Thread: Question about a declaration

Here's a breakdown of the function, much easier to see and understand because someone neglected to create readable code ():

typedef void (handler_t)(int);
typedef void (signal_return_t)(int);
signal_return_t* signal(int sig, handler_t* handler);

There's actually a program in The C Programming Language that splits declarations like this . . . it starts on page 90 of this: http://www.ica.luz.ve/dfinol/tpro/kandr.pdf

Since that's probably an illegal copy of the book, I've copied the code here for you:

Code:

/* From The C Programming Language */

#include <stdio.h>
#include <string.h>
#include <ctype.h>

#define BUFSIZE 100
char buf[BUFSIZE];     /* buffer for ungetch */
int bufp = 0;          /* next free position in buf */
int getch(void) /* get a (possibly pushed-back) character */
{
    return (bufp > 0) ? buf[--bufp] : getchar();
}
void ungetch(int c)    /* push character back on input */
{
    if (bufp >= BUFSIZE)
         printf("ungetch: too many characters\n");
    else
         buf[bufp++] = c;
}

#define MAXTOKEN   100
enum { NAME, PARENS, BRACKETS };
void dcl(void);
void dirdcl(void);
int gettoken(void);
int tokentype;             /* type of last token */
char token[MAXTOKEN];      /* last token string */
char name[MAXTOKEN];       /* identifier name */
char datatype[MAXTOKEN];   /* data type = char, int, etc. */
char out[1000];
main() /* convert declaration to words */
{
    while (gettoken() != EOF) {     /* 1st token on line */
        strcpy(datatype, token); /* is the datatype */
        out[0] = '\0';
        dcl();         /* parse rest of line */
        if (tokentype != '\n')
            printf("syntax error\n");
        printf("&#37;s: %s %s\n", name, out, datatype);
    }
    return 0;
}

/* dcl: parse a declarator */
void dcl(void)
{
    int ns;
    for (ns = 0; gettoken() == '*'; ) /* count *'s */
         ns++;
    dirdcl();
    while (ns-- > 0)
         strcat(out, " pointer to");
}
/* dirdcl: parse a direct declarator */
void dirdcl(void)
{
    int type;
    if (tokentype == '(') {          /* ( dcl ) */
         dcl();
         if (tokentype != ')')
             printf("error: missing )\n");
    } else if (tokentype == NAME) /* variable name */
         strcpy(name, token);
    else
         printf("error: expected name or (dcl)\n");
    while ((type=gettoken()) == PARENS || type == BRACKETS)
  if (type == PARENS)
      strcat(out, " function returning");
  else {
      strcat(out, " array");
      strcat(out, token);
      strcat(out, " of");
  }
}

int gettoken(void) /* return next token */
{
    int c, getch(void);
    void ungetch(int);
    char *p = token;
    while ((c = getch()) == ' ' || c == '\t')
        ;
    if (c == '(') {
        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;
}

It doesn't work as well I remember it doing . . . I must have improved it, but I can't find where I put my version.