Aprenda Modifying Array Values | Using Arrays in Programs

Arrays in C++ are not just for storing data—you can also change their contents as your program runs. Modifying array elements is essential for many tasks, such as updating scores, tracking inventory, or performing calculations on sets of numbers. To change the value of a specific element, you use its index and the assignment operator (=). This allows you to update data in-place and use updated values for further processing or output.

main.cpp


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#include <iostream>

int main()
{
    int numbers[5] = {1, 2, 3, 4, 5};

    // Double each value in the array
    for (int i = 0; i < 5; ++i)
        numbers[i] = numbers[i] * 2;

    // Print the modified array
    for (int i = 0; i < 5; ++i)
        std::cout << numbers[i] << " ";
    
    std::cout << std::endl;
}

In this example, you start with an array of five integers. The loop goes through each index from 0 to 4, and on each pass, the value at that index is replaced with its double. The assignment numbers[i] = numbers[i] * 2; takes the current value, multiplies it by 2, and stores the result back into the same position. After the loop, the array holds the values 2, 4, 6, 8, and 10, which are then printed to the console. Assigning to array elements in this way lets you update data based on calculations or other logic.

main.cpp


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#include <iostream>

int main()
{
    int arr[4] = {7, 8, 9, 10};

    // Set all elements to zero
    for (int i = 0; i < 4; ++i)
        arr[i] = 0;

    // Print the array to check the result
    for (int i = 0; i < 4; ++i)
        std::cout << arr[i] << " ";
    std::cout << std::endl;
}

When changing array values, it is important to use the correct index. If you accidentally use the wrong index, you might overwrite the wrong element or even access memory outside the array, leading to bugs or crashes. Always make sure your loops start at 0 and stop before the array's size, and double-check which index corresponds to the element you want to change.

Note

Always check your loop indices to ensure you are modifying the intended elements.

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Seção 3. Capítulo 2

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main.cpp


              12345678910111213141516
            
#include <iostream>

int main()
{
    int numbers[5] = {1, 2, 3, 4, 5};

    // Double each value in the array
    for (int i = 0; i < 5; ++i)
        numbers[i] = numbers[i] * 2;

    // Print the modified array
    for (int i = 0; i < 5; ++i)
        std::cout << numbers[i] << " ";
    
    std::cout << std::endl;
}

main.cpp


              123456789101112131415
            
#include <iostream>

int main()
{
    int arr[4] = {7, 8, 9, 10};

    // Set all elements to zero
    for (int i = 0; i < 4; ++i)
        arr[i] = 0;

    // Print the array to check the result
    for (int i = 0; i < 4; ++i)
        std::cout << arr[i] << " ";
    std::cout << std::endl;
}

Note

Always check your loop indices to ensure you are modifying the intended elements.

Tudo estava claro?

Obrigado pelo seu feedback!

Seção 3. Capítulo 2