Command not found

[AAAbb7]

When I try to run my code and I input "B" or "b4" it always just tells me "command not found" in the terminal. Its supposed to have a "0" or "1" output. Does anybody know what is wrong?

  
#include <iostream>
#include <cassert>
using namespace std;

int isValidNote(string note)
{
    
    if (note.length()!= 2)
    {
        return false;
    }
    else if ((note[0] >='A' && note[0] <='G') && (note[1] >='0' && note[1] <='9'))
    {
        return true;
    }
    return 0;
}

int main ()
{
    assert(isValidNote("A7") == true);
    assert(isValidNote("B") == false);
    
    return 0;
}

[deleted account xyzzy]

You are misunderstanding how assert works. It doesn't display a message, it simply aborts program execution when the tested condition fails.
https://en.cppreference.com/w/cpp/header/cassert

Plus the assert macro relies on another macro NDEBUG to work. A non-standard macro.

With Visual Studio assert can be triggered when the code is compiled in debug mode. Release mode and assert is ignored.

Now, you can have the macro display a message, you have to write it. It is non-standard to do so.
https://en.cppreference.com/w/cpp/error/assert

Plus returning an int value when a Boolean is expected is potentially unsafe.

#include <iostream>
#include <cassert>
#include <string>  // use a C++ string, need this

bool isValidNote(std::string note)
{
   if (note.length() != 2)
   {
      return false;
   }
   else if ((note[0] >= 'A' && note[0] <= 'G') && (note[1] >= '0' && note[1] <= '9'))
   {
      return true;
   }
   return false;
}

int main()
{
   assert(isValidNote("A7") == true);
   assert(isValidNote("B") == false);
}

FYI, both assertions pass.

A7 because two characters consisting a letter and a number is true. true == true.

B because it is a single letter. false == false.

No output.

Change either test condition, A7 == false or B == true, and their respective assert should trigger. It happens with VS in debug mode, as expected.

If both are false, then the first one will trigger. The 2nd is never reached.

[AAAbb7]

Thank you! That makes a lot of sense. :D

[deleted account xyzzy]

static_assert might be a better fit, it shows at compile-time if the assertion fails. Debug or release mode.

Requires C++11 or later to work, no library needed.
https://en.cppreference.com/w/cpp/language/static_assert

#include <iostream>
#include <string>  // use a C++ string, need this

bool constexpr isValidNote(std::string note)
{
   if (note.length() != 2)
   {
      return false;
   }
   else if ((note[0] >= 'A' && note[0] <= 'G') && (note[1] >= '0' && note[1] <= '9'))
   {
      return true;
   }
   return false;
}

int main()
{
   static_assert(isValidNote("A7") != true);
   static_assert(isValidNote("B") != false);
}

Both assertions fail. In VS the failures show up as errors without needing to compile.

Do note the function has to be declared as constexpr or static_assert will not work.

And declaring the function as constexpr bool isValidNote(std::string note) works as well.