;

I think you must forget this sentence.



------------------------------------------------
codeuu,source code

You never output the result of the division in that code.

THANKS FOR THE HELP GUYS ;)

i have another issue this one is a little harder:

Code:

---

   
a1:
    // TITTLE
    {
    cout<<" SC J 1.0 (BETA) " <<endl;
    cout<<endl;
    cout<<"( simple calc J )"<<endl;
    cout<< endl;
        }
       
          // Enter the first value
         
          cout<<"First Number: ";
          cin>> a1;
          cout<<endl;
          cout<<"Press: + to add, - to subtract, * to multiply and / to divide and press enter ";
          cin >> a;
          cout<<endl;
         
         
         
         
          //if user inputs + then add
         
          if ( a == '+' ) {cout<<"Number to ADD to " << a1 <<" : "; }
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" + "<< b1 <<" = " << a1 + b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }
         
         
          // if user inputs - then substract
         
          if ( a == '-' ) { cout<<" Number to subtract from: " << a1 <<": "; }
          cin>> b1;
          cout<<endl;
          cout<<" Answer: "<< a1 << " - " << b1 <<" = " << a1-b1<<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }
           

          // if user inputs * then multiply
         
          if ( a == '*' ) {
          cout<<" Number to multiply by: "<< a1 <<" : "; }
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" * " << b1 <<" = " << a1*b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }
         
         
         
       
       
          // if user inputs / then divide
               
          if ( a == '/' ) {
              cout<<" Nmber to divide " << a1 <<" by " <<" : ";
              cin>> a1;
              cout<<endl;
              cout<<" Answer " << a1 <<" / " << b1 << " = " << a1 / b1 <<endl; }
              cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }

---

btw is a calculator ...... pretty obvious

you don't have to read all code, it works and everything but i want it to do 2 things:

first : i want to make

Code:

---

if ( a != )

---

so that if you choose any character but

Code:

---

'+', '-', '*', '/';

---

it will return you to label a1:
i tried this

Code:

---

if (a != '+', '-', '*', '/' )
goto a1;

---

isn't this supposed to work? cause it is not.......

SECOND: the adding and subtracting work like a charm, but then the multiplying and dividing don't work at all if i press * does not do what it is supposed to here it is

Code:

---

          // if user inputs * then multiply
         
          if ( a == '*' ) {
          cout<<" Number to multiply by: "<< a1 <<" : "; }
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" * " << b1 <<" = " << a1*b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }
         
         
         
       
       
          // if user inputs / then divide
               
          if ( a == '/' ) {
              cout<<" Nmber to divide " << a1 <<" by " <<" : ";
              cin>> a1;
              cout<<endl;
              cout<<" Answer " << a1 <<" / " << b1 << " = " << a1 / b1 <<endl; }
              cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }

---

so why isn't working while this one is:

Code:

---

if ( a == '+' ) {cout<<"Number to ADD to " << a1 <<" : "; }
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" + "<< b1 <<" = " << a1 + b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          { goto a1; }

---

Don't use gotos. Never, ever, *ever* use gotos. (Unless you can demonstrate decisively that they simplify program logic over the alternatives. Which you almost never can really do.)

The correct way to write this would be:

Code:

---

do {
    {
          cout<<" SC J 1.0 (BETA) " <<endl;
          cout<<endl;
          cout<<"( simple calc J )"<<endl;
          cout<< endl;
    }
       
    // Enter the first value
         
    cout<<"First Number: ";
    cin>> a1;
    cout<<endl;
    cout<<"Press: + to add, - to subtract, * to multiply and / to divide and press enter ";
    cin >> a;
    cout<<endl;
          //if user inputs + then add
         
    if ( a == '+' )
    {
          stuff here
    }
    else if ( a == '-' )
    {
          //stuff here
    }
    else if ( a == '*' )
    {
          // stuff here
    }
    else if ( a == '/' )
    {
          // stuff here     
    }
} while (1); // or whatever condition you want to terminate the loop, maybe a particular character.

---

Code:

---

if (a != '+', '-', '*', '/' )

---

This is incorrect use of the comma operator. It does not do what you think it does. In general the correct way to write this (unnecessary in the above example, BTW) would be:

Code:

---

if (a != '+' && a != '-' && a != '*' && a != '/')

---

Although, in the particular case where you're trying to match one of several chars you could instead just write

Code:

---

if (strchr("+-*/",a) == NULL)

---

:P :P :P :P
LOL i have heard and actually found out for my self that goto is something to be avoided AT ALL times, well it just got proved xD thanks so much man

oh and it does make more sense to use && ..... i just didn't think about it then thanks again so much man you are THE BEST :D

EDIT: ok a little bit of blindness here, i really think i'm going blind...

