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CGI with C

Posted on 1998-02-25
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Last Modified: 2013-12-25
I am going to test a CGI-script. I've written two files:
1) test.html
********************************
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Developer Studio">
<META HTTP-EQUIV="Content-Type" content="text/html; charset=iso-8859-1">
<TITLE>Document Title</TITLE>
</HEAD>
<BODY>

<!-- Insert HTML here -->
<form method=get action="test.cgi">
Enter some text here:<br>
<input type="text" name="sometext" value="">
<p>
<input type="submit" value="Send">
</form>

</BODY>
</HTML>
********************************

2) test.c
********************************
#include <stdio.h>
#include <stdlib.h>

void header(), footer();

int main()
{
      header();
      printf("Querry String: %s\n\n", getenv("QUERY_STRING"));
      footer();

      return 0;
}

void header()
{
      printf("Content-type: text/html\n\n");
      printf("<html>\n");
      printf("<head>\n<title>Example CGI Output</title>\n</head>\n");
      printf("<body>\n\n");
}

void footer()
{
      printf("</body>\n");
      printf("</html>\n");
}
********************************

I build the c-fiel successed and get "test.exe". I change it to "test.cgi". Then I haven't permit to our server, so I save the files under the same directory.

I open the "test.html" with Netscape browser. I tip some text in the input window. But as I click the "Sene"-button, it shows some strange text which I can't understand.

How can I solve the problem?


chen wei

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Comment
Question by:chenwei
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  • 2
6 Comments
 

Author Comment

by:chenwei
ID: 1832032
Edited text of question
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Author Comment

by:chenwei
ID: 1832033
Edited text of question
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LVL 5

Expert Comment

by:julio011597
ID: 1832034
Your program should show something like:

sometext=the_text_you_typed_in

with sequences of "%xx" (where xx is the ASCII code in hexadecimal) replacing any non-printable chars.

If this is what you get, then this is how CGI works.
You need your string parsing routines to exctract and decode key-value pairs from the query string.

BTW, the getenv() function can fail and return NULL, so you should do something like:

--
int main(void) {
  char *query_string = getenv("QUERY_STRING");

  header();

  if(query_string) printf("Query string: %s\n", query_string);
  else puts("Cannot get query string!");

  footer();

  return 0;
}
--//--

Cheers.
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Author Comment

by:chenwei
ID: 1832035
First I would like to thank julio's answer. But it dosen't help.
I was told (and I am sure) that the files I wrote are correct. The problem may be that I should save the cgi-file(test.cgi) under the directory:/cgi-bin by the server, then the cgi-script can only be executed by server not by client. But I haven't the access to the server.

I do want to test the cgi-scripts I have written, but I don't know where and how.
0
 
LVL 1

Expert Comment

by:Michel021497
ID: 1832036
I think you should ask your provider for a solution for this problem. He can give you access to your cgi-bin directory.
0
 
LVL 5

Accepted Solution

by:
julio011597 earned 50 total points
ID: 1832037
Yes chenwei, CGI is a protocol stating how a web server can communicate with an external program; i.e., no server... no CGI.

To test your scripts locally, you should install a web server on your PC and work with it (you can download a web server for free from both Netscape and Microsoft).

Anyway, as Michel says, you could first try to talk to your Internet Provider and see if they can help you.
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