Why does the `==` operator not work for comparing C arrays?

Understanding Array Equality Comparison in C

Arrays are a fundamental data structure in C , but their equality comparison using the == operator often leads to unexpected results. This article aims to clarify why this occurs and provide alternatives for performing element-wise array comparisons.

Problem:

Consider the following code snippet:

int main() {
    int iar1[] = {1, 2, 3, 4, 5};
    int iar2[] = {1, 2, 3, 4, 5};

    if (iar1 == iar2)
        cout <p>Why does the output from this code indicate that the arrays are not equal?</p><p><strong>Answer:</strong></p><p>The equality operator == does not perform element-wise comparison for arrays. Instead, it compares the addresses of the arrays, which are always different because they are stored in distinct memory locations.</p><p>To understand why, we need to consider the concept of "decay." In C  , arrays decay to pointers to their first elements when they are used in an expression. Therefore, the statement:</p><pre class="brush:php;toolbar:false">if (iar1 == iar2)

is equivalent to:

if (&iar1[0] == &iar2[0])

Since &iar1[0] and &iar2[0] represent different memory locations, the comparison evaluates to false.

Alternatives for Element-Wise Array Comparison:

Instead of comparing arrays with the == operator, there are two recommended approaches:

1. Using a Loop:

To perform element-wise comparison, you can iterate over the arrays and check each element individually:

bool areEqual = true;
for (int i = 0; i <ol start="2"><li><strong>Using std::array:</strong></li></ol><p>The C   Standard Library provides the std::array type, which allows for element-wise comparison using the == operator:</p><pre class="brush:php;toolbar:false">std::array<int> iar1 {1, 2, 3, 4, 5};
std::array<int> iar2 {1, 2, 3, 4, 5};

if (iar1 == iar2) {
    cout </int></int>

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