Simple, dirty URL decode in C

/*******************************************************************************
 * urlde.c
 * Commandline URL deocde - fast and dirty
 * by tovis 2011
 * Build: make urlde and strip urlde
 * Usage: cat or echo "url coded text" | urlde
*******************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>

//******************************************************************************
int			main(int c,char *argv[])
{
  int		ichr = 0;
  char		shex[3];
  //... code ...
  do
  {
    ichr = getchar();
    switch ( ichr )
    {
    case '+':
      ichr = ' ';
      break;
    case '%':
      ichr = getchar();
      if ( ichr != '%' )
      {
        memset(shex,0,sizeof(shex));
        shex[0] = (char)ichr;
        shex[1] = (char)getchar();
        if ( !isxdigit(shex[0]) || !isxdigit(shex[1]) )
          ichr = '?';
        else
        {
          ichr  = 0;
          ichr  = ( shex[0] > 0x39 ) ? (shex[0] - 0x37 ) : (shex[0] - 0x30 );
          ichr  = ichr << 4;
          ichr += ( shex[1] > 0x39 ) ? (shex[1] - 0x37 ) : (shex[1] - 0x30 );
          if ( ichr == '\n' )
          {
            putchar(ichr);
            ichr = 0;
            continue;
          }
        }
      }
      break;
    default:
      break;
    }
    putchar(ichr);
  } while ( ichr != '\n' );
  exit ( 0 );
} //end main

/*******************************************************************************
 * end urlde.c
*******************************************************************************/