Function problem

I am trying to make a function that repeats till I say exit out. For some strange reason it's complaining about the answers.

Code:

Code:

---

int add()
{
        char answer;
        int a,b;
        int total;

        do
        {
                std::cout<<"Enter two numbers: ";
                std::cin>>a,b;

                total = a+b;
                std::cout<< total <<"\n\n";
                std::cout<<"Do you wish to continue: Y/N";
                std::cin>>answer;
        } while (answer = y || answer = Y);

        std::cout<<"Returning to menu\n\n";
        return 0;
}

---

Error:

Code:

---

In file included from index.cpp:2:0:
functions.cpp: In function âint add()â:
functions.cpp:9:11: error: âyâ was not declared in this scope
functions.cpp:20:34: error: âYâ was not declared in this scope

---

90 posts is enough to know about code tags.

Look at this line. What do you see wrong?

while (answer = y || answer = Y);

Quote:

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Originally Posted by GCDEF

90 posts is enough to know about code tags.

Look at this line. What do you see wrong?

while (answer = y || answer = Y);

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Actually, I thought I had them right. However, it's not working. I even googled it up on V board.

Quote:

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Originally Posted by GCDEF

90 posts is enough to know about code tags.

Look at this line. What do you see wrong?

while (answer = y || answer = Y);

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Sorry, I had the "/" in the wrong direction. I actually did use tags.

Quote:

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Originally Posted by GCDEF

Look at this line. What do you see wrong?

while (answer = y || answer = Y);

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I'm not sure honestly. It's been a long time since I've done programming. I've probably made a silly mistake. I've tried several different variants.

Code:

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while (answer == y | answer == Y);

---

Code:

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while ((answer = y) | (answer == Y));

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Code:

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while (answer == "y" | answer == "Y");

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= is assignment
== is the equality operator
y is a variable named y
'y' is a char

now you should be able to fix it

Quote:

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Originally Posted by Russco

= is assignment
== is the equality operator
y is a variable named y
'y' is a char

now you should be able to fix it

---

Thank you sir. I knew it was a simple mistake.

One more:
|| is a logical OR
| is a bit-wise OR
(in this case produce the same result)

Quote:

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Originally Posted by VladimirF

One more:
|| is a logical OR
| is a bit-wise OR
(in this case produce the same result)

---

Yea, I had googled "or" statements. I was feeling more that "||" was the correct use of the "or" statement but I was having a hard time finding "||" as a valid use for "or" or even if it could be used. It also makes sense that it worked that way regardless of which one I used.

Also, this line:

Code:

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std::cin>>a,b;

---

Does not do what you think it does...

Viggy

Quote:

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Originally Posted by MrViggy

Also, this line:

Code:

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std::cin>>a,b;

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Does not do what you think it does...

Viggy

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Yes, I completely rewrote that function. It would have been nice to get it to take both numbers on the same line but I separated it and tossed in a switch for handling the yes or no pieces and error handling.

Quote:

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Originally Posted by fuzzylr

It would have been nice to get it to take both numbers on the same line ...

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Code:

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std::cin >> a >> b;

---

I would like some advice. I would like to reduce the use of goto in this function even though it's fairly simple. What if I wanted to reuse bits and pieces of code? Can I do that or once I get into If / else or While loops do I need to move the code pieces inside the loop till it breaks out or what not. It seems kind of pointless to duplicate the code. I guess that is why the goto is so appealing in this type of instance.

Code:

---

int add()
{
        char answer;
        int a,b;
        int total;

        start:

        std::cout<<"Enter first number: ";
        std::cin>>a;
        std::cout<<"Enter Second number: ";
        std::cin>>b;

        total = a+b;
        std::cout<<"\nSum: "<< total <<"\n\n";

        question:
        std::cout<<"Do you wish to continue: Y/N ";
        std::cin>>answer;

        switch (answer)
        {
                case 'y': goto start;
                case 'Y': goto start;
                case 'n': goto end;
                case 'N': goto end;
                default:
                std::cout<<"Invalid characters.  Use Y/N or y/n.\n\n";
                goto question;
        }

        end:
        std::cout<<"Returning to menu";
        sleep(3);
        return 0;
}

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would it be bad if I did cases like this?

