i copied files into directories structured as recommended. but captcha does not display on register.php page. also if u fill in fields but leave 'verify' field [where you enter captcha text] blank, registration works fine. since i copied the files from the website, there are no typos by myself in the code. any ideas?

Hi,

When writing an image such as the captcha image, you have
to be careful not to send any other output to the browser.
In captcha.php, if you are using print statements for
debugging it is best to take them out. Also, if you have
blank lines after the <?php ?> tags these can get sent
to the browser and cause problems as well.

The thing that can make debugging a little bit difficult
in the case of writing images,
is that it may not be the code logic that is causing the problem;
having other output going to the browser, such as
print statements and blanks lines, can cause the image to
not come out.

See posts

Chap 1 - captcha.php and debugging statements

Chap 9, Debugging issues, and graphs not showing up.

There have been some mistakes in this chapter. I don't know
if they have corrected them since the last time I used them, but
it would be a good idea to check through errata and this
P2P forum.

I hope this helps.

thank you kenj. I have doubled checked the .php files. I downloaded them all from this website and copied them into the recommended directory structure. I have not added any debugging statements to the files. Just in case, i have closed up any single line gaps in the code in the functions.php and captcha.php files plus the html section of the register.php file. This has not rectified the issue. I have also checked the errata but there is nothing for chapter 1, captcha. When i first logged in here several weeks ago, i remember seeing a posting where someone complained of this issue and they copied an alternative captcha.php code file which they created and which worked. I have done a search but i have not located that posting. I am not sure why that posting has disappeared. It might solve this matter if someone could help me to retrieve that posting?

Thank you Andrew.

I downloaded the current captcha.php
file and it appears to be the same as
the one I am using. In the functions
file, captcha.php uses random_text function,
which also appears to be the same as I
am using. Your code should be the
same as mine, and mine is working.
Just to make sure, I did another test;
I replaced my existing captcha.php and
functions.php with these downloaded files.
It worked for me, I was able to see the
captcha image. I was sure to clear temporary
Internet files and cache.

I am wondering if it might have something
to do with system configuration.

I am using

UNIX 4.10-RELEASE FreeBSD
PHP version 5.2.14

At this point, a good test might be to see
if imagepng can write to a file.
Change the imagepng statement, around line 38, to
Browse to register.php
Then go to the public_files/img directory
and see if myfile.png is there.
If it is, see if it will display in the browser
http://mydomain/myapp/public_files/img/myfile.png

Be sure to change that line back again.

If it does display correctly,
then you would have to look at issues around imagepng.
The imagepng function writes to a temporary file which
gets sent to the browser. Perhaps Php does not
have permission to write to the temporary file
or something like that. There is a lot of discussion
about this type of problem on the net.

If it does not display correctly, then you'd
need to go through your code line by line and
see where it is not working.

You may have already done this test,
but I thought I'd post it here anyway
in case anyone else may be interested.

Let us know what happens. Thanks.

hello Kenj, thank you for another useful response. I have wrestled with this problem for the last 24 hours and managed to solve it. I tried using captcha source files from php.net and i managed to get a few images working. Eventually I tried out the ch.1 .php files in my browser and the captcha image displayed perfectly. After following so many different paths I was unsure what had caused the image to display all of a sudden.

Your testing is a useful tool. I think you identify the problem when you mention clearing the browser cache.