Code:

---

        while (a != something)
        {
          cout<<" YOU PRESSED A WRONG SYMBOL THAT IS NOT IN SC J 1.0 (BETA) "<<endl;
          cout<<endl;
          cout<<endl;
          system("PAUSE");
          }

---

i really i'm blind cause i can't see what makes it not show the message.....

if i put the semicolon after ) then ok it loops but before it loops i want it to show the message.

Can't say without more context. In isolation, that looks fine. Well, except for being an infinite loop.

thanks for helping Lindley i really appreciate

Code:

---

do
    {  // begins do while loop
    // TITTLE
    {
    cout<<" SC J 1.0 (BETA) " <<endl;
    cout<<endl;
    cout<<"( simple calc J )"<<endl;
    cout<< endl;
    } 

 
          if ( a == '+' )
          {
          cout<<"Number to ADD to " << a1 <<" : ";
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" + "<< b1 <<" = " << a1 + b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          }

} //end of do while loop
       
        while (a != something)
        {
          cout<<" YOU PRESS A WRONG SYMBOL THAT IS NOT IN SC J 1.0 (BETA) "<<endl;
          cout<<endl;
          cout<<endl;
          system("PAUSE");
          }

---

that's not the whole code but i think that sums it up if you want to see the full code just tell me

Code:

---

do
    {  // begins do while loop
    // TITTLE
    {
    cout<<" SC J 1.0 (BETA) " <<endl;
    cout<<endl;
    cout<<"( simple calc J )"<<endl;
    cout<< endl;
    } 

 
          if ( a == '+' )
          {
          cout<<"Number to ADD to " << a1 <<" : ";
          cin>> b1;
          cout<<endl;
          cout<<" Answer " << a1 <<" + "<< b1 <<" = " << a1 + b1 <<endl;
          cout<<endl;
          system("pause");
          cout<<endl;
          cout<<endl;
          }
          else if (...)
          else if (...)
          else if (a != 'q')
          {
                cout<<" YOU PRESS A WRONG SYMBOL THAT IS NOT IN SC J 1.0 (BETA) "<<endl;
                cout<<endl;
                cout<<endl;
                system("PAUSE");
          }
} while (a != 'q'); // 'q' for quit

---

I think that's what you meant.

LOL that is totally what i meant and that works just fine... i just thought that

Code:

---

while (a!=something)
{
//code to execute here
}

---

could still display a message...guess not?

an i have another question

what is the simplest way to say if a cin>> does not equal a number

like if the input is anything but a number to show a message i want

Quote:

---

Originally Posted by J-C

LOL that is totally what i meant and that works just fine... i just thought that

Code:

---

while (a!=something)
{
//code to execute here
}

---

could still display a message...guess not?

---

It can; just don't get confused between the while which *opens* a while loop and the while which *closes* a do/while loop. The latter can't have a block after it.

Quote:

---

Originally Posted by Lindley

It can; just don't get confused between the while which *opens* a while loop and the while which *closes* a do/while loop. The latter can't have a block after it.

---

oh ok ok i got you didn't know the closing while loop could not show a message that's how you learn though by mistakes thanks alot.

I have another question...this is prob my last one for a while,

how would i go about

Code:

---

if ( a!= A NUMBER )
{
cout<<" you did not enter a number, you cannot input character's that are not numbers " <<endl;

---

so i want to make sure they entered a number could be decimal doesn't matter as long as it is a number but if they eneter for example

Code:

---

@ or T or  "

---

get it?


im not sure it's NAN

Quote:

---

Originally Posted by J-C

so i want to make sure they entered a number could be decimal doesn't matter as long as it is a number but if they eneter for example @ or T or "
get it?
im not sure it's NAN

---

if you're comparing a single character a to see if it is not a digit, you can use the same function Lindlay recommended earlier:

Code:

---

if (strchr("0123456789",b) == NULL)

---

Adding support for decimals makes it slightly harder -- you need to add '.' to the list, and keep track of if you have already seen a decimal point inside this particular number. This can be simply done by using a boolean flag that you set to true the first time you see a decimal, and you reset to false when you're done with that number.

If you just want to convert a character / string to a number without verifying that it is actually a number, you can use atoi()... if they enter something that is not a number, atoi returns 0.

There's also an isdigit() function which operates on individual characters.