Summary - Arrays
- C++ course
- Beginner
- Lesson 58/116
- 5 min
Use C-style and std::array to write a grade table.
Summary - Arrays
In this group you learned ways to hold fixed-size data in C++: C-style arrays, std::array, multidimensional arrays and iterating with loops. Each has its own advantage and use case.
Now you have two tasks. First you will sum three grades with a C-style array, then print four numbers with std::array using range-based for. Such accumulation and loop tasks appear all the time in real programs, for example in grade averages, temperature readings or stock counts.
Practice Grade table (C-style)
The grades array is set to {85, 90, 78}. Use a for (int i = 0; i < 3; i++) loop to accumulate with sum += grades[i] and print it with std::cout << sum. The output must be 253.
Starter code
#include <iostream>
int main() {
int grades[3] = {85, 90, 78};
int sum = 0;
// Compute and print the sum
return 0;
}Sample solution
#include <iostream>
int main() {
int grades[3] = {85, 90, 78};
int sum = 0;
for (int i = 0; i < 3; i++) {
sum += grades[i];
}
std::cout << sum << std::endl;
return 0;
}Expected output
253
Practice Print with std::array
The std::array<int, 4> nums = {2, 4, 6, 8}; is given. Use a for (int x : nums) loop to print each element with std::cout << x; on a single line. The output must be 2468.
Starter code
#include <iostream>
#include <array>
int main() {
std::array<int, 4> nums = {2, 4, 6, 8};
// Print with range-based for
return 0;
}Sample solution
#include <iostream>
#include <array>
int main() {
std::array<int, 4> nums = {2, 4, 6, 8};
for (int x : nums) {
std::cout << x;
}
std::cout << std::endl;
return 0;
}Expected output
2468
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does std::array<int, 5> a; a.size() return?
std::array<int, 5> a;
a.size()- 3
- 0
- 5 Correct answer
- Unclear
Explanation: The size template parameter is 5; size() returns 5.
2 Match each array type to its scenario
| Term | Meaning |
|---|---|
int nums[5] |
C-style array |
std::array<int, 5> |
Modern array |
int matrix[2][3] |
Multidimensional |
nums[i] |
Array access |
3 Write the C-style array declaration
int ____[4] = {2, 4, 6, 8};int nums[4] = {2, 4, 6, 8};Explanation: The array name is nums; plural naming fits arrays.