wp-admin/includes/class-wp-filesystem-direct.php:65Writes a string to a file.
$filestring$contentsstring$modeint|falseoptionalfalsebool public function put_contents( $file, $contents, $mode = false ) { $fp = @fopen( $file, 'wb' ); if ( ! $fp ) { return false; } mbstring_binary_safe_encoding(); $data_length = strlen( $contents ); $bytes_written = fwrite( $fp, $contents ); reset_mbstring_encoding(); fclose( $fp ); if ( $data_length !== $bytes_written ) { return false; } $this->chmod( $file, $mode ); return true; }Introduced in 2.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-filesystem-direct.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.