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.cpp
12345678910#include <iostream> #include <ctime> int main() { std::time_t currentTime = std::time(nullptr); int day_passed = std::localtime(¤tTime)->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.
Swipe to start coding
Imagine you are working as a meteorologist who needs to analyze temperature readings throughout the day.
You will work with pointers and functions that manipulate dynamically allocated arrays of data.
- Initialize variables
sumto 0,minTempto the first element of the array, andmaxTempto the first element of the array. - Iterate through the array
tempsusing aforloop with an indexifrom 0 tohours. - For each element
temps[i], add its value tosum. - If
temps[i]is less thanminTemp, assigntemps[i]tominTemp. - If
temps[i]is greater thanmaxTemp, assigntemps[i]tomaxTemp. - Calculate the average temperature by dividing
sumbyhoursand store it in a variableaverage. - Print the values of
minTemp,maxTemp, andaverageto the console.
Solução
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Dynamic Allocation of the Array
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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.cpp
12345678910#include <iostream> #include <ctime> int main() { std::time_t currentTime = std::time(nullptr); int day_passed = std::localtime(¤tTime)->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.
Swipe to start coding
Imagine you are working as a meteorologist who needs to analyze temperature readings throughout the day.
You will work with pointers and functions that manipulate dynamically allocated arrays of data.
- Initialize variables
sumto 0,minTempto the first element of the array, andmaxTempto the first element of the array. - Iterate through the array
tempsusing aforloop with an indexifrom 0 tohours. - For each element
temps[i], add its value tosum. - If
temps[i]is less thanminTemp, assigntemps[i]tominTemp. - If
temps[i]is greater thanmaxTemp, assigntemps[i]tomaxTemp. - Calculate the average temperature by dividing
sumbyhoursand store it in a variableaverage. - Print the values of
minTemp,maxTemp, andaverageto the console.
Solução
Obrigado pelo seu feedback!
single