Exc. 6_01

chapter_6.structures/6_1.getword/Makefile

@@ -0,0 +1,3 @@
+BINARY=getword
+
+include ../../Exercise_incl.mk

chapter_6.structures/6_1.getword/binsearch.c

@@ -0,0 +1,21 @@
+# include <string.h>
+# include "binsearch.h"
+
+/* binsearch: find word in tab[0]...tab[n-1] */
+int binsearch (char *word, struct key tab[], int n)
+{
+  int cond;
+  int low, high, mid;
+  low = 0;
+  high = n - 1;
+  while (low <= high) {
+    mid = (low+high) / 2;
+    if ((cond = strcmp(word, tab[mid].word)) < 0)
+      high = mid - 1;
+    else if (cond > 0)
+      low = mid + 1;
+    else
+      return mid;
+  }
+  return -1;
+}

chapter_6.structures/6_1.getword/binsearch.h

@@ -0,0 +1,12 @@
+# ifndef BINSEARCH_H
+# define BINSEARCH_H
+
+struct key {
+  char *word;
+  int count;
+};
+
+/* binsearch: find word in tab[0]...tab[n-1] */
+int binsearch (char *word, struct key tab[], int n);
+
+# endif

chapter_6.structures/6_1.getword/getch.c

@@ -0,0 +1,25 @@
+# include <stdio.h>
+
+# define BUFSIZE 128
+
+int buf[BUFSIZE];    /* buffer for ungetch */
+int bufp = 0;        /* next free position in buf */
+
+
+/* getch: get a (possibly pushed-back) character */
+int getch (void)
+{
+  return (bufp > 0) ? buf[--bufp] : getchar();
+}
+
+
+/* ungetch: push character back on input */
+void ungetch (int c)
+{
+  if (bufp >= BUFSIZE) {
+    printf("ungetch: too many characters\n");
+  } else {
+    buf[bufp++] = c;
+  }
+}
+

chapter_6.structures/6_1.getword/getch.h

@@ -0,0 +1,9 @@
+# ifndef GETCH_H
+# define GETCH_H
+
+/* getch: get a (possibly pushed-back) character */
+int getch (void);
+/* ungetch: push character back on input */
+void ungetch (int c);
+
+# endif

chapter_6.structures/6_1.getword/getword.c

@@ -0,0 +1,106 @@
+# include <stdio.h>
+# include <ctype.h>
+# include "getch.h"
+
+/*
+  Our version of getword does not properly handle underscores, string
+  constants, comments, or preprocessor control lines. Write a better version.
+*/
+
+int ignore_nonwords ()
+{
+  int c = getch();
+
+  /* ignore white spaces */
+  if (isspace(c)) {
+    while (isspace(c = getch()))
+      ;
+    ungetch(c);
+    return 1;
+  }
+
+  /* ignore character constants */
+  if (c == '\'') {
+    do {
+      if ((c = getch()) == '\\') {
+        getch();
+        c = getch();
+      }
+    } while (c != '\'' && c != EOF);
+    return 1;
+  }
+
+  /* ignore string constants */
+  if (c == '"') {
+    do {
+      if ((c = getch()) == '\\') {
+        getch();
+        c = getch();
+      }
+    } while (c != '"' && c != EOF);
+    return 1;
+  }
+
+  /* ignore preprocessor commands */
+  if (c == '#') {
+    while ((c = getch()) != EOF && c != '\n')
+      if ((c = getch()) == '\\') {
+        if ((c = getch()) == '\n')
+          c = getch();
+        else
+          ungetch(c);
+      }
+    return 1;
+  }
+
+  /* ignore comments */
+  if (c == '/') {
+    if ((c = getch()) == '*') {
+      while (c != EOF)
+        if ((c = getch()) == '*') {
+          if ((c = getch()) == '/')
+            break;
+          else
+            ungetch(c);
+        }
+      return 1;
+    }
+    else
+      ungetch(c);
+  }
+
+  /* ignore numbers */
+  if (isdigit(c)) {
+    while (isdigit(c = getch()) || c == '.')
+      ;
+    ungetch(c);
+    return 1;
+  }
+
+  ungetch(c);
+  return 0;
+}
+
+/* getword: get next word or character from input */
+int getword (char *word, int lim)
+{
+  int c;
+  char *w = word;
+
+  while (ignore_nonwords())
+    ;
+
+  if ((c = getch()) != EOF)
+    *w++ = c;  
+  if (!isalpha(c) && c!='_') {
+    *w = '\0';
+    return c;
+  }
+  for ( ; --lim > 0; w++)
+    if (!isalnum(*w = getch()) && *w!='_') {
+      ungetch(*w);
+      break;
+    }
+  *w = '\0';
+  return word[0];
+}

chapter_6.structures/6_1.getword/getword.h

@@ -0,0 +1,7 @@
+# ifndef GETWORD_H
+# define GETWORD_H
+
+/* getword: get next word or character from input */
+int getword (char *word, int lim);
+
+# endif

