Summary  
This chapter covers accessing elements in an array by their zero-based index.  

General domain of usage  
Data processing

### Reminder how to access an array by index



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> Note
>
> Index **counting starts from zero**, making the first element in a list or array the **zeroth** element.

#define CATCH_CONFIG_MAIN
#include <catch2/catch.hpp>

double calculateAverage(int grades[]);

TEST_CASE("Average for {80, 90, 75, 95} should be 85", "[calculateAverage]") {
    int grades[4] = {80, 90, 75, 95};
    double result = calculateAverage(grades);
    REQUIRE(result == Approx(85.0)); // For the input array {80, 90, 75, 95}, the result should be 85
}

TEST_CASE("Average for {100, 100, 100, 100} should be 100", "[calculateAverage]") {
    int grades[4] = {100, 100, 100, 100};
    double result = calculateAverage(grades);
    REQUIRE(result == Approx(100.0)); // For the input array {100, 100, 100, 100}, the result should be 100
}

TEST_CASE("Average for {0, 0, 0, 0} should be 0", "[calculateAverage]") {
    int grades[4] = {0, 0, 0, 0};
    double result = calculateAverage(grades);
    REQUIRE(result == Approx(0.0)); // For the input array {0, 0, 0, 0}, the result should be 0
}

TEST_CASE("Average for {70, 80, 75, 76} should be 75.25", "[calculateAverage]") {
    int grades[4] = {70, 80, 75, 76};
    double result = calculateAverage(grades);
    REQUIRE(result == Approx(75.25)); // For the input array {70, 80, 75, 76}, the result should be 75.25
}


test.cpp

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Challenge: Working with the Array

Reminder how to access an array by index

Example

Solution