Lab 2

lab02/.gitignore

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+.*.swp
+*.o
+test_leap
+*.creator*
+*.cflags
+*.config
+*.cxxflags
+*.files
+*.includes
+.vscode/

lab02/README.md

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+# CITS3007 lab 2 demo repository
+
+This repository contains a Makefile and C code for two programs,
+"factorial" and "segfault".
+
+## Building
+
+Build with `make`.
+

lab02/factorial.c

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+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+
+// contains INT_MAX
+#include <limits.h>
+
+/* return the factorial of n.
+ * The result is undefined if n < 0.
+ *
+ * The largest factorial that can be calculated depends
+ * on your platform. On platforms where a `long`
+ * is 8 bytes, the results of the function for
+ * any n greater than 20 are undefined.
+ */
+long factorial(int n) {
+  long result = 1;
+  for (int i = n; i > 0; i--) {
+    result = result * i;
+  }
+  return result;
+}
+
+int main(int argc, char **argv) {
+  argc--;
+  argv++;
+
+  if (argc != 1) {
+    fprintf(stderr, "Error: expected 1 command-line argument (an INT), but got %d\n", argc);
+    exit(1);
+  }
+
+  char *end;
+
+  // clear errno so we can check whether strtol fails
+  errno = 0;
+  long n = strtol(argv[0], &end, 10);
+  int res_errno = errno;
+
+  if (end == argv[0]) {
+    fprintf(stderr, "Error: couldn't interpret '%s' as a number\n", argv[0]);
+    exit(1);
+  } else if (res_errno == ERANGE) {
+    fprintf(stderr, "Error: '%s' is outside the range of numbers we can handle\n", argv[0]);
+    exit(1);
+  } else if (n > INT_MAX) {
+    fprintf(stderr, "Error: '%s' is too big to fit in an int\n", argv[0]);
+    exit(1);
+  } else if (n < 0) {
+    fprintf(stderr, "Error: invalid value %ld:"
+            "factorial can only be calculated for non-negative numbers\n", n);
+    exit(1);
+  }
+
+  int nn = (short) n;
+  long result = factorial(nn);
+  printf("factorial(%d) is %ld\n", nn, result);
+}

lab02/segfault.c

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+
+#include <stdlib.h>
+#include <stdio.h>
+
+#define STR_BUF_SIZE 1024
+
+#define STR_HELPER(x) #x
+#define STR(x) STR_HELPER(x)
+#define CHECK_ALLOC(block)                                   \
+  if (block == 0)                                            \
+  {                                                          \
+    printf("malloc() failed at " STR(__LINE__) ". Exited."); \
+    exit(-1);                                                \
+  }
+
+int main(void)
+{
+  char *buf;
+  buf = malloc(STR_BUF_SIZE); // allocate a large buffer
+  CHECK_ALLOC(buf)
+
+  printf("type some text and hit 'return':\n");
+  fgets(buf, STR_BUF_SIZE, stdin); // read 1024 chars into buf
+  printf("\n%s\n\n", buf);         // print what was entered
+  free(buf);
+  return 0;
+}