Add example for local and global variables

c_modern_approach/ProgramOrganization/global_variables.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define MAX_NUMBER 100
+
+/* External variable */
+int secret_number;
+
+// Prototypes
+void initialize_number_generator(void);
+void choose_new_secret_number(void);
+void read_guess(void);
+
+int main() {
+  char command = 'y';
+  printf("Guess the secret number between 1 and %d. \n\n", MAX_NUMBER);
+  initialize_number_generator();
+  do {
+    choose_new_secret_number();
+    printf("New number has been chosen.\n");
+    read_guess();
+    printf("Play again? (Y/N)\n");
+    while (getchar() != '\n')
+      ; // Discard any leftover input
+    scanf("%c", &command);
+    printf("\n");
+  } while (command == 'y' || command == 'Y');
+  exit(0);
+}
+
+/**
+ * @brief Initializing random number generator based on current time
+ * time(NULL) returns current time in `time_t` format
+ */
+void initialize_number_generator(void) { srand((unsigned)time(NULL)); }
+
+/**
+ * @brief Here we are using rand() function and getting the remaining value of
+ * deletion by MAX_NUMBER + 1 to get random value between 0 and 100
+ */
+void choose_new_secret_number(void) {
+  secret_number = rand() % MAX_NUMBER + 1;
+};
+
+void read_guess(void) {
+  int guess, num_guesses = 0;
+  for (;;) {
+    num_guesses++;
+    printf("Enter guess: ");
+    scanf("%d", &guess);
+    if (guess == secret_number) {
+      printf("You guessed the number after %d attempts!\n\n", num_guesses);
+      return;
+    } else if (guess < secret_number) {
+      printf("Missed! Secret value is lower than your value\n");
+    } else {
+      printf("Missed! Secret value is higher than your value\n");
+    }
+  }
+};

c_modern_approach/ProgramOrganization/static_local_variables.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+#include <stdlib.h>
+/**
+ * @brief Function for demonstration static local variables
+ */
+void test_static() {
+  static int static_var;
+  static_var += 1;
+  printf("%d\n", static_var);
+}
+
+int main() {
+  test_static();
+  test_static();
+  test_static();
+  test_static();
+  exit(0);
+}