Home/ Questions/Q 3333720
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-17T23:49:39+00:00

In C++, how to deal with NULL values in a context where we might

  • 0

In C++, how to deal with NULL values in a context where we might expect a string or an integer?

Typically, the context would be when retrieving data from a database, e.g. with a LEFT JOIN where some non-existing values in some column would be represented by a NuLL value instead of the expected string or integer.

Strong casting in C++ makes this type of scenario much more difficult to deal with than with PHP.

In PHP, we can easily have a if/else switch using the === operator:

if ($value === NULL) {
  // No data.
} else {
  // We have some valid data.
}

What would the equivalent look like in C++?

I’ve searched and couldn’t find a C++ relevant question.

The question is valid in general. In my particular case, I am using the dbixx SQL library.

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    It may sound like a general concept, but there is no general answer for C++. The language itself does not have a truly general “NULL” value that can by used with all types to distinguish from having been set to an actual value.

    So the answer in any situation entirely depends on the library or whatever that you’re working with and how it has been designed to indicate “NULL” values. The return values of functions used to access the data may perhaps indicate whether the data is NULL or otherwise. Or there may be something like a separate IsNull() function. Or the library may use some other different scheme. There are many possibilities.

    The only possible general answer is: read the documentation of the library to find out how they specifically deal with it.

    • 0