First commit

001_PalindromeNumber.c

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+// Coding Interviews: Questions, Analysis & Solutions
+// Harry He
+
+#include <stdio.h>
+#include <string.h>
+
+// ==================== Solution 1 ====================
+
+int IsPalindrome(const char* const string)
+{
+    int palindrome = 1;
+    if(string != NULL)
+    {
+        int length = strlen(string);
+        int half = length >> 1;
+
+        int i;
+        for(i = 0; i < half; ++ i)
+        {
+            if(string[i] != string[length - 1 - i])
+            {
+                palindrome = 0;
+                break;
+            }
+        }
+    }
+
+    return palindrome;
+}
+
+/* It returns 1 when number is palindrome, otherwise returns 0. */
+#define NUMBER_LENGTH 20
+int IsPalindrome_solution1(unsigned int number)
+{
+    char string[NUMBER_LENGTH];
+    sprintf(string, "%d", number);
+
+    return IsPalindrome(string);
+}
+
+// ==================== Solution 2 ====================
+
+/* It returns 1 when number is palindrome, otherwise returns 0. */
+int IsPalindrome_solution2(unsigned int number)
+{
+    int reversed = 0;
+    int copy = number;
+
+    while(number != 0)
+    {
+        reversed = reversed * 10 + number % 10;
+        number /= 10;
+    }
+
+    return (reversed == copy) ? 1 : 0;
+}
+
+// ==================== Test Code ====================
+
+void Test(char* testName, int number, int expected)
+{
+    if(testName != NULL)
+        printf("%s begins: ", testName);
+
+    if(IsPalindrome_solution1(number) == expected)
+        printf("solution 1 passed; ");
+    else
+        printf("solution 1 FAILED; ");
+
+    if(IsPalindrome_solution2(number) == expected)
+        printf("solution 2 passed.\n");
+    else
+        printf("solution 2 FAILED.\n");
+}
+
+int main(int argc, char* argv[])
+{
+    Test("Test1", 5, 1);
+    Test("Test2", 33, 1);
+    Test("Test3", 242, 1);
+    Test("Test4", 2332, 1);
+
+    Test("Test5", 0, 1);
+
+    Test("Test6", 32, 0);
+    Test("Test7", 233, 0);
+    Test("Test8", 2331, 0);
+    Test("Test9", 2322, 0);
+
+	return 0;
+}

002_AssignmentOperator.cpp

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+// Coding Interviews: Questions, Analysis & Solutions
+// Harry He
+
+#include <stdio.h>
+#include <string>
+
+class CMyString
+{
+public:
+    CMyString(char* pData = NULL);
+    CMyString(const CMyString& str);
+    ~CMyString(void);
+
+    CMyString& operator = (const CMyString& str);
+
+    void Print();
+
+private:
+    char* m_pData;
+};
+
+CMyString::CMyString(char *pData)
+{
+    if(pData == NULL)
+    {
+        m_pData = new char[1];
+        m_pData[0] = '\0';
+    }
+    else
+    {
+        int length = strlen(pData);
+        m_pData = new char[length + 1];
+        strcpy(m_pData, pData);
+    }
+}
+
+CMyString::CMyString(const CMyString &str)
+{
+    int length = strlen(str.m_pData);
+    m_pData = new char[length + 1];
+    strcpy(m_pData, str.m_pData);
+}
+
+CMyString::~CMyString()
+{
+    delete[] m_pData;
+}
+
+CMyString& CMyString::operator = (const CMyString& str)
+{
+    if(this == &str)
+        return *this;
+
+    delete []m_pData;
+    m_pData = NULL;
+
+    m_pData = new char[strlen(str.m_pData) + 1];
+    strcpy(m_pData, str.m_pData);
+
+    return *this;
+}
+
+// ==================== Test Code ====================
+
+void CMyString::Print()
+{
+    printf("%s", m_pData);
+}
+
+void Test1()
+{
+    printf("Test1 begins:\n");
+
+    char* text = "Hello world";
+
+    CMyString str1(text);
+    CMyString str2;
+    str2 = str1;
+
+    printf("The expected result is: %s.\n", text);
+
+    printf("The actual result is: ");
+    str2.Print();
+    printf(".\n\n");
+}
+
+// Assign to self
+void Test2()
+{
+    printf("Test2 begins:\n");
+
+    char* text = "Hello world";
+
+    CMyString str1(text);
+    str1 = str1;
+
+    printf("The expected result is: %s.\n", text);
+
+    printf("The actual result is: ");
+    str1.Print();
+    printf(".\n\n");
+}
+
+// Continuous Assignments
+void Test3()
+{
+    printf("Test3 begins:\n");
+
+    char* text = "Hello world";
+
+    CMyString str1(text);
+    CMyString str2, str3;
+    str3 = str2 = str1;
+
+    printf("The expected result is: %s.\n", text);
+
+    printf("The actual result is: ");
+    str2.Print();
+    printf(".\n");
+
+    printf("The expected result is: %s.\n", text);
+
+    printf("The actual result is: ");
+    str3.Print();
+    printf(".\n\n");
+}
+
+int main(int argc, char* argv[])
+{
+    Test1();
+    Test2();
+    Test3();
+
+    return 0;
+}

003_Singleton.cs

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+// Coding Interviews: Questions, Analysis & Solutions
+// Harry He
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace _003_Singleton
+{
+    public sealed class Singleton1
+    {
+        private Singleton1()
+        {
+        }
+
+        private static Singleton1 instance = null;
+        public static Singleton1 Instance
+        {
+            get
+            {
+                if (instance == null)
+                    instance = new Singleton1();
+
+                return instance;
+            }
+        }
+    }
+
+    public sealed class Singleton2
+    {
+        private Singleton2()
+        {
+        }
+
+        private static readonly object syncObj = new object();
+
+        private static Singleton2 instance = null;
+        public static Singleton2 Instance
+        {
+            get
+            {
+                lock (syncObj)
+                {
+                    if (instance == null)
+                        instance = new Singleton2();
+                }
+
+                return instance;
+            }
+        }
+    }
+
+    public sealed class Singleton3
+    {
+        private Singleton3()
+        {
+        }
+
+        private static object syncObj = new object();
+
+        private static Singleton3 instance = null;
+        public static Singleton3 Instance
+        {
+            get
+            {
+                if (instance == null)
+                {
+                    lock (syncObj)
+                    {
+                        if (instance == null)
+                            instance = new Singleton3();
+                    }
+                }
+
+                return instance;
+            }
+        }
+    }
+
+    public sealed class Singleton4
+    {
+        private Singleton4()
+        {
+            Console.WriteLine("An instance of Singleton4 is created");
+        }
+
+        public static void Print()
+        {
+            Console.WriteLine("Singleton4 Print");
+        }
+
+        private static Singleton4 instance = new Singleton4();
+        public static Singleton4 Instance
+        {
+            get
+            {
+                return instance;
+            }
+        }
+    }
+
+    public sealed class Singleton5
+    {
+        Singleton5()
+        {
+            Console.WriteLine("An instance of Singleton5 is created");
+        }
+
+        public static void Print()
+        {
+            Console.WriteLine("Singleton5 Print");
+        }
+
+        public static Singleton5 Instance
+        {
+            get
+            {
+                return Nested.instance;
+            }
+        }
+
+        class Nested
+        {
+            static Nested()
+            {
+            }
+
+            internal static readonly Singleton5 instance = new Singleton5();
+        }
+    }
+
+    class Program
+    {
+        static void Main(string[] args)
+        {
+            Singleton4.Print();
+            Singleton5.Print();
+        }
+    }
+}