Namespace concept and std usage in C++ - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to use the standard namespace prefix for cout.

C++

#include <iostream>
int main() {
    [1]::cout << "Hello, world!" << std::endl;
    return 0;
}

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Anamespace

Busing

Ccout

Dstd

Attempts:

3 left

💡 Hint

Common Mistakes

Writing 'using::cout' instead of 'std::cout'.

Forgetting the namespace prefix and writing just 'cout'.

The std namespace contains standard library features like cout. Prefixing with std:: accesses them.

2fill in blank

medium

Complete the code to bring all standard names into the current scope.

C++

#include <iostream>
[1] std;
int main() {
    cout << "Welcome!" << endl;
    return 0;
}

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Ausing namespace

Bnamespace

Cusing

Dinclude

Attempts:

3 left

💡 Hint

Common Mistakes

Writing only 'using std;' which is incomplete.

Writing 'namespace std;' which declares a namespace, not bring it into scope.

The statement using namespace std; allows using standard library names without the std:: prefix.

3fill in blank

hard

Fix the error in the code to correctly use the standard vector.

C++

#include <vector>
int main() {
    std::[1]<int> numbers = {1, 2, 3};
    return 0;
}

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AVector

Bvector

Cvect

Dlist

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Vector' with uppercase V which is not defined in std.

Using 'vect' which is not a standard container.

The correct standard container for a dynamic array is std::vector with a lowercase 'v'.

4fill in blank

hard

Fill both blanks to define and use a custom namespace with a function call.

C++

#include <iostream>
namespace [1] {
    void greet() {
        std::cout << "Hi from namespace!" << std::endl;
    }
}

int main() {
    [2]::greet();
    return 0;
}

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Acustom

Bstd

Dmain

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for the namespace definition and call.

Calling greet without the namespace prefix.

The namespace is named custom. To call the function, prefix it with the same namespace name.

5fill in blank

hard

Fill all three blanks to create a namespace alias and use it to print a message.

C++

#include <iostream>
namespace [1] = std;

int main() {
    [2]::cout << "Alias works!" << [3];
    return 0;
}

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As

Cstd::endl

Dendl

Attempts:

3 left

💡 Hint

Common Mistakes

Using different alias names in definition and usage.

Using 'endl' without the namespace or alias prefix.

We create an alias s for std. Then use s::cout and end the line with std::endl.