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ercis

Posted on 2000-02-24
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Last Modified: 2010-04-02
Please answer this for your points.
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Question by:rkcth
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6 Comments
 
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Expert Comment

by:nietod
ID: 2556603
I believe this is for

http://www.experts-exchange.com/jsp/qShow.jsp?ta=cplusprog&qid=10299447 

correct?  (Always good to provide "justification".)
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Accepted Solution

by:
ercis earned 50 total points
ID: 2559893
/***

this will do more: create 1x1 dot with specified color...
compile: gcc -Wall -s -o dot.cgi dot.c
and write in html:
 <img src="http://host.com/cgi-bin/dot.cgi?FF0000" width="50" height="5">

***/


#include <stdio.h>
#include <stdlib.h>

char x2c(char *what) {
   register char digit;
   digit = (what[0] >= 'A' ? ((what[0] & 0xdf) - 'A')+10 : (what[0] - '0'));
   digit *= 16;
   digit += (what[1] >= 'A' ? ((what[1] & 0xdf) - 'A')+10 : (what[1] - '0'));
   return(digit);
}

const unsigned char IMAGE_GIF1[] = {
   0x47, 0x49, 0x46, 0x38, 0x39, 0x61, 0x01, 0x00,
   0x01, 0x00, 0x80, 0xFF, 0x00, 0xFF, 0xFF, 0xFF };

const unsigned char IMAGE_GIF2[] = {
                     0x2C, 0x00, 0x00, 0x00, 0x00,
   0x01, 0x00, 0x01, 0x00, 0x00, 0x02, 0x02, 0x4C,
   0x01, 0x00, 0x3B };

int main(int argc, char *argv[])
{
   char *input, *p, *e;
   long l1 = sizeof(IMAGE_GIF1);
   long l2 = sizeof(IMAGE_GIF2);


   if( (p=getenv("REQUEST_METHOD")) && !strcmp(p, "GET") &&
       (p=getenv("QUERY_STRING")) && strlen(p) > 5 )
      input = p;
   else
      if(argc > 1 && strlen(argv[1]) > 5)  input = argv[1];
         else
            input = "ffffff";  // default = white

   printf("Content-type: image/gif\r\n");
   printf("Content-Length: %lu\r\n\r\n", l1 + 3 + l2);

   p = (char *)IMAGE_GIF1;
   e = p + l1;

   do
   {
     putchar(*p);
   }
   while (++p < e);

   putchar(x2c(input));
   putchar(x2c(input + 2));
   putchar(x2c(input + 4));

   p = (char *)IMAGE_GIF2;
   e = p + l2;

   do
   {
     putchar(*p);
   }
   while (++p < e);

   exit(0);
}

// nietod can make some optimizations :)
// maybe fwrite(IMAGE_GIF, sizeof(IMAGE_GIF), 1, stdout);
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LVL 22

Expert Comment

by:nietod
ID: 2560921
Instead of

p = (char *)IMAGE_GIF1;
e = p + l1;

do
{
   putchar(*p);
}
while (++p < e);

I would just do

cout.write(IMAGE_GIF1,sizeof(IMAGE_GIF1));

it is simpler and likely to be faster.
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LVL 1

Expert Comment

by:ercis
ID: 2562971
yes, but I'm talking about C, not C++
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LVL 22

Expert Comment

by:nietod
ID: 2562994
But this is the C++ topic area.  We kill for less.  :-)
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LVL 1

Expert Comment

by:ercis
ID: 2563462
nietod: sorry, I omited that :)
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