Dynamic Allocation of the Array

Before we explore why dynamic allocation is necessary, let's quickly recap the characteristics of static and dynamic arrays:

Fixed Size: Once declared, the size of a static array is fixed and cannot be changed during runtime;
Memory Allocation at Compile Time: The memory required for a static array is allocated at compile time.

Resizable: Dynamic arrays allow for resizing during runtime, providing flexibility to adapt to changing program requirements;
Memory Allocation at Runtime: Memory for dynamic arrays is allocated during program execution.

The Limitations of a Static Approach

Consider the program that prompts the user to input performance scores for each day that has passed in current month.

Unfortunately, we can't achieve this using a static array:

main


              12345678910
            
#include <iostream>
#include <ctime>

int main() {
    std::time_t currentTime = std::time(nullptr);
    int day_passed = std::localtime(&currentTime)->tm_mday;
    
    int arr[day_passed];
    std::cout << day_passed << std::endl; 
}

Note

This will generate a compilation error because day_passed is not a constant expression it depends on the runtime value of the current day of the month.

So instead of static array we have to use a dynamic allocated array.

Tarefa

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Create a dynamic array with a size equivalent to the number of days that have passed.
Free allocated memory.

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Seção 4. Capítulo 3

Dynamic Allocation of the Array

Before we explore why dynamic allocation is necessary, let's quickly recap the characteristics of static and dynamic arrays:

Fixed Size: Once declared, the size of a static array is fixed and cannot be changed during runtime;
Memory Allocation at Compile Time: The memory required for a static array is allocated at compile time.

Resizable: Dynamic arrays allow for resizing during runtime, providing flexibility to adapt to changing program requirements;
Memory Allocation at Runtime: Memory for dynamic arrays is allocated during program execution.

The Limitations of a Static Approach

Consider the program that prompts the user to input performance scores for each day that has passed in current month.

Unfortunately, we can't achieve this using a static array:

main


              12345678910
            
#include <iostream>
#include <ctime>

int main() {
    std::time_t currentTime = std::time(nullptr);
    int day_passed = std::localtime(&currentTime)->tm_mday;
    
    int arr[day_passed];
    std::cout << day_passed << std::endl; 
}

Note

This will generate a compilation error because day_passed is not a constant expression it depends on the runtime value of the current day of the month.

So instead of static array we have to use a dynamic allocated array.

Tarefa

Swipe to show code editor

Create a dynamic array with a size equivalent to the number of days that have passed.
Free allocated memory.

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Tudo estava claro?

Obrigado pelo seu feedback!

Seção 4. Capítulo 3

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