upload 4.30, happy holiday

13/myPow.c

@@ -8,13 +8,13 @@ double myPow(double x, long  n)
   {
     return 1;
   }
-  else;
+
   if (n < 0)
   {
     n = -n;
     x = 1 / x;
   }
-  else;
+
   while (n != 1)
   {
     if (n % 2 == 1)

13/myPow.h

@@ -1,2 +1,29 @@
-double myPow(double x, long  n);
+double myPow(double x, long  n)
+{
+  double y = 1;
+
+  if (x == 1 || n == 0)
+  {
+    return 1;
+  }
+
+  if (n < 0)
+  {
+    n = -n;
+    x = 1 / x;
+  }
+
+  while (n != 1)
+  {
+    if (n % 2 == 1)
+    {
+      y *= x;
+    }
+    else;
+    x *= x;
+    n /= 2;
+  }
+
+  return y * x;
+}
 

14/14.1.c

@@ -1,5 +1,5 @@
 //加强版;
-#include "s_gets.h"
+#include "../s_gets.h"
 #define MAXTITL 30
 #define MAXBK 100
 //声明结构;

14/14.14.c

@@ -1,4 +1,4 @@
-#include "s_gets.h"
+#include "../s_gets.h"
 #define MAXTITL 40
 #define MAXAUTL 40
 #define MAXBKS 10
@@ -63,7 +63,7 @@ int main (void)
     puts ("Here is the list of your books: ");
     for (index = 0; index < count; index ++)
     {
-      printf ("%s by %s: $%.2f \n", library[count].title, library[count].author, library[count].value);
+      printf ("%s by %s: $%.2f \n", library[index].title, library[index].author, library[index].value);
     }
     fwrite (&library[filecount], size, count - filecount, pbooks);
   }else

14/14.15.c

@@ -0,0 +1,88 @@
+#include <stdio.h>
+
+//这个结构有点好玩, 可录入的值为定义的几个值之一, 并且每录入一个新值就会洗掉先前录入的值;
+union hold
+{
+  int digit;
+  double bigfl;
+  char letter;
+};
+
+int main (void)
+{
+  union hold save[10];   //一个内含十个hold类型的数组;
+  union hold * pu;   //一个指向hold类型的指针;
+  union hold valA;   //一个hold类型的union变量;
+  int x;
+
+  valA.letter = 'A';
+  union hold valB = valA;   //使用另一个联合初始化联合;
+  union hold valC = {88};   //初始化联合中的某个成员;
+  union hold valD = {.bigfl = 118.2};   //指定初始化器;
+
+  valA.digit = 23;   //把23存储在valA, 占用2字节;
+  valA.bigfl = 2.0;   //清除23并把2.0存储在valA, 占用8字节;
+  valA.letter = 'h';   //清除2.0并把'h'存储在valA, 占用1字节;
+
+  pu = &valA;
+  x = pu -> digit;   //相当于x = valA.digit;
+
+  /*
+  x = (pu -> letter) * 3.02   这种写法是错误的;
+  */
+
+  //以下是一段车辆管理代码;
+  struct owner   //车主信息;
+  {
+    char socsecurity[12];
+    //代码;
+  };
+  struct leasecompany   //租赁者信息;
+  {
+    char name[40];
+    char headquarters[40];
+    //代码;
+  };
+
+  union data   //存储信息的联合;
+  {
+    struct owner owncar;
+    struct leasecompany leasecar;
+  };
+
+  struct car_data
+  {
+    char make[15];
+    int status;   //status为判断值, 当status为0时写车主信息入*结构变量名*.ownerinfo.owncar.socsecurity,
+                  //当status为1时则写租赁者信息;
+    union data ownerinfo;
+    //代码;
+  };
+
+  //用匿名联合重写以上代码;
+  struct owner1   //车主信息;
+  {
+    char socsecurity[12];
+    //代码;
+  };
+  struct leasecompany1   //租赁者信息;
+  {
+    char name[40];
+    char headquarters[40];
+    //代码;
+  };
+  struct car_data1
+  {
+    char make[15];
+    int status;   //status为判断值, 当status为0时写车主信息入*结构变量名*.owncar.socsecurity,
+                  //当status为1时则写租赁者信息;
+    union
+    {
+      struct owner1 owncar;
+      struct leasecompany1 leasecar;
+    };
+    //代码;
+  };
+
+  return 0;
+}

14/14.16.c

@@ -0,0 +1,15 @@
+#include <stdio.h>
+
+int main (void)
+{
+  enum spectrum   //green = 302, blue = 303 ... ;
+  {
+    red = 100, orange = 300, yellow = 301, green, blue, violet, purple
+  } color;
+
+  for (color = blue; color != yellow; (color < yellow) ? color ++ : color --);
+
+  printf ("%u   %u   %u", color, red, purple);
+
+  return 0;
+}

