Thread: Atoi and such

I made a certain program and I am now trying to get rid of some annoying little bugs. Going to post a part of the code so you guys can help me out .

Code:

#include <iostream

int main()
{
    cout<<"1- New Game" <<endl;
    cout<<"2- Exit" <<endl;
    cout<<"Choose your option: " <<endl;

    bool ValidOption = false;


    while (ValidOption != true)
    {

       char option[100];
       cin.clear();
       cin>>option;

       int int_option = atoi(option);

       switch (int_option)
       {
       case 1:
           ValidOption = true;
           cout<<"ok.";
       case 2:
           ValidOption = true;
           cout<<"ok";
       default:
           ValidOption = false;
           cout<<"Error: ";
           break;
      }
   }
}

Ok so the code above displays a simple menu and it will display "ok" whether you insert "1" or "2".
Now if you are to insert a char, string or anything else it will work, unless you separate it by a space. The loop will run twice considering cin stops at spaces (Which means it will display "error:" twice). Can anyone help me?

Example:

1- New Game
2- Exit
Choose your option: 3
Error: 4
Error: gfgdg
Error: ad
Error:^Z
Error:adsad adada
Error: Error: 1
"ok"

You forgot the break statement on each of your case statements.


Jim

I only started manipulating atoi today so I'm not exacly sure as to how it works.

My first thought was to define the array as string (string option[100]) and convert the string into an integer, yet atoi did not seem to work that way:

Code:

       string option[100];
       cin.clear();
       getline(cin,option[100]);
 
       int int_option = atoi(option);

> int int_option = atoi(option);
Invalid code right here because "std::string is incompatible with parameter of type const char".

Is there something else I should include? Because

>std::stringstream extractor(option);
Error:Incomplete type is not allowed (extractor is underlined)

>extractor >> int_option;
Error:no operator matches these operands; (>> underlined)

Originally Posted by Neo1

Prefer the C++11 way:

Code:

MyString = std::to_string(option);

except the OP is actually trying to go the other way, so elysia's method is correct, in the absence of boost::lexical_cast.

Or he could use the stoi() function instead of atoi().

Jim

Originally Posted by Elysia

Try:

Code:

std::string option;
std::cin.clear();
std::getline(std::cin, option);

int int_option;
std::stringstream extractor(option);
extractor >> int_option;

Exacly what I was looking for. Dem bugs are all gone. tyvm.

@Jim: Your solution makes sense as well, ty.

Considering I might use it with some frequence I would like to know what these lines of code do exacly:

> std::stringstream extractor(option);

> extractor >> int_option;

Did you try to Google std::stringstream? This is a class that associates the string (option) with a stream (extractor) once this stream is created you use it just as you would cout or cin.

Jim