Fix from_str in stdlib, add concat_strings

examples/hello_world.reid

@@ -3,14 +3,20 @@ import std::from_str;
 import std::add_char;
 import std::set_char;
 import std::free_string;
+import std::new_string;
 import std::add_num_to_str;
+import std::concat_strings;
 
 fn main() -> i32 {
-    let mut test = from_str("hello world");
+    let mut test = from_str("hello");
+    let mut other = from_str(" world");
+
+    concat_strings(&mut test, &other);
 
     add_char(&mut test, '!');
-    set_char(&mut test, 'B', 0);
-    add_num_to_str(&mut test, 1234);
+    add_char(&mut test, '\n');
+
+    add_num_to_str(&mut test, 175);
     
     print(&test);
 

reid/lib/std.reid

@@ -39,14 +39,15 @@ pub fn new_string() -> String {
 
 pub fn from_str(str: *char) -> String {
     let length = str_length(str);
-    let cloned = malloc(length as u64) as *char;
-    copy_bits(str, cloned, length as u64);
-    return String {
-        inner: cloned,
-        length: length -1,
+    let mut new = new_string();
+    let static = String {
+        inner: str,
+        length: length - 1,
         max_length: length,
         must_be_freed: false,
     };
+    concat_strings(&mut new, &static);
+    return new;
 }
 
 pub fn add_char(string: &mut String, c: char) {
@@ -63,7 +64,7 @@ pub fn add_char(string: &mut String, c: char) {
     }
 
     (*string).inner[(*string).length] = c;
-    (((*string).inner) as *u8)[((*string).length + 1)] = 0;
+    (((*string).inner) as *u8)[(*string).length + 1] = 0;
     (*string).length = (*string).length + 1;
 }
 
@@ -124,4 +125,10 @@ pub fn abs(f: f32) -> f32 {
         return f * (0.0 - 1.0);
     }
     return f;
-}
+}
+
+pub fn concat_strings(destination: &mut String, source: &String) {
+    for i in 0 .. (str_length((*source).inner) - 1) {
+        add_char(destination, (*source).inner[i]);
+    }
+}