How to compare two float arrays for exact equality in C

1 Answer

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/*
    Compare two float arrays element-by-element for exact equality.
    Floating‑point values must match bit-for-bit; even tiny rounding
    differences will cause inequality. This is stricter than using
    a tolerance-based comparison.
*/

#include <stdio.h>
#include <stdbool.h>

/* 
   Compares two float arrays and returns true only if all elements
   are exactly equal. This uses direct == comparison, which checks
   for exact binary equality.
*/
bool compareFloatArraysExact(const float *a, const float *b, size_t length) {

    // If length is zero, treat arrays as equal
    if (length == 0) {
        return true;
    }

    // Compare each element directly
    for (size_t i = 0; i < length; i++) {
        if (a[i] != b[i]) {
            return false;   // Found mismatch → arrays differ
        }
    }

    // All elements matched exactly
    return true;
}

/*
   Prints the comparison result.
*/
void printComparison(bool result) {
    if (result) {
        printf("Arrays are exactly equal.\n");
    } else {
        printf("Arrays differ.\n");
    }
}

int main(void) {

    // Example arrays
    float floatArr1[] = {
        12314.9872f,
        3.14f,
        12387.91834f,
        8873.579013f
    };

    float floatArr2[] = {
        12314.9872f,
        3.14f,
        12387.91834f,
        8873.579013f
    };

    // Determine array length
    size_t length = sizeof(floatArr1) / sizeof(floatArr1[0]);

    // Perform exact comparison
    bool result = compareFloatArraysExact(floatArr1, floatArr2, length);

    // Output result
    printComparison(result);

    return 0;
}



/*
run:

Arrays are exactly equal.

*/

 



answered Sep 9 by avibootz
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