Namespaces

Namespaces allow grouping variables, functions, and types under a name, preventing name conflicts between different parts of the code or libraries.

Definition and usage

namespace group {
    int var1 = 10;  // Variable in the group namespace
}
 
namespace another_group {
    double var2 = 2.3; // Variable in the another_group namespace
}

To access variables from a namespace, use the namespace:: prefix:

auto variable1 = group::var1;
double variable2 = another_group::var2; // Access variable from another namespace

Using namespace

Allows using variables from a namespace without the prefix:

using namespace group; // Use variables from group namespace without the group:: prefix
int var3 = var1;       // var1 from the group namespace

Note

std (from the standard library) is a namespace. Types like std::string, std::vector, or std::cout use the std:: prefix precisely because of this.

Warning

Avoid overusing using namespace in large programs: it can cause ambiguities when two namespaces define the same name.

Next: Exceptions and Errors