“How to fix ‘Headers already sent’ error in PHP [duplicate]

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• How to fix “Headers already sent” error in PHP 11 answers

Fatal error: Uncaught Error: Call to undefined function mysql_real_escape_string() in C:\xampp\htdocs\Complete\index.php:4 Stack trace: #0 {main} thrown in C:\xampp\htdocs\Complete\index.php on line 4

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