captcha error Warning: session_start() [function.session-start]:Cannot send session cache limiter - headers already sent (output started at [closed]

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Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\xampp\htdocs\program\sanweetha\quotation.php:280) in C:\xampp\htdocs\program\sanwe开发者_运维技巧etha\php\captcha demo\captcha_demo.php on line 1

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This error indicates that you are attempting to use the function session_start() at some point after you have started to send output to the user. Nothing can be output to the user before you use the function, not even whitespace. Check that your script begins with <?php and that you are not outputting inline HTML anywhere before the function call, nor using echo or similar.

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you may have attempted to send a HTTP header to the browser after the script has generated a line of output. This ain't good as the PHP manual succinctly puts it, "...you can not normally send headers to the browser after data has already been sent...".

So either make sure to use http header before any output generated

OR

One can use ob_start(); at the beginning of the script, this will put all generated output to the buffer thus output of screen will not seen