chapter_6.structures/6_1.getword/main.c

@@ -0,0 +1,59 @@
+# include <stdio.h>
+# include <ctype.h>
+# include <string.h>
+# include "getword.h"
+# include "binsearch.h"
+
+struct key keytab[] = {
+  {"auto", 0},
+  {"break", 0},
+  {"case", 0},
+  {"char", 0},
+  {"const", 0},
+  {"continue", 0},
+  {"default", 0},
+  {"do", 0},
+  {"double", 0},
+  {"else", 0},
+  {"enum", 0},
+  {"extern", 0},
+  {"float", 0},
+  {"for", 0},
+  {"goto", 0},
+  {"if", 0},
+  {"int", 0},
+  {"long", 0},
+  {"register", 0},
+  {"return", 0},
+  {"short", 0},
+  {"signed", 0},
+  {"sizeof", 0},
+  {"static", 0},
+  {"struct", 0},
+  {"switch", 0},
+  {"typedef", 0},
+  {"union", 0},
+  {"unsigned", 0},
+  {"void", 0},
+  {"volatile", 0},
+  {"while", 0}
+};
+
+# define NKEYS (int)(sizeof keytab / sizeof(struct key))
+# define MAXWORD 128
+
+/* count C keywords */
+int main ()
+{
+  int n;
+  char word[MAXWORD];
+  while (getword(word, MAXWORD) != EOF)
+    if (isalpha(word[0]))
+      if ((n = binsearch(word, keytab, NKEYS)) >= 0)
+        keytab[n].count++;
+  for (n = 0; n < NKEYS; n++)
+    if (keytab[n].count > 0)
+      printf("%4d %s\n",
+             keytab[n].count, keytab[n].word);
+  return 0;
+}

chapter_6.structures/6_1.getword/tests/0_getch.tin

@@ -0,0 +1,9 @@
+# ifndef GETCH_H
+# define GETCH_H
+
+/* getch: get a (possibly pushed-back) character */
+int getch (void);
+/* ungetch: push character back on input */
+void ungetch (int c);
+
+# endif

chapter_6.structures/6_1.getword/tests/0_getch.tout

@@ -0,0 +1,2 @@
+   2 int
+   2 void

chapter_6.structures/6_1.getword/tests/1_main.tin

@@ -0,0 +1,59 @@
+# include <stdio.h>
+# include <ctype.h>
+# include <string.h>
+# include "getword.h"
+# include "binsearch.h"
+
+struct key keytab[] = {
+  {"auto", 0},
+  {"break", 0},
+  {"case", 0},
+  {"char", 0},
+  {"const", 0},
+  {"continue", 0},
+  {"default", 0},
+  {"do", 0},
+  {"double", 0},
+  {"else", 0},
+  {"enum", 0},
+  {"extern", 0},
+  {"float", 0},
+  {"for", 0},
+  {"goto", 0},
+  {"if", 0},
+  {"int", 0},
+  {"long", 0},
+  {"register", 0},
+  {"return", 0},
+  {"short", 0},
+  {"signed", 0},
+  {"sizeof", 0},
+  {"static", 0},
+  {"struct", 0},
+  {"switch", 0},
+  {"typedef", 0},
+  {"union", 0},
+  {"unsigned", 0},
+  {"void", 0},
+  {"volatile", 0},
+  {"while", 0}
+};
+
+# define NKEYS (int)(sizeof keytab / sizeof(struct key))
+# define MAXWORD 128
+
+/* count C keywords */
+int main ()
+{
+  int n;
+  char word[MAXWORD];
+  while (getword(word, MAXWORD) != EOF)
+    if (isalpha(word[0]))
+      if ((n = binsearch(word, keytab, NKEYS)) >= 0)
+        keytab[n].count++;
+  for (n = 0; n < NKEYS; n++)
+    if (keytab[n].count > 0)
+      printf("%4d %s\n",
+             keytab[n].count, keytab[n].word);
+  return 0;
+}

chapter_6.structures/6_1.getword/tests/1_main.tout

@@ -0,0 +1,7 @@
+   1 char
+   1 for
+   3 if
+   2 int
+   1 return
+   1 struct
+   1 while

chapter_6.structures/6_1.getword/tests/2_binsearch.tin

@@ -0,0 +1,21 @@
+# include <string.h>
+# include "binsearch.h"
+
+/* binsearch: find word in tab[0]...tab[n-1] */
+int binsearch (char *word, struct key tab[], int n)
+{
+  int cond;
+  int low, high, mid;
+  low = 0;
+  high = n - 1;
+  while (low <= high) {
+    mid = (low+high) / 2;
+    if ((cond = strcmp(word, tab[mid].word)) < 0)
+      high = mid - 1;
+    else if (cond > 0)
+      low = mid + 1;
+    else
+      return mid;
+  }
+  return -1;
+}

chapter_6.structures/6_1.getword/tests/2_binsearch.tout

@@ -0,0 +1,7 @@
+   1 char
+   2 else
+   2 if
+   4 int
+   2 return
+   1 struct
+   1 while

chapter_6.structures/Makefile

@@ -0,0 +1,3 @@
+SUBDIRS=$(wildcard 6_*/)
+
+include ../Chapter_incl.mk