Arrays in C++ - Reading Assignment

[sandrau]

1. What is an array? It is a variable that can store multiple values.
   An array is an indexed collection of data elements of the same type.

2. Which index would you use to access the second variable in an array ? A second loop should print the values of the array with spaces between the values. Activity: Initialize …

3. What can you say about the size of an array?
   The length of an array is established when the array is created. After creation, its length is fixed. To determine the size of your array in bytes, you can use the size of operator: int a[17]; size_t n = sizeof(a)

4. How can you initialize an array?
   With normal variables, we could declare on one line, then initialize on the next:
   int x;
   x = 0;
   Or, we could simply initialize the variable in the declaration statement itself:
   int x = 0;

5. How can you get the size of an array in bytes? To determine the size of your array in bytes, you can use the size of operator: int a[17]; size_t n = sizeof(a);

6. How can you use the function size of in order to calculate the number of elements in an array?
   To determine the number of elements in the array, we can divide the total size of the array by the size of the array element. You could do this with the type, like this: int a[17]; size_t n = sizeof(a) / sizeof(int);

7. What happens when you try to write outside the bounds of the array?
   If you read or write outside of an array’s bounds, you may read or write garbage or (if you are lucky) you may get a segmentation fault which at least tells you there’s a problem. In the end, it is up to you to make sure that your program respects the bounds of its arrays.

[Alko89]

@sandrau

A second loop should print the values of the array with spaces between the values.

You can access the second element in the array with arrayName[1]

@sandrau

int x;
x = 0;
Or, we could simply initialize the variable in the declaration statement itself:
int x = 0;

You can initialize an array one by one or with a initializer list int array[] = {1, 2, 3}

[camarosan]

What is an array?
storage in one variable many variables. You can access every variable by the index
Which index would you use to access the 2nd variable in an array?
array[1]
What can you say about the size of an array?
Is fixed or dynamic

Second part
How can you initialize an array?
there are several ways but the easier for me is
int array [] = {2,23,4,5,6} // 5 variables
How can you get the size of an array in bytes?
sizeoff(array)
How can you use the function sizeof in order to calculate the number of elements in an array?
sizeoff(array)/sizeof(array[0])
What happens when you try to write outside the bounds of the array?
Unidentified behavior

[NLUGNER]

Q.)What is an array?
A.) An array is a collection of elements of the same type placed in contiguous memory locations that can be individually referenced by using an index to a unique identifier. … As expected, an n array must be declared prior its use. A typical declaration for an array in C++ is: type name [elements];
Q.)Which index would you use to access the 2nd variable in an array?
A.) [1]
Q.)What can you say about the size of an array in bytes?
A.) The size of an array object is always equal to the second template parameter used to instantiate the array template class (N). Unlike the language operator sizeof, which returns the size in bytes, this member function returns the size of the array in terms of number of elements.

Q.)How can you initialize an array?
A.)The initializer for an array is a comma-separated list of constant expressions enclosed in braces ( { } ). The initializer is preceded by an equal sign ( = ). You do not need to initialize all elements in an array.

Q.)How can you get the size of an array in bytes?
A.)To determine the size of your array in bytes, you can use the sizeof operator: int a[17]; size_t n = sizeof(a); On my computer, ints are 4 bytes long, so n is 68. To determine the number of elements in the array, we can divide the total size of the array by the size of the array element.

Q.)How can you use the function sizeof in order to calculate the number of elements in an array?
A.)The sizeof for a struct is not always equal to the sum of sizeof of each individual member. This is because of the padding added by the compiler to avoid alignment issues. Padding is only added when a structure member is followed by a member with a larger size or at the end of the structure.

Different compilers might have different alignment constraints as C standards state that alignment of structure totally depends on the implementation.

Q.) What happens when you try to write outside the bounds of the array?
a. ) you get bufferoverflow which results in crazy and unpredictable behaviour. Buffer overflows are one of the oldest and most common causes for arbitrary code execution vulnerabilities, and applications written in programming languages like C and C++ are more prone to such coding mistakes than other languages. To minimize the risk. always do the coding in debug mode and the release in production mode to avoid undefined behaviour as much as possible.

[SimpleSimon]

Q1. What is an array?

A1. An array is an aggregate data type that allows the storage and access to variables of the same type via a single identifier - i.e. a list of variables/elements

Q2. Which index would you use to access the 2nd variable in an array?

