Left off on 2.5 Arithmetic Operators

ch_02/arithmetic_operations-leap_year/main.c

@@ -0,0 +1,95 @@
+/*
+ *
+ * Demonstrating the use of arithmetic operators
+ *
+ * Author: Kun Deng
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+
+// Parameter target_type is the valid target type
+// Should match the symbolic constants of HEX or NUMBER
+//
+// Return values
+// 0 - Invalid
+// 1 - Valid
+int is_valid_source(char *value);
+
+
+// Checks to see if the provided year is a leap year.
+// Returns 1 if true and 0 if not
+int is_leap_year(const int year);
+
+
+int main(int argc, char **argv)
+{
+    if (argc != 2)
+    {
+        printf("Provide a year as an argument\n");
+        printf("./program.out 2000\n");
+
+        return -1;
+    }
+
+    if (is_valid_source(argv[1]) != 1)
+    {
+        printf("%s is not a number\n", argv[1]);
+
+        return -1;
+    }
+
+    const int year_value = atoi(argv[1]);
+
+    if (is_leap_year(year_value) == 1)
+    {
+        printf("%d is a leap year\n", year_value);
+    }
+    else
+    {
+        printf("%d is not a leap year\n", year_value);
+    }
+
+    return 0;
+}
+
+
+int is_valid_source(char *value)
+{
+    int result = 1;
+
+    for (int i = 0; value[i] != '\0'; ++i)
+    {
+        char val = value[i];
+
+        // ASCII values 48 - 57 are numbers
+        // Checks to see if there are non-numbers
+        if (val <= 47 || val >= 58)
+        {
+            result = 0;
+            break;
+        }
+    }
+
+    return result;
+}
+
+int is_leap_year(const int year)
+{
+    int result;
+    int aa = year % 4;
+    int ab = year % 100;
+    int b = year % 400;
+
+    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
+    {
+        result = 1;
+    }
+    else
+    {
+        result = 0;
+    }
+
+    return result;
+}

ch_02/declarations/main.c

@@ -0,0 +1,42 @@
+/*
+ *
+ * This program is an example of declarations
+ *
+ * Author: Kun Deng
+ */
+
+
+#include <stdio.h>
+
+// The const in the parameter field ensures that the variable value cannot be modified
+// within the function
+void faux_change(const int value);
+
+int main()
+{
+    // Single variable declarations
+    int s_low;
+    int s_high;
+    int s_mid;
+
+    // Multi-variable declarations
+    int m_low, m_high, m_mid;
+
+
+    // Declaring and initializing variables
+    char a = 'a';
+    int k = 5;
+
+    printf("k is %d before calling faux_change()\n", k);
+    faux_change(k);
+    printf("After: %d\n", k);
+
+    return 0;
+}
+
+
+void faux_change(const int value)
+{
+    // If uncommented, will not compile
+    // value = value * 2;
+}