daily update 5.15

14/14.18.c

@@ -1,3 +1,5 @@
+//函数指针使用方式;
+
 #include <stdio.h>
 #define ASD struct c \
 {                    \

15/15.9_10.h

@@ -1,4 +1,4 @@
-#include "../s_gets.h"
+#include "../s_gets1.h"
 #include <limits.h>
 
 int b2dcov (const char * pbin)

16/16.1.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+int main (void)
+{
+  int/**/fh/**/;
+
+  fh = 7;
+  printf ("%d\n", fh);
+
+  return/**/0;
+}

16/16.10.c

@@ -0,0 +1,18 @@
+#if __STDC_VERSION__ != 201112L
+#error Not C11
+
+#endif
+#include <stdio.h>
+
+#line 10 "egvev.c"
+
+int main (void)
+{
+  printf ("This is line %d. \n", __LINE__);
+  printf ("The file is %s. \n", __FILE__);
+#line 80 "eev.c"
+  printf ("This is line %d. \n", __LINE__);
+  printf ("The file is %s. \n", __FILE__);
+
+  return 0;
+}

16/16.11.c

@@ -0,0 +1,12 @@
+#include <stdio.h>
+
+#define PRAGMA(X) _Pragma (#X)
+#define LIMRG(X) PRAGMA (STDC CX_LIMITED_RANGE X)
+
+int main (void)
+{
+  LIMRG (ON)
+  printf ("Hello World from LIMRG(ON)\n");
+
+  return 0;
+}

16/16.12.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+#define MYTYPE(X) _Generic \
+((X),                      \
+int: "int",               \
+float: "float",           \
+double: "double",         \
+default: "other"          \
+)
+
+int main (void)
+{
+  int d = 5;
+
+  printf ("%s\n", MYTYPE (d));
+  printf ("%s\n", MYTYPE (2.0 * d));
+  printf ("%s\n", MYTYPE (3L));
+  printf ("%s\n", MYTYPE (&d));
+
+  return 0;
+}

16/16.13.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+
+inline static void eatline (void)
+{
+  while (getchar() != '\n');
+}
+
+int main (void)
+{
+  char str[30];
+
+  printf ("test: \n");
+  scanf ("%s", str);
+  eatline ();
+  printf ("%s\n", str);
+
+  return 0;
+}

16/16.14.c

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <math.h>
+
+#define RAD_TO_DEG (180 / (4 * atan (1)))
+
+typedef struct polar_v
+{
+  double magnitube;
+  double angle;
+} Polar_v;
+
+typedef struct rect_v
+{
+  double x;
+  double y;
+} Rect_v;
+
+Polar_v rect_to_polar (Rect_v);
+
+int main (void)
+{
+  Rect_v input;
+  Polar_v result;
+
+  puts ("Enter x and y coordinates; enter q to quit: ");
+
+  while (scanf ("%lf %lf", &input.x, &input.y) == 2)
+  {
+    result = rect_to_polar (input);
+    printf ("magnitude = %0.2f, angle = %0.2f. \n", result.magnitube, result.angle);
+  }
+
+  printf ("Thank you for using. \n");
+
+  return 0;
+}
+
+Polar_v rect_to_polar (Rect_v rv)
+{
+  Polar_v pv;
+
+  pv.magnitube = sqrt (rv.x * rv.x + rv.y * rv.y);
+
+  if (!pv.magnitube)
+  {
+    pv.angle = 0.0;
+  }else
+  {
+    pv.angle = RAD_TO_DEG * atan2 (rv.y, rv.x);
+  }
+
+  return pv;
+}

16/16.15.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+#include <math.h>
+
+#define RAD_TO_DEG (180 / (4 * atan (1)))
+
+//以下代码和课本上等价;
+#define SQRT(X) _Generic ((X), long double: sqrtl (X), default: sqrt (X), float: sqrtf (X))
+#define SIN(X) _Generic ((X), long double: sinl, default: sin, float: sinf) ((X) / RAD_TO_DEG)
+
+int main (void)
+{
+  float x = 45.0f;
+  double xx = 45.0;
+  long double xxx = 45.0L;
+
+  long double y = SQRT (x);
+  long double yy = SQRT (xx);
+  long double yyy = SQRT (xxx);
+
+  printf ("%.17Lf\n", y);
+  printf ("%.17Lf\n", yy);
+  printf ("%.17Lf\n", yyy);
+
+  int i = 45;
+  yy = SQRT (i);
+  printf ("%.17Lf\n", yy);
+  yyy = SIN (xxx);
+  printf ("%.17Lf\n", yyy);
+
+  return 0;
+}

