Exerc 5_19.

chapter_5.pointers_arrays/5_19.undcl_parens_fix/Makefile

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+BINARY=undcl_parens_fix
+
+include ../../Exercise_incl.mk

chapter_5.pointers_arrays/5_19.undcl_parens_fix/getch.c

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+# 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_5.pointers_arrays/5_19.undcl_parens_fix/getch.h

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+# 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_5.pointers_arrays/5_19.undcl_parens_fix/gettoken.c

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+# include <string.h>
+# include <ctype.h>
+
+# include "gettoken.h"
+# include "getch.h"
+
+int tokentype; /* type of last token */
+char token[MAXTOKEN]; /* last token string */
+
+/* ignspaces: ignore white space characters (' ', '\t') */
+void ignspaces (void)
+{
+  int c;
+  while ((c = getch()) == ' ' || c == '\t')
+    ;
+  ungetch(c);
+}
+
+/* gettoken: return next token */
+int gettoken (void)
+{
+  int c;
+  char *p = token;
+
+  ignspaces();
+  if ((c = getch()) == '(') {
+    ignspaces();
+    if ((c = getch()) == ')') {
+      strcpy(token, "()");
+      return tokentype = PARENS;
+    }
+    else {
+      ungetch(c);
+      return tokentype = '(';
+    }
+  }
+  else if (c == '[') {
+    for (*p++ = c; (*p++ = getch()) != ']'; )
+      ;
+    *p = '\0';
+    return tokentype = BRACKETS;
+  }
+  else if (isalpha(c)) {
+    for (*p++ = c; isalnum(c = getch()); )
+      *p++ = c;
+    *p = '\0';
+    ungetch(c);
+    return tokentype = NAME;
+  }
+  else
+    return tokentype = c;
+}

chapter_5.pointers_arrays/5_19.undcl_parens_fix/gettoken.h

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+# ifndef GETTOKEN_H
+# define GETTOKEN_H
+
+# define MAXTOKEN 1024
+
+enum {NAME, PARENS, BRACKETS};
+
+extern int tokentype; /* type of last token */
+extern char token[MAXTOKEN]; /* last token string */
+
+/* gettoken: return next token */
+int gettoken (void);
+
+# endif

chapter_5.pointers_arrays/5_19.undcl_parens_fix/main.c

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+# include <stdio.h>
+# include <string.h>
+
+# include "gettoken.h"
+
+# define MAXOUT 1024
+
+char out[MAXOUT];
+
+/* undcl: convert word descriptions to declarations */
+int main ()
+{
+  int type;
+  char temp[MAXTOKEN];
+
+  while (gettoken() != EOF) {
+    strcpy(out, token);
+    while ((type = gettoken()) != '\n')
+      if (type == PARENS || type == BRACKETS)
+        strcat(out, token);
+      else if (type == '*') {
+        if (strlen(out)+1+3 > sizeof(temp))
+          strcat(out, "internal error #0");
+        else {
+          strcpy(temp, "(*");
+          strcat(temp, out);
+          strcat(temp, ")");
+          strcpy(out, temp);
+        }
+      }
+      else if (type == NAME) {
+        if (strlen(temp)+1 > sizeof(temp)) {
+          strcat(out, "internal error #1");
+        }
+        else if (strlen(out) + strlen(token) + 1 > sizeof(temp)) {
+          strcat(out, "internal error #2");
+        }
+        else {
+          strcpy(temp, token);
+          strcat(temp, " ");
+          strcat(temp, out);
+          strcpy(out, temp);
+        }
+      }
+      else
+        printf("invalid input at %s\n", token);
+    printf("%s\n", out);
+  }
+  return 0;
+}

chapter_5.pointers_arrays/5_19.undcl_parens_fix/tests/t0.tin

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+x () * [] * () char

chapter_5.pointers_arrays/5_19.undcl_parens_fix/tests/t0.tout

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+char (*(*x())[])()