14/14.17.c

@@ -0,0 +1,69 @@
+#include "../s_gets.h"
+#define LEN 30
+
+enum spectrum
+{
+  red, orange, yellow, green, blue, violet, purple
+};
+
+const char * colors[] = {
+    "red", "orange", "yellow", "green", "blue", "violet", "purple"
+};
+
+int main (void)
+{
+  char choice[LEN];
+  enum spectrum color;
+  bool color_is_found = false;
+
+  puts ("Enter a color (empty line to quit): ");
+
+  while ((s_gets(choice, LEN)) && (choice[0]))
+  {
+    for (color = red; color <= purple; color ++)
+    {
+      if (!(strcmp (choice, colors[color])))
+      {
+        color_is_found = true;
+        break;
+      }
+    }
+
+    if (color_is_found)
+    {
+      switch (color)
+      {
+        case red:
+          puts ("Rose are red. ");
+          break;
+        case orange:
+          puts ("Poppies are orange. ");
+          break;
+        case yellow:
+          puts ("Sunflowers are yellow. ");
+          break;
+        case green:
+          puts ("Grass is green. ");
+          break;
+        case blue:
+          puts ("Bluebells are blue. ");
+          break;
+        case violet:
+          puts ("Violets are violet. ");
+          break;
+        case purple:
+          puts ("Lavenders are purple. ");
+          break;
+      }
+    }else
+    {
+      printf ("I don't know about %s. \n", choice);
+    }
+
+    color_is_found = false;
+    puts ("Please enter Next color: ");
+  }
+  puts ("Thank you for using. ");
+
+  return 0;
+}

14/14.18.c

@@ -0,0 +1,79 @@
+#include <stdio.h>
+#define ASD struct c \
+{                    \
+  int a;             \
+  int b;             \
+}
+#define STRING1 char *
+
+typedef int arr5[5];
+typedef arr5 * p_arr5;
+typedef p_arr5 arrp10[10];
+
+typedef char (* FRPTC (void)) [5];
+typedef unsigned char BYTE;
+typedef char * STRING;
+typedef struct complex
+{
+  float real;
+  float imag;
+}COMPLEX;
+
+
+int main (void)
+{
+  ASD s;
+  struct c asd;
+  BYTE x, y[10], * z;
+  STRING name, sign;  //等价于 char * name, * sign;
+  STRING1 name1, sign1;   //等价于 char * name, sign; 注意只有name是指针;
+  COMPLEX com = {
+      3.0, 6.0
+  };
+  int board[8][8];
+  int ** ptrr;
+  int * risks[10];   //一个10元素数组, 每个元素为一个(指向int元素的指针);
+  int (* rusks)[10];  //一个指向包含10个(int元素)的数组的指针;
+  int * oof[3][4];   //一个3 * 4元素数组, 每个元素为一个(指向int元素的指针);
+  int (* uuf)[3][4];   //一个指向包含3 * 4个(int元素)的数组的指针;
+  int (* uof[3])[4];   //一个3元素数组, 每个元素为一个(指向包含4个(int元素)的数组)的指针;
+  char fup (int k);
+  char * fump (int k);   //返回(char指针)的函数;
+  char (* frump) (int k);   //指向(返回类型为char的函数)的指针;
+  char (* flump[3]) (int k);   //一个3元素数组, 每个元素为一个指向(返回类型为char的函数)的指针;
+  frump = &fup;
+  for (int n = 0; n < 3; flump[n] = frump, n ++);
+
+  s.b = 1;
+  asd.a = 2;
+  printf ("%s \n", fump (0));
+
+  arr5 togs;   //含有5个(int元素)的数组;
+  p_arr5 p2;   //一个指向(含有5个(int元素)的数组)的指针;
+  arrp10 ap;   //一个内含10个(指向(含有5个(int元素)的数组)的指针)的数组;
+
+  int (* pf)(const char *, ...);   //一个指向函数的指针;
+  pf = printf;   //指的是printf;
+
+  (*pf)("HELLO PRINTF! \n");   //调用;
+  pf ("HELLO PRINTF! \n");   //第二种调用;
+
+  function1 (sqrt);   //传递地址;
+  function2 (sqrt (4.0));   //传递返回值;
+
+  return 0;
+}
+char * fump (int k)
+{
+  if (k)
+  {
+    return ("sdcs");
+  }else
+  {
+    return ("etwt");
+  }
+}
+char fup (int k)
+{
+  return 'm';
+}