A2. 1 e.g. theArray[1]

Q3. What can you say about the size of an array?

A3. The size - also known as the length - of an array equates/refers to the number of elements/variables that it contains

Q4. How can you initialize an array?

A4. Code example (fixed array):

int arr[] = {10,20,30,40,50,60};

alternatively, elements can be initialized one-by-one e.g.

int myArray[5]; // hold the first 5 prime numbers

myArray[0] = 2;

myArray[1] = 3;

myArray[2] = 5;

myArray[3] = 7;

myArray[4] = 11;

Q5. How can you get the size of an array in bytes?

A5. Code example:

sizeof(array)

Q6. How can you use the function sizeof in order to calculate the number of elements in an array?

A6. Code example:

int arr[] = {10,20,30,40,50,60};

int arrSize = sizeof(arr)/sizeof(arr[0]);

cout << "The size of the array is: " << arrSize;

Q7. What happens when you try to write outside the bounds of the array?

A7. Writing outside the bounds of an array range will cause unidentified behavior

[Vote3rdParty]

PART A -
1: " An array is an aggregate data type that lets us access many variables of the same type through a single identifier." - https://www.learncpp.com/cpp-tutorial/61-arrays-part-i/
2. Index 1 is used to access the 2nd variable in an array.
3. "“The length of an array must be known at compile time, compile-time constant.” - https://www.learncpp.com/cpp-tutorial/61-arrays-part-i/

PART B:
1: You can initialize arrays one by one or by using initializer lists.
2: To get the size of an array in bytes you can use std::size, or if you need a signed size and are using C++20 you can use std::ssize (signed size).
3. sizeof(array[0])
4. When you write outside the bounds of an array you get undefined behavior.

[Alko89]

@Vote3rdParty

2: To get the size of an array in bytes you can use std::size

This will give you the number of elements in the array, sizeof gives you the length in bytes.

@Vote3rdParty

3. sizeof(array[0])

This will only give you the size (in bytes) of one element. To get the length of the array you must then divide the number with the entire array: sizeof(array) / sizeof(array[0]).

[Filipe_Venancio]

1. What is an array?
   An array is an aggregate data type that lets us access many variables of the same type through a single identifier.

2. Which index would you use to access the 2nd variable in an array?
   Arrays start from 0, the answer is 1.

3. What can you say about the size of an array?
   The size or length of an array is N, where N is the number of elements provided to the array.

4. How can you initialize an array?
   In an array variable declaration, we use square brackets ([]) to tell the compiler both that this is an array variable. Ex.: int arrN[3] = {1, 2, 3}

5. How can you get the size of an array in bytes?
   using sizeof(array)

6. How can you use the function sizeof in order to calculate the number of elements in an array?
   Example:
   int arrN[] = { 1, 1, 2, 3, 5, 8, 13, 21 };
   int arrNSize = sizeof(arrN)/sizeof(arrN[0]);
   cout << "Array size = " << arrNSize;

7. What happens when you try to write outside the bounds of the array?
   I’ll get unidentified behavior.

[acf]

Part 1:

1. An array is an aggregate data type that lets us access many variables of the same type through a single identifier.

2. Index 1

3. The size of an array is the total number of variables held in an array.

Part 2:

1. Array names Array 1 of length 4 with initialized variables example: Array1[3]={0,1,2,3,4};

2. Array length multiplied by element size.

3. array length = sizeof(array) / sizeof(array[0])

4. Undefined behavior.

[reisnertobias]

1. What is an array?

an index of objects
2. Which index would you use to access the 2nd variable in an array?
[1]
3. What can you say about the size of an array?
seize of an array = array length * element size

1. How can you initialize an array?

by defining the values or a list.

2. How can you get the size of an array in bytes?

number of total integers times 4.
3. How can you use the function sizeof in order to calculate the number of elements in an array?

sizeof(array)/sizeof[0])
4. What happens when you try to write outside the bounds of the array?
will cause an unpredictable result because the memory location outside of the scope will be written.

[Alko89]

@reisnertobias

number of total integers times 4.

You get the size by using sizeof

@reisnertobias

sizeof(array)/sizeof[0])

Were you in a hurry? You need to divide with the first (because you can be sure it exists) of the array, using sizeof[0] will probably throw an error.

[Rigel12]

@ivan

What is an array?

