parse.c

HTML语言的例子

/* parse.c */
#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include "parse.h"

/* Build a string of up to the specified size from the standard input. */
char *build(int size, char delim, int *len)
{
  register int i;
  char *gen,hex2c[2];

/* Allocate space for the data according to requested size. */
  if(!(gen=malloc(sizeof(char)*(size+1))))
    return gen;

/* As long as there is still input, keep going. */
  for(i=0; (*len); i++){
    if(i>size+1){
/* Data item is larger than requested size. */
      free(gen);
      return (char *)NULL;
    }
    gen[i]=(char)getchar();
    --(*len);
    if((gen[i] == delim) || (gen[i]==EOF)){
/* Found the end of the current input field. Terminate and return the
   parsed field. */
      gen[i]='\0';
      return gen;
    }
/* Convert plus sign to space. */
    if(gen[i]=='+')
      gen[i]=' ';
/* Convert an escaped special character back to an ASCII character. */
    if(gen[i]=='%'){
      hex2c[0]=getchar();
      --(*len);
      hex2c[1]=getchar();
      --(*len);
      gen[i] = (!(isalpha(hex2c[0])) ? (hex2c[0] - '0') :
		((hex2c[0] & 0xdf) - 'A' + 10)) << 4;
      gen[i] += (!(isalpha(hex2c[1])) ? (hex2c[1] - '0') :
		 ((hex2c[1] & 0xdf) - 'A' + 10));
    }
  }

/* Reached the end of the input block. Terminate and return the string. */
  gen[i]='\0';
  return gen;
}