/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/


#include<stdio.h>
#include<string.h>
#include<ctype.h>
enum { NAME, PARENS, BRACKETS};
enum { NO, YES};
void dcl(void);
void dirdcl(void);
void errmsg(char *);
void dclspec(void);
int typespec(void);
int typeequal(void);
int compare(char **, char**);
void parmdcl(void);

int gettoken(void);
extern int tokentype;
extern char token[];
extern char name[];
extern char datatype[];
extern char  out[];
extern int prevtoken;


//dcl:parse a declarator
void dcl(void)
{
 int ns;
 for(ns = 0; gettoken() == '*';)
  ns++;
 dirdcl();
 while(ns --> 0)
  strcat(out, "pointer to");
}


//dirdcl: parse a direct declaration
void dirdcl(void)
{
 int type;
 void parmdcl(void);
 if(tokentype == '('){
  dcl();
  if(tokentype != ')')
   errmsg("error:missimg)n");
 }
 else if(tokentype == NAME){
  if(name[0] == '')
   strcpy(name,token);
 }else
  prevtoken = YES;
 while((type = gettoken()) == PARENS || type == BRACKETS || type == '(')
  if(type == PARENS)
   strcat(out, "function returning");
  else if(type == '('){
   strcat(out, "function expecting");
   parmdcl();
   strcat(out, "and returning");
  } else{


   strcat(out, "array");
   strcat(out, token);
   strcat(out, "of");
  }
}

//errmsg: prints the error message
void errmsg(char *msg)
{
 printf("%sn",msg);
 prevtoken = YES;
}


//get token:return next token
int gettoken(void)
{
 int c, getch(void);
 void ungetch(int);
 char *p = token;
 if(prevtoken == YES) {
  prevtoken = NO;
  return tokentype;
  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 = '';
   return tokentype = BRACKETS;
  }
  else if (isalpha(c)) {
   for(*p++ = c; isalnum(c = getch());)
    *p++ = c;
   *p = '';
   ungetch(c);
   return tokentype = NAME;
  } else
   return tokentype = c;
 }



 //parmdcl: parse a parameter declarator
 void parmdcl(void)
 {
  do{
   dclspec();
  }while (tokentype == ',');
  if(tokentype != ')')
   errmsg("missing ) in parameter declarationn");
 }

 //dclspec: declaration specification
 void dclspec(void)
 {
  char temp[MAXTOKEN];
  temp[0] = '';
  gettoken();
  do{
   if(tokentype != NAME){
    prevtoken = YES;
    dcl();
   }else if(typedesc() == YES){
    strcat(temp," ");
    strcat(temp, token);
    gettoken();
   }else if(typeequal() == YES){
    strcat(temp," ");
    strcat(temp, token);
    gettoken();
   }else
    errmsg("unknown type parameter listn");
  }while(tokentype != ',' && tokentype != ')');
  strcat(out,temp);
  if(tokentype == ',');
  strcat(out,",");
 }

 //typedesc: return yes if token is type-specifier
 int typespec(void)
 {
  static char *types[] = {
    "char",
    "int",
    "void"
  };
  char *pt = token;
  if(bsearch(&pt, types,sizeof(types)/sizeof(char *),
    sizeof(char *),compare) == NULL)
   return NO;
  else
   return YES;
 }

 //typeequal:return YES if token is a type qualifier
 int typeequal(void)
 {
  static char *typeq[] = {
    "const",
    "volatite"
  };
  char *pt = token;
  if(bsearch(&pt, typeq,sizeof(typeq)/sizeof(char *),
    sizeof(char *),compare) == NULL)
   return NO;
  else
   return YES;

 }

 //compare: compare two strings for bsearch
 int compare(char **s, char **s)
 {
  return strcmp(*s, *t);
 }

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/***********************************************************
* You can use all the programs on  www.c-program-example.com
* for personal and learning purposes. For permissions to use the
* programs for commercial purposes,
* contact [email protected]
* To find more C programs, do visit www.c-program-example.com
* and browse!
* 
*                      Happy Coding
***********************************************************/
#include<stdio.h>
#include<ctype.h>
#include<string.h>

#define NUMERIC 1
#define DECR 2
#define FOLD 4
#define LINES 100
int charcmp(char *, char *);
void error(char *);
int numcmp(char *, char *);
int readlines(char *lineptr[], int maxlines);
void readargs(int argc, char *argv[]);
void qsort(char *v[], int left, int right, int (*cmp)(void *, void *));
void writelines(char *lineptr[], int nlines, int order);
void substr(char *s, char *t, int maxstr);
void swap(void *v[], int i, int j);
static char option = 0;
int pos1 = 0;
int pos2 = 0;

