c/ex1.c

@@ -1,26 +0,0 @@
-#include <stdbool.h>
-#include <stddef.h>
-
-struct node_t {
-    unsigned v;
-    struct node_t* next;
-};
-
-struct node_t* even_nodes(struct node_t** list) {
-    struct node_t* res = NULL;
-
-    while (true) {
-        struct node_t* next = (*list)->next;
-
-        if ((*list)->v % 2 == 0) {
-            // Pop element from the list, add it to head of the other
-            (*list)->next = res;
-            res = *list;
-        }
-
-        *list = next;
-    }
-
-    // NOTE: this is in reverse order from the input list
-    return res;
-}

c/ex2.c

@@ -1,30 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-
-char* f(int m) {
-    char buf[6];
-    int x;
-
-    if (m == 1 && x-- /* variable is read before initialization */) {
-        strcpy(buf, "AAAAAA"); // null-byte copy overflows buffer at index 7
-        return buf;            // Return stack allocated array
-    } else if (m == 2) {
-        char* msg = (char*)malloc(100); // malloc is declared in <stdlib.h>
-        // While technically not UB, as it will be implicitly declared by the
-        // compiler, this is error-prone and the implicit declaration most
-        // likely does not match the actual function
-        strcpy(msg, "BBBBBB");
-        return msg;
-    }
-    // Missing return value
-}
-
-int main(int argc, char** argv) {
-    char* m;
-    m = f(argc);
-    putchar(m[0]); // if m != 2, either reads garbage stack memory or
-                   // non-sensical pointer due to missing return value
-    return 0;
-    // Potential memory leak, if m == 2
-    // While not UB, it is frowned upon
-}

c/ex3.c

@@ -1,32 +0,0 @@
-#include <limits.h>
-#include <stddef.h>
-
-static unsigned char reverse_byte(unsigned char c) {
-    unsigned char res = 0;
-    for (size_t i = 0; i < CHAR_BIT; ++i) {
-        unsigned char bit = (c & (1 << i));
-        res |= bit << (CHAR_BIT - i - 1);
-    }
-    return res;
-}
-
-static void swap_bytes(unsigned char* lhs, unsigned char* rhs) {
-    unsigned char tmp = *lhs;
-    *lhs = *rhs;
-    *rhs = tmp;
-}
-
-void reverse_bytes(unsigned char* buf, size_t n) {
-    if (!buf || !n)
-        return;
-
-    // No need to worry about applying reverse_byte twice in the middle by
-    // mistake if done in a preliminary pass
-    for (size_t i = 0; i < n; ++i) {
-        buf[i] = reverse_byte(buf[i]);
-    }
-
-    for (size_t i = 0; i <= (n / 2); ++i) {
-        swap_bytes(&buf[i], &buf[n - 1 - i]);
-    }
-}

cpp/ex1.cc

@@ -1,28 +0,0 @@
-#ifdef USE_ATOMIC_N
-#include <atomic>
-#endif
-
-class CountInstances {
-public:
-    CountInstances() {
-        ++n_instances_;
-    }
-
-    ~CountInstances() {
-        --n_instances_;
-    }
-
-    int nobjs() const {
-        return n_instances_; // If using atomics, load could use a more relaxed
-                             // memory order, such as memory_order_acquire
-    }
-
-private:
-#ifdef USE_ATOMIC_N
-    // Can be used in a multi-thread program
-    static atomic<int> n_instances_;
-#else
-    // Using a bare int mean races if used in a multi-threaded context
-    static int n_instances_;
-#endif
-};

cpp/ex2.cc

@@ -1 +0,0 @@
-../c/ex1.c