Verification code problems

Verification code question session_start ();
// Number of random codes
$ _ Rnd_code = 4;

// Create a random code
For ($ I = 0; $ I <$ _ rnd_code; $ I ++ ){
$ _ Nmsg. = dechex (mt_rand (0, 15 ));
}

// Save it in the session
$ _ SESSION ['code'] =$ _ nmsg;

// Set the length and height
$ _ Width = 75;
$ _ Height = 25;

// Create an image
$ _ Img = imagecreatetruecolor ($ _ width, $ _ height );

// White
$ _ White = imagecolorallocate ($ _ img, 255,255,255 );

// Fill
Imagefill ($ _ img, 0, 0, $ _ white );

// Black border
$ _ Black = imagecolorallocate ($ _ img, 0, 0 );
Imagerectangle ($ _ img, 0, 0, $ _ width-1, $ _ height-1, $ _ black );

// Random six lines
For ($ I = 0; $ I <6; $ I ++ ){
$ _ Rnd_color = imagecolorallocate ($ _ img, mt_rand (0,255), mt_rand (0,255), mt_rand (0,255 ));
Imageline ($ _ img, rand (0, $ _ width), rand (0, $ _ height), rand (0, $ _ width), rand (0, $ _ height), $ _ rnd_color );

}
// Output the verification code

For ($ I = 0; $ I Imagestring ($ _ img, 5, $ I * $ _ width/$ _ rnd_code + mt_rand (1, 10), mt_rand (1, $ _ height/2 ), $ _ SESSION ['code'] ['$ I'], $ _ black );

}
The four characters output from a verification code result are all the same. let's take a look at what's going on.

Reply to discussion (solution)

Imagestring ($ _ img, 5, $ I * $ _ width/$ _ rnd_code + mt_rand (1, 10), mt_rand (1, $ _ height/2 ), $ _ SESSION ['code'] ['$ I'], $ _ black );
This should be the case
Imagestring ($ _ img, 5, $ I * $ _ width/$ _ rnd_code + mt_rand (1, 10), mt_rand (1, $ _ height/2 ), $ _ SESSION ['code'] [$ I], $ _ black );

(! ) Notice: Undefined variable: _ nmsg in \ demo. php on line 10
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main} () .. \ demo. php: 0

(! ) Warning: Illegal string offset '$ I' in \ demo. php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main} () .. \ demo. php: 0

(! ) Warning: Illegal string offset '$ I' in \ demo. php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main} () .. \ demo. php: 0

(! ) Warning: Illegal string offset '$ I' in \ demo. php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main} () .. \ demo. php: 0

(! ) Warning: Illegal string offset '$ I' in \ demo. php on line 42
Call Stack
# Time Memory Function Location
1 0.0006 146856 {main} () .. \ demo. php: 0



Change it to this.

Thank you for making the money.