Common array operations in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the syntax to declare an array of 5 integers in C++?

You declare it like this: int arr[5]; This creates an array named arr that can hold 5 integers.

beginner

How do you access the third element of an array named arr?

You use the index 2 because counting starts at 0. So, arr[2] gives you the third element.

intermediate

How can you find the size of a statically declared array arr in C++?

Use sizeof(arr) / sizeof(arr[0]). This divides the total bytes of the array by the bytes of one element to get the number of elements.

intermediate

What is the difference between arr[i] and *(arr + i)?

Both access the element at index i. arr[i] is array indexing syntax, while *(arr + i) uses pointer arithmetic. They are equivalent.

intermediate

How do you copy elements from one array to another in C++?

You can use a loop to copy each element one by one, like:<br>for(int i = 0; i < size; i++) { dest[i] = src[i]; }<br>Or use std::copy from the <algorithm> header.

What is the index of the first element in a C++ array?

A 0

B 1

C -1

D Depends on the array size

In C++, array indexing starts at 0, so the first element is at index 0.

Which expression correctly gives the number of elements in a statically declared array arr?

A sizeof(arr)

B sizeof(arr) / sizeof(arr[0])

C sizeof(arr) * sizeof(arr[0])

D sizeof(arr[0]) / sizeof(arr)

Dividing the total size of the array by the size of one element gives the number of elements.

What does arr[3] mean in C++?

A The fourth element of the array

B The third element of the array

C The element at index 2

D An invalid syntax

Indexing starts at 0, so arr[3] is the fourth element.

Which of the following copies elements from one array to another correctly?

A copy(dest, src);

B dest = src;

C dest.copy(src);

D for(int i=0; i&lt;size; i++) dest[i] = src[i];

Arrays cannot be assigned directly; you must copy elements one by one or use std::copy.

What is the result of *(arr + 2)?

A The second element of the array

B The first element of the array

C The third element of the array

D A pointer to the array

Pointer arithmetic moves the pointer by 2 elements, so dereferencing gives the third element.

Explain how to declare, access, and find the size of a static array in C++.

Think about how memory size relates to element count.

Describe two ways to copy elements from one array to another in C++.

Remember arrays cannot be assigned directly.