Code from text not working

[mushroom000]

Is this because Im using Dev-C++ 4.9.9.2? Is Dev-C++ a good IDE to use for C++?


#include <iostream> // allows program to perform input and output

using std::cout; // program uses cout
using std::cin; // program uses cin
using std::endl; // program uses endl

// function main begins program execution
int main()
{
int number1; // first integer to compare
int number2; // second integer to compare

cout << "Enter two integers to compare: "; // prompt user for data

cin >> number1 >> number2; // read two integers from user

if ( number1 == number2 )
cout << number1 << " == " << number2 << endl;

if ( number1 != number2 )
cout << number1 << " != " << number2 << endl;

if ( number1 < number2 )
cout << number1 << " < " << number2 << endl;

if ( number1 > number2 )
cout << number1 << " > " << number2 << endl;

if ( number1 <= number2 )
cout << number1 << " <= " << number2 << endl;

if ( number1 >= number2 )
cout << number1 << " >= " << number2 << endl;

cin.get();

return 0; // indicate that program ended successfully

} // end function main

[mushroom000]

I believe the problem is in the following line:

cin >> number1 >> number2;

I think that's where the problem lies because if I give number1 a value when it is declared, the code works.

[Zhuge]

What is happening instead of what you are expecting? And use code tags please.

[mushroom000]

Sorry, I dont know what a code tag is. The program just opens and closes right away. I pretty much want to know how to get input from the user and store them under variables.

[mushroom000]

Oh, I think I figured out how to use a code tag.

[mushroom000]

Im pretty sure Dev-C++ isnt recognizing the "cin" command.

[buffbill]

Its quite possible that cin.get(); is not keeping the DOS window open.
Try:

char q;
cin>>q;
return o;
}

[helios]

http://www.cplusplus.com/forum/beginner/1988/

[xitan]

quick question, is it necessary to have:

using std::cout; // program uses cout
using std::cin; // program uses cin
using std::endl; // program uses endl 

in your program? i think if you use using namespace std; after your include, it will save you lines of code and unnecessary typing. I could be wrong. Also, after the user initializes the variable, and you apply the value the user assigned to the variable, i usually add cin.ignore(); after it. cin.ignore(); ignores the enter key, because the enter key is used to shut down the program. So I'd place it right after cin >> number1 >> number2;, on a new line. I also use Dev-C++ and I had that problem the first time. Please, if I am wrong someone correct me. I am new to C++.

EDIT: Tested with cin.ignore(); and worked.

[bluezor]

@xitan

It's just better to use what you need from the namespace, rather than use the whole namespace itself since it can cause some errors.

[z05DSL3A]

about namespace using declarations
http://www.cplusplus.com/forum/beginner/9181/

[xitan]

ok so:

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

int main()
{
    int x;
    
    std::cout << "Please enter a integer type number." << endl;
    std::cin >> x;
    std::cout << "The integer type number you entered is: " << x << endl;
    std::cin.ignore();
    
    std::cin.get();
    return (0);
}

would be a good example of declaring standards from the include that will only be used correct? im not sure of lines 10-13, if it's necessary to include std:: before the statement.

[Beibin]

In lines 2-4, you have already introduced cin, cout and endl from the std namespace into global variable scope, so you can use them directly, as you have done with endl.

[xitan]

@Beibin would it make a difference if i introduced them as local? and if i did, in the sample program above, i would just declare them within the main function correct?

[helios]

I'm not sure that's possible, but why would you want to do that?

[Beibin]

It is possible:

#include <iostream>

void testFunction(void);

int main(void)
{
  using std::cout;
  cout << "cout from main()\n\n";
  testFunction();
  std::cin.ignore();
  return 0;
}

void testFunction(void)
{
  /*
   * Compile-time error:
   *
   * In function `void testFunction()':
   * `cout' was not declared in this scope
   */
  cout << "cout from testFunction()\n\n";
}

Here, cout was introduced only inside the main function, not globally. Therefore, trying to access it outside of main will prevent you from compiling the program.

[xitan]

@Beibin Wow, thanks, very clear example. Exactly what I was looking for. Thanks man.