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# C++ Namespaces Consider a situation where there are two students in a class with the same name "Zara". To distinguish them, we need to use some additional information along with their names, such as their home address or their parents' names, etc. A similar situation arises in C++ applications. For example, you might write a function named `xyz()`, and there might also be an identical function `xyz()` available in another library. In this case, the compiler would be unable to determine which `xyz()` function you are referring to. Therefore, the concept of **namespaces** was introduced to solve this problem. Namespaces serve as additional information to distinguish between functions, classes, variables, etc., with the same name in different libraries. Using a namespace defines the context. Essentially, a namespace defines a scope. Let's take an example from a computer system: a folder (directory) can contain multiple subfolders. Each subfolder cannot have files with the same name, but files in different subfolders can have the same name. !(#) ## Defining a Namespace A namespace is defined using the keyword **namespace**, followed by the namespace name, as shown below: namespace namespace_name{// code declarations} To call a function or variable within a namespace, you need to prefix it with the namespace name, as shown below: name::code; // code can be a variable or function Let's see how namespaces define the scope for entities like variables or functions: ## Example #includeusing namespace std; // first namespace namespace first_space{void func(){cout<<"Inside first_space"<<endl; }}// second namespace namespace second_space{void func(){cout<<"Inside second_space"<<endl; }}int main(){// call function from first namespace first_space::func(); // call function from second namespace second_space::func(); return 0; } When the above code is compiled and executed, it produces the following result: Inside first_space