Simplified Rust code to use += operator instead of String.push_str().

rust/src/lib.rs

@@ -238,13 +238,13 @@ impl QrCode {
 	pub fn to_svg_string(&self, border: i32) -> String {
 		assert!(border >= 0, "Border must be non-negative");
 		let mut result: String = String::new();
-		result.push_str("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
-		result.push_str("<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n");
+		result += "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+		result += "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n";
 		let dimension = self.size.checked_add(border.checked_mul(2).unwrap()).unwrap();
-		result.push_str(&format!(
-			"<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" viewBox=\"0 0 {0} {0}\" stroke=\"none\">\n", dimension));
-		result.push_str("\t<rect width=\"100%\" height=\"100%\" fill=\"#FFFFFF\"/>\n");
-		result.push_str("\t<path d=\"");
+		result += &format!(
+			"<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" viewBox=\"0 0 {0} {0}\" stroke=\"none\">\n", dimension);
+		result += "\t<rect width=\"100%\" height=\"100%\" fill=\"#FFFFFF\"/>\n";
+		result += "\t<path d=\"";
 		let mut head: bool = true;
 		for y in -border .. self.size + border {
 			for x in -border .. self.size + border {
@@ -252,14 +252,14 @@ impl QrCode {
 					if head {
 						head = false;
 					} else {
-						result.push_str(" ");
+						result += " ";
 					}
-					result.push_str(&format!("M{},{}h1v1h-1z", x + border, y + border));
+					result += &format!("M{},{}h1v1h-1z", x + border, y + border);
 				}
 			}
 		}
-		result.push_str("\" fill=\"#000000\"/>\n");
-		result.push_str("</svg>\n");
+		result += "\" fill=\"#000000\"/>\n";
+		result += "</svg>\n";
 		result
 	}