Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
What is Array Decay in C++?
The loss of type and dimensions of an array is known as array decay. It occurs when we pass the array into a function by pointer or value. First address is sent to the array which is a pointer. That is why, the size of array is not the original one.
Here is an example of array decay in C++ language,
Example
#include<iostream>
using namespace std;
void DisplayValue(int *p) {
cout << "New size of array by passing the value : ";
cout << sizeof(p) << endl;
}
void DisplayPointer(int (*p)[10]) {
cout << "New size of array by passing the pointer : ";
cout << sizeof(p) << endl;
}
int main() {
int arr[10] = {1, 2, };
cout << "Actual size of array is : ";
cout << sizeof(arr) <endl;
DisplayValue(arr);
DisplayPointer(&arr);
return 0;
}Output
Actual size of array is : 40 New size of array by passing the value : 8 New size of array by passing the pointer : 8
To prevent array decay
There are two following ways to prevent the array decay.
Array decay is prevented by passing the size of array as a parameter and do not use sizeof() on parameters of array.
Pass the array into the function by reference. It prevents the conversion of array into pointer and it prevents array decay.
Here is an example of preventing array decay in C++ language,
Example
#include<iostream>
using namespace std;
void Display(int (&p)[10]) {
cout << "New size of array by passing reference: ";
cout << sizeof(p) << endl;
}
int main() {
int arr[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
cout << "Actual size of array is: ";
cout << sizeof(arr) <<endl;
Display(arr);
return 0;
}Output
Actual size of array is: 40 New size of array by passing reference: 40
Updated on: 24-Jun-2020
2K+ Views
Advertisements