16/16.16.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+#include <stdlib.h>
+void sign_off (void);
+void too_bad (void);
+
+int main (void)
+{
+  int n;
+
+  atexit (sign_off);
+  printf ("Enter an integer: \n");
+
+  if (scanf ("%d", &n))
+  {
+    printf ("%d is %s. \n", n, (n % 2) ? "odd" : "even");
+  }else
+  {
+    puts ("That's no integer.");
+    atexit (too_bad);
+    exit (EXIT_FAILURE);
+  }
+
+  return 0;
+}
+
+void sign_off (void)
+{
+  printf ("Thus terminates another magnificent program from ");
+  printf ("SeeSaw Software. \n");
+}
+
+void too_bad (void)
+{
+  printf ("SeeSaw Software extends its heartfelt condolences ");
+  printf ("to you upon the failure of your program. \n");
+}

16/16.17.c

@@ -0,0 +1,18 @@
+#include "16.17_18.h"
+
+int main (void)
+{
+  srand ((unsigned int) time (0));
+  double vals[NUM];
+
+  fill_array (vals, NUM);
+
+  printf ("Random list: \n");
+  show_array (vals, NUM);
+
+  printf ("\nSorted list: \n");
+  qsort (vals, NUM, sizeof (double), my_comp);
+  show_array (vals, NUM);
+
+  return 0;
+}

16/16.17_18.h

@@ -0,0 +1,15 @@
+#ifndef _16_17_18_H
+#define _16_17_18_H
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define NUM 40
+
+void fill_array (double ar[], int n);
+void show_array (const double ar[], int n);
+int my_comp (const void * p1, const void * p2);
+
+#endif

16/16.18.c

@@ -0,0 +1,34 @@
+#include "16.17_18.h"
+
+void fill_array (double ar[], int n)
+{
+  for (int index = 0; index < n; index ++)
+  {
+    ar[index] = ((double) rand ()) / ((double) rand () - 0.1);
+  }
+}
+
+void show_array (const double ar[], int n)
+{
+  for (int index = 0; index < n; index ++)
+  {
+    printf ("%9.4f", ar[index]);
+
+    if ((index % 6) == 5)
+    {
+      putchar ('\n');
+    }
+  }
+
+  if (n % 6)
+  {
+    putchar ('\n');
+  }
+}
+
+int my_comp (const void * p1, const void * p2)
+{
+  const double * a1 = (const double *) p1, * a2 = (const double *) p2;
+
+  return (!(*a1 - *a2)) ? 0 : ((*a1 > *a2) ? 1 : -1);
+}

16/16.19.c

@@ -0,0 +1,54 @@
+#include "../s_gets.h"
+
+#define NAME_LEN 40
+
+struct name
+{
+  char f_name[NAME_LEN];
+  char l_name[NAME_LEN];
+};
+
+int comp (const void * p1, const void * p2);
+
+int main (void)
+{
+  struct name names[NAME_LEN];
+  int j;
+
+  printf ("Please enter names. \n");
+  for (j = 0; j < NAME_LEN; j ++)
+  {
+    printf ("Please enter first name: \n");
+    s_gets (names[j].f_name, NAME_LEN);
+    if (!(names[j].f_name[0]))
+    {
+      break;
+    }
+
+    printf ("Please enter last name: \n");
+    s_gets (names[j].l_name, NAME_LEN);
+
+    printf ("Please enter next name. \n");
+  }
+
+  (j != NAME_LEN) ? j ++ : (j = NAME_LEN);
+
+  qsort (names, j, sizeof (names[0]), comp);
+
+  printf ("This is the list of names you've entered: \n");
+  for (int p = 0; p < j; p ++)
+  {
+    printf ("%s %s \n", names[p].f_name, names[p].l_name);
+  }
+
+  return 0;
+}
+
+int comp (const void * p1, const void * p2)
+{
+  const struct name * a1 = (const struct name *) p1, * a2 = (const struct name *) p2;
+
+  return (strcmp (a1 -> f_name, a2 -> f_name)) ?
+  strcmp (a1 -> f_name, a2 -> f_name) :
+  strcmp (a1 -> l_name, a2 ->l_name);
+}

16/16.2.c

@@ -0,0 +1,26 @@
+//预处理器指令从 '#' 开始, 长度为1逻辑行;
+//格式为 "#预处理器指令 宏 替换体";
+
+#include <stdio.h>
+
+#define TWO 2   //可以注释;
+#define OW "Consistency is the last refuge of the unimagina\
+tive.   - Oscar Wi\
+lde"   //反斜杠可以把define延伸一行;
+#define FOUR TWO * TWO
+#define PX printf ("X is %d. \n", x);
+#define FMT "X is %d. \n"
+
+int main (void)
+{
+  int x = TWO;
+
+  PX;
+  x = FOUR;
+  printf (FMT, x);
+  printf ("%s\n", OW);
+  printf ("TWO: OW\n");
+  printf ("%d: %s\n", TWO, OW);
+
+  return 0;
+}