Code:

---

case 'y' || 'Y': code sample here

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My Goal is to consolidate the code down as small as possible while still being functional.

Quote:

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Originally Posted by VladimirF

Code:

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std::cin >> a >> b;

---

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When you do that though. What happens if the user does [23] & [85] but types it out like this "2385"???

Quote:

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Originally Posted by fuzzylr

When you do that though. What happens if the user does [23] & [85] but types it out like this "2385"???

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Did you try?
it will go into the first variable, and will sit there waiting for the second entry.

Quote:

---

Originally Posted by fuzzylr

I would like some advice. I would like to reduce the use of goto in this function even though it's fairly simple. What if I wanted to reuse bits and pieces of code? Can I do that or once I get into If / else or While loops do I need to move the code pieces inside the loop till it breaks out or what not. It seems kind of pointless to duplicate the code. I guess that is why the goto is so appealing in this type of instance.

Code:

---

int add()
{
        char answer;
        int a,b;
        int total;
 
        start:
 
        std::cout<<"Enter first number: ";
        std::cin>>a;
        std::cout<<"Enter Second number: ";
        std::cin>>b;
 
        total = a+b;
        std::cout<<"\nSum: "<< total <<"\n\n";
 
        question:
        std::cout<<"Do you wish to continue: Y/N ";
        std::cin>>answer;
 
        switch (answer)
        {
                case 'y': goto start;
                case 'Y': goto start;
                case 'n': goto end;
                case 'N': goto end;
                default:
                std::cout<<"Invalid characters.  Use Y/N or y/n.\n\n";
                goto question;
        }
 
        end:
        std::cout<<"Returning to menu";
        sleep(3);
        return 0;
}

---

would it be bad if I did cases like this?

Code:

---

case 'y' || 'Y': code sample here

---

My Goal is to consolidate the code down as small as possible while still being functional.

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My god, this is C++ not BASIC. Remove those gotos and replace them with loops and conditionals.
C++ supports 3 types of loop, they are counted (for loop), top tested (while loop ) and bottom tested (do/while loop).

Code:

---

for( int i = 0; i < 10; ++i )
{
  // executed 10 times
}
 
while( variable != value )
{
  // executes while variable is not equal to value
}
 
do
{
 // always executes once, and maybe more
} while ( variable != value );

---

All better choices than a goto!

Quote:

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Originally Posted by fuzzylr

I would like some advice. I would like to reduce the use of goto in this function even though it's fairly simple.

---

No, you should eliminate all of the goto's, not just reduce them.

Secondly, a program riddled with goto's are not "simple". It's simple because you put them in, but most programmers who look at your code will not put any effort into understanding it if it has goto's in it.

Look at this example (not compiled):

Code:

---

#include <iostream>

char getResponse()
{
  char answer;
  bool inputOK = false;
  do
  {
        std::cout<<"Do you wish to continue: Y/N ";
        std::cin>>answer;
        switch (answer)
        {
          case 'y':
          case 'Y':
          case 'n':
          case 'N':
                inputOK = true;
            break;
            default:
                std::cout<<"Invalid characters.  Use Y/N or y/n.\n\n";
        }
    } while ( !inputOK );
    return answer;
}

int add()
{
        char answer;
        int a,b;
        int total;
       
        do
        { 
            std::cout<<"Enter first number: ";
            std::cin>>a;
            std::cout<<"Enter Second number: ";
            std::cin>>b;

            total = a+b;
            std::cout<<"\nSum: "<< total <<"\n\n";
            answer = getResponse();
        } while (answer == 'Y' || answer == 'y');
        std::cout<<"Returning to menu";
        return 0;
}

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Just add a function to get the response. Then the code doesn't turn into spaghetti using goto's.

http://en.wikipedia.org/wiki/Spaghetti_code

Regards,

Paul McKenzie

Quote:

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Originally Posted by Paul McKenzie

No, you should eliminate all of the goto's, not just reduce them.

