stream: play with the STREAM benchmark

userland/c/multidimentional_array.c

@@ -0,0 +1,34 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#c
+ *
+ * Multidimentional arrays are generally a bad idea that confuses
+ * everyone, use single dimentional arrays + indexing if possible.
+ * But here goes nothing.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(void) {
+    /* Initialized in the code. */
+    {
+        /* We can skip the first dimension as it is inferred. */
+        int is[][3] = {
+            {1, 2, 3,},
+            {4, 5, 5,},
+        };
+        assert(is[0][0] == 1);
+        assert(is[0][1] == 2);
+        assert(is[1][0] == 4);
+
+        /* We can get the total sizes of either the entire array,
+         * or of just on row. */
+        assert(sizeof(is) == 6 * sizeof(is[0][0]));
+        assert(sizeof(is[0]) == 3 * sizeof(is[0][0]));
+
+        /* Multi dimentional arrays are contiguous and row major. */
+        assert(&is[0][1] - &is[0][0] == 1);
+        assert(&is[1][0] - &is[0][0] == 3);
+    }
+    return EXIT_SUCCESS;
+}