Notice: Use of undefined constant xxx?

[PHPQuack]

I tried the following scripts, both returning true, but both are also giving similar errors. I'm just testing locally on my xp system. What am I missing?

i.e. Notice: Use of undefined constant mysqli_connect - assumed 'mysqli_connect' in C:\Inetpub\wwwroot\php\test.php on line 2

Call Stack:
0.2106 50944 1. {main}() C:\Inetpub\wwwroot\php\test.php:0

<?php
if (function_exists(gd_info))
{
    print "Yes";
} else {
    print "No";
}

?>

<?php
if (function_exists(mysqli_connect))
{
    print "Yes";
} else {
    print "No";
}
?>

[NogDog]

if(function_exists([color=red][b]"[/b][/color]mysqli_connect[color=red][b]"[/b][/color]))

[PHPQuack]

Ahhhh, thank you. I read the function_exist in a book, which was missing the quotes, while not noticing that the parameter needs to be a string in the php.net manual,

Cool