An array is an aggregate data type that lets us access many variables of the same type through a single identifier.

@ivan

Which index would you use to access the 2nd variable in an array?

1

@ivan

What can you say about the size of an array?

Fixed arrays cannot have a length based on either user input or some other value calculated at runtime. Fixed arrays have a fixed length that can not be changed.

The length of a dynamic array can be set at runtime, and their length can be changed.

Part 2

@ivan

How can you initialize an array?

An array can be initialized element by element or by using an initializer list.

@ivan

How can you get the size of an array in bytes?

sizeof()

@ivan

How can you use the function sizeof in order to calculate the number of elements in an array?

array length = sizeof(array) / sizeof(array[0])

@ivan

What happens when you try to write outside the bounds of the array?

Undefined behavior.

[CaliCrypto22]

1. What is an array?
   A: An array is an aggregate data type that lets programmers access many variables of the same type through a single identifier.

2. Which index would you use to access the 2nd variable in an array?
   A: You would use index #1.

3. What can you say about the size of an array?
   A: For fixed arrays, the size must be declared before compiling. In other words, the length of a fixed array must be known at compile time.

4. How can you initialize an array?
   A: One way to “initialize” an array is to do it element by element. However, this can be a pain if the array is a long one. Fortunately, C++ provides a more convenient way to initialize entire arrays via use of an “initializer list” (putting the elements of the array in between curly brackets).

5. How can you get the size of an array in bytes?
   A: sizeof(array)

6. How can you use the function sizeof in order to calculate the number of elements in an array?
   A: array length = sizeof(array) / sizeof(array[0])

7. What happens when you try to write outside the bounds of the array?
   A: You will get undefined behavior. For example, this could overwrite the value of another variable, or cause your program to crash.

[PapatoniC]

1. What is an array?
It is a collection of variables of the same type that can be accessed through a single identifier

2. Which index would you use to access the 2nd variable in an array?
1
3. What can you say about the size of an array?
It is the number of variables that the array contains

1. How can you initialize an array?
   By assigning individually every variable a value like variable[N]=value or all values together variable[MaxArray]{ 2, 3, 5, 7, 11 };
2. How can you get the size of an array in bytes?
   sizeof(array)
3. How can you use the function sizeof in order to calculate the number of elements in an array?
   TotalElements = sizeof(array)/sizeof(arrayType)
4. What happens when you try to write outside the bounds of the array?
   The application crash , as the system do not not how to handle this exception.

[waka]

Part 1

1. An array is an aggregate data type that lets us access many variables of the same type through a single identifier.
2. 1
3. When you define an array, it has a fixed size.

Part 2

1. Entire arrays can be initialized via an initializer list (e.g. int prime[5]{ 2, 3, 5, 7, 11 };) or less efficiently element by element.
2. sizeof()
3. Divide the output of sizeof(array) by the size of an element.
4. You will get undefined behavior – For example, this could overwrite the value of another variable, or cause your program to crash.

[SabineB]

1st part

1. An array is an aggregate data type that lets us access many variables of the same type through a single identifier.
2. Index [1]
3. The length (count of elements) is known when array is being defined.

2nd part

1. Arrays can be initialized element by element or using initializer list.
2. With function std::size()
3. By dividing the size of the entire array by the size of an array element:
   sizeof(array) / sizeof(array[0])
   This has to be done like this, because function sizeof() gives the size of the array multiplied by the size of an int
4. Undefined behavior

[Alko89]

@SabineB

With function std::size()

This would give you the length of the array (number of elements), sizeof gives you the size in bytes.

[serba]

@ivan

Part 1:
1. What is an array?
2. Which index would you use to access the 2nd variable in an array?
3. What can you say about the size of an array?

Part 2:
1. How can you initialize an array?
2. How can you get the size of an array in bytes?
3. How can you use the function sizeof in order to calculate the number of elements in an array?
4. What happens when you try to write outside the bounds of the array?

Part 1:

• What is an array?
  An array is an aggregate date type which allows us to access many variables of the same type (related) with a single identifier…

• Which index would you use to access the 2nd variable in an array?
  array[1];

• What can you say about the size of an array?
  If the size or length of an array is known at compile time, it is called a fixed array. Fixed arrays have a fixed length and cannot be changed.