Secondly, a program riddled with goto's are not "simple". It's simple because you put them in, but most programmers who look at your code will not put any effort into understanding it if it has goto's in it.

Look at this example (not compiled):

Code:

---

#include <iostream>

char getResponse()
{
  char answer;
  bool inputOK = false;
  do
  {
        std::cout<<"Do you wish to continue: Y/N ";
        std::cin>>answer;
        switch (answer)
        {
          case 'y':
          case 'Y':
          case 'n':
          case 'N':
                inputOK = true;
            break;
            default:
                std::cout<<"Invalid characters.  Use Y/N or y/n.\n\n";
        }
    } while ( !inputOK );
    return answer;
}

int add()
{
        char answer;
        int a,b;
        int total;
       
        do
        { 
            std::cout<<"Enter first number: ";
            std::cin>>a;
            std::cout<<"Enter Second number: ";
            std::cin>>b;

            total = a+b;
            std::cout<<"\nSum: "<< total <<"\n\n";
            answer = getResponse();
        } while (answer == 'Y' || answer == 'y');
        std::cout<<"Returning to menu";
        return 0;
}

---

Just add a function to get the response. Then the code doesn't turn into spaghetti using goto's.

http://en.wikipedia.org/wiki/Spaghetti_code

Regards,

Paul McKenzie

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Thank you. That is definitely some food for thought. Great examples.

I used your code as a base. Pretty much used it entirely. For practice. I have seem to hit a snag. Not sure why. The last part of the code is being skipped.

Code:

---

int add()
{
        char answer;
        int a,b;
        int total;

        do
        {
                std::cout<<"Enter first number: ";
                std::cin>>a;
                std::cout<<"Enter Second number: ";
                std::cin>>b;

                // Add to Int's together.
                total = a+b;
                std::cout<<"\nSum: "<< total <<"\n\n";

                answer = getResponse();
        } while (answer == 'Y' || answer == 'y');
        std::cout<<"Returning to menu";
        sleep(3);
        return 0;
}

---

This code is only partically being processed...

Code:

---

while (answer == 'Y' || answer == 'y');
        std::cout<<"Returning to menu"; <---- this piece
        sleep(3);
        return 0;
}

---

What is odd is the sleep is being processed but the cout is not.

std::cout<<"Returning to menu" << std::endl;

Quote:

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Originally Posted by Richard.J

std::cout<<"Returning to menu" << std::endl;

---

Is there any difference between

Code:

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std::endl

---

and

Code:

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\n

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When should which be used?

http://www.cplusplus.com/forum/beginner/7350/

I found the link above but I can't seem to find anything saying that they are really all that different.

they both add a newline to the buffer, but std::endl flushes the buffer. I.e. when using \n, you'll never know when the buffer is actually sent to the console (assuming std::cout is used) whereas std::endl enforces this.

Quote:

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Originally Posted by Richard.J

they both add a newline to the buffer, but std::endl flushes the buffer. I.e. when using \n, you'll never know when the buffer is actually sent to the console (assuming std::cout is used) whereas std::endl enforces this.

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Thank you very much.

Quote:

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Originally Posted by fuzzylr

This code is only partically being processed...

Code:

---

while (answer == 'Y' || answer == 'y'); <---- semi colon here is bad
        std::cout<<"Returning to menu"; <---- this piece
        sleep(3);
        return 0;
}

---

What is odd is the sleep is being processed but the cout is not.

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.....

In most cases it doesn't really matter when the output buffer gets flushed, since it will certainly be flushed at the end of the program or upon trying to get any user input. There are a few cases where it does matter (inter-process communication, for instance), so it's good to know what flushing is all about.

Quote:

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Originally Posted by Amleto

.....

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Yes it does belong there. It will throw compiler errors or should I say it did toss compiler errors.

also note stated reference below that do-while loops are built that way.

http://www.cplusplus.com/doc/tutorial/control/