Add functions for validating longitudes and latitutdes

exceptions/MDCoordinateOutOfRange.php

@@ -0,0 +1,20 @@
+<?PHP
+declare(strict_types = 1);
+
+/**
+ * Custom exception class for coordinates (longitude, latitude) that are out
+ * of range (-90 - 90 for latitudes, -180 to 180 for longitudes).
+ */
+final class MDCoordinateOutOfRange extends MDExpectedException {
+    /**
+     * Error message.
+     *
+     * @return string
+     */
+    public function errorMessage() {
+        //error message
+        $errorMsg = 'Parameter: <b>' . $this->getMessage() . '</b> is not a valid, numeric values.';
+        return $errorMsg;
+
+    }
+}

src/MD_STD_IN.php

@@ -295,6 +295,46 @@ final class MD_STD_IN {
 
     }
 
+    /**
+     * Validates a coordinate.
+     *
+     * @param string|integer $input Input string.
+     *
+     * @return float
+     */
+    public static function validate_longitude(string|int $input):float {
+
+        if (is_string($input)) $output = self::sanitize_float($input);
+        else $output = $input;
+
+        if ($output < -180 || $output > 180) {
+            throw new MDCoordinateOutOfRange("Longitude out of range");
+        }
+
+        return $output;
+
+    }
+
+    /**
+     * Validates a coordinate.
+     *
+     * @param string|integer $input Input string.
+     *
+     * @return float
+     */
+    public static function validate_latitude(string|int $input):float {
+
+        if (is_string($input)) $output = self::sanitize_float($input);
+        else $output = $input;
+
+        if ($output < -90 || $output > 90) {
+            throw new MDCoordinateOutOfRange("Latitude out of range");
+        }
+
+        return $output;
+
+    }
+
     /**
      * Validates ISBNs. Empty strings are accepted as well.
      *