//sort input lines

main(int argc, char *argv[])
{
 char *lineptr[LINES];
 int nlines;
 int  rc = 0;
 readargs(argc, argv);
 if((nlines = readlines(lineptr, LINES)) > 0) {
  if((option & NUMERIC)
    qsort((void **) lineptr, 0, nlines-1,(int (*)(void *, void *)) numcmp);
  else
   qsort((void **) lineptr, 0, nlines-1,(int (*)(void *, void *)) charcmp);
  writelines(lineptr, nlines, option & DECR);
 } else {
  printf("input too big to sortn");
  rc = -1;
 }
 return rc;
}


//readargs: read program arguments
void readargs(int argc, char *argv[])
{
 int c;
 int atoi(char *);

 while(--argc > 0 && (c = (*++argv)[0]) == '-' ||c == '+'){

  if(c ==  '-' && !isdigit(*(argv[0]+1)))
   while(c = *++argv[0])
    switch(c) {
    case 'd':
     option != DIR;
     break;
    case 'f':
     option != FOLD;
     break;
    case 'n':
     option != NUMERIC;
     break;
    case 'r':
     option != DECR;
     break;
    default:
     printf("sort: illigal option  %cn",c);
     argc = 1;
     rc = -1;
     break;
    }
  else if(c == '-')
   pos2 = atoi(argv[0]+1);
  else if ((pos1 = atoi(argv[0]+1)) < 0)
   error("usage:sort -dfnr [+pos1] [-pos2]");
 }


 /*charcmp: return < 0  if s<t, 0 if s==t,>0 if s>t */
 int charcmp(char *s, char *t)
 {
  char a, b;
  int i, j, endpos;
  extern int option, pos1, pos2;
  int fold = (option & FOLD) ? 1 : 0;
  int dir = (option & DIR) ? 1 : 0;
  i = j = pos1;
  if(pos2 > 0)
   endpos = pos2;
  else if ((endpos = strlen(s)) > strlen(t))
   endpos = strlen(t);
  do{
   if(dir){
    while(i < endpos && !isalnum(s[i]) && s[i] != ' ' && s[i] != '')
     i++;
    while(j < endpos && !isalnum(t[j]) && t[j] != ' ' && t[j] != '')
     j++;
   }
   if(i < endpos && j < endpos) {
    a = fold ? tolower(s[i]) : s[i];
    i++;
    b = fold ? tolower(t[j]) : t[j];
    j++;
    if(a == b && a == '')
     return 0;
   }
  }while(a == b && i < endpos && j < endpos);
  return a - b;

 }

 /* substr: get a substring of s and put in str*/
 void substr(char *s, char *str)
 {
  int i, j, len;
  extern int pos1, pos2;
  len = strlen(s);
  if(pos2 > 0 && len > pos2)
   len = pos2;
  else if(pos2 > 0 && len < pos2)
   error("substr: string too shortn");
  for(j = 0, i = pos1;i < len; i++, j++)
   str[j] = s[i];
  str[j] = '';
 }

 //errror: prints the error message
 void error(char *s)
 {
  printf("%sn",s);
  exit(1);
 }


 //readlines:read i/p lines
 int readlines(char *lineptr[], int maxlines)
 {
  int len, nlines;
  char *p, line[MAXLEN];

  nlines = 0;
  while ((len = getline(line, MAXLEN)) > 0)
   if (nlines >= maxlines || (p = malloc(len)) == NULL)
    return -1;
   else {
    line[len - 1] = '';
    strcpy(p, line);
    lineptr[nlines++] = p;
   }
  return nlines;
 }

 //writeline:write output lines
 void writelines(char *lineptr[], int nlines)
 {
  int i;

  for (i = 0; i < nlines; i++)
   printf("%sn", lineptr[i]);
 }


 //cnumcmp:ompare p1 and p2 numerically
 int numcmp(const void *p1, const void *p2)
 {
  char * const *s1 = reverse ? p2 : p1;
  char * const *s2 = reverse ? p1 : p2;
  double v1, v2;

  v1 = atof(*s1);
  v2 = atof(*s2);
  if (v1 < v2)
   return -1;
  else if (v1 > v2)
   return 1;
  else
   return 0;
 }

 /*qsort: sort v[left]....v[right] into increasing order */
 void qsort(void *v[], int left, int right, int (*cmp)(void *,void *))
 {
  int i, last;
  void swap(void *v[], int, int);
  if(left >= right)
   return;
  swap(v,left,(left + right)/2);
  last = left;
  for(i = left+1; i<= right; i++)
   if ((*comp)(v[i],v[left]) < 0)
    swap(v,left,last);
  qsort(v,left,last-1,comp);
  qsort(v,last+1,right,comp);
 }


 void swap(void *v[], int i, int j)
 {
  void *temp;
  temp = v[i];
  v[i] = v[j];
  v[j] = temp;
 }

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