[SPCA] Start pointers

semester3/spca/code-examples/00_c/00_basics/05_pointers.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main( int argc, char *argv[] ) {
+    int x = 0;
+    int *p = &x;          // Get x's memory address
+    printf( "%p\n", p );  // Print the address of x
+    printf( "%d\n", *p ); // Dereference pointer (get contents of memory location)
+    *p = 10;              // Dereference assign
+    int **dbl_p = &p;     // Double pointer (pointer to pointer to value)
+    int *null_p = NULL;   // Create NULL pointer
+    *null_p = 1;          // Segmentation fault due to null pointer dereference
+
+    // ── pointer arithmetic ───────────────────────────────────────────
+    // Already seen a bit in the c arrays section
+    int arr[ 3 ] = { 2, 3, 4 };
+    char c_arr[ 3 ] = { 'A', 'B', 'C' };
+    int *arr_p = &arr[ 1 ];
+    char *c_arr_p = &c_arr[ 1 ];
+    c_arr_p += 1; // Now points to c_arr[2]
+    arr_p -= 1;   // Now points to arr[0]
+
+    char *arr_p_c = (char *) arr_p; // Cast to char pointer (points to first byte of arr[0])
+    printf( "%d", *( arr_p - 5 ) ); // No boundary checks (can access any memory)
+
+    return EXIT_SUCCESS;
+}