Part 2:

• How can you initialize an array?
  You can initialize an array by each element which could become a problem the larger the array. Better way is to use an initializer list.
  int myArray[ ]{ };

• How can you get the size of an array in bytes?
  You can get the size of an array in bytes by using sizeof(array), which will return array length multiplied by an element size.
  array size = array length * element size

• How can you use the function sizeof in order to calculate the number of elements in an array?
  We can calculate the number of elements by dividing the size of the array by the size of an element.
  array length = sizeof(array) / sizeof(array[0])

• What happens when you try to write outside the bounds of the array?
  When you write outside the bounds of the array, the input value will be inserted into memory resulting in undefined behavior.

[Atlas]

What is an array?

Array is an aggregate data type that lets us access many variables of the same type through a single identifier.

Which index would you use to access the 2nd variable in an array?

1. arrayName[1]{}; Because 0 is the first value of an array element.

What can you say about the size of an array?

in C++ arrays’ sizes can be fixed and they are called fixed length arrays, are arrays where the length is known at compile time. like int arrayName[12]{} means the array length is fixed to 12 integers. Or we can determine the length of an array in C++ by assigning the values in an array which length hasn’t been yet given: int arrayName[]{23,454,2623}; //arrayName length is 3

How can you initialize an array?

In various ways,
Entering the values manually:
int arrayName [5]; arrayName[0] = 3; arrayName[1] = 5; arrayName[2] = 16; //...
More convineint way:
int prime[4]{ 76, 24, 12, 99 };
By letting the initializer list sets length of the array:
int array[]{ 43, 12, 77, 26, 93 };

How can you get the size of an array in bytes?

sizeof(array)

How can you use the function sizeof in order to calculate the number of elements in an array?

sizeof(array) / sizeof(array[0])

What happens when you try to write outside the bounds of the array?

This can be considered in Responsibility Memory MAnagement concept via Buffer Overflow Situation issue and the compiler, which actually touching an old / later memory address which potentially has operation codes, let’s say might cause a infinit loop, such exploits and access to root priviliages in a linux machine. Shortly damn valnurable.

Btw, you may have heard about the EOS Vulnerability, it occured due to writing outside of the array bounds (watch here: https://www.youtube.com/watch?v=37H1PJMoN3M).

check. It was horribly interesting.

At the bottom of the article you’ll see a quiz - make sure to do the quiz!

I’ve done it, i was almost there,

1. Declare an array to hold the high temperature (to the nearest tenth of a degree) for each day of a year (assume 365 days in a year). Initialize the array with a value of 0.0 for each day.

double highTemperature[365]{0.0};

I was very close, technically it’s not wrong but the answer is :

double highTemperature[365]{};

Giving nothing as a value to defined array eventually gets registered as 0, so double type of definition brings 0.0 anyway. Correct me if I’m wrong please.

2. Set up an enum with the names of the following animals: chicken, dog, cat, elephant, duck, and snake. Put the enum in a namespace. Define an array with an element for each of these animals, and use an initializer list to initialize each element to hold the number of legs that animal has.
   Write a main function that prints the number of legs an elephant has, using the enumerator.

#include <iostream>
using namespace std;

namespace Animals
{
	enum Animals
	{
		chicken,
		dog,
		cat,
		elephant,
		duck,
		snake,
		max_legs
	};
}


int main() 
{
	int legs[Animals::max_legs]{};
	legs[Animals::elephant] = 4;
	return 0;
}

I was very close, the answer is:

#include <iostream>
 
namespace Animals
{
		enum Animals // The name of this enum could be omitted since it isn't used anywhere
		{
			chicken,
			dog,
			cat,
			elephant,
			duck,
			snake,
			max_animals
		};
}
 
int main()
{
		int legs[Animals::max_animals]{ 2, 4, 4, 4, 2, 0 };
		std::cout << "An elephant has " << legs[Animals::elephant] << " legs.\n";
 
		return 0;
}

[Yuanming]

1. An array is an aggregate data type which allows us to group variables of the sama data type.

2. Index 1

3. The size of an array is determined by array length, which displays how many variables are in the array.

4. Using an initializer list e.g. int prime[5]{ 2, 3, 5, 7, 11 };

5. Using sizeof(array);

6. Using sizeof(arr)/sizeof(int) to determine the number of elements in an array.

7. It will result in undefined behaviour and cause the program to crash due to invalid indices.