implement recursive and iterative functions to reverse a string

reverse_string.c

@@ -24,10 +24,24 @@ Note that strings that are stored on heap or stack are provided - they can be di
 
 // TODO: the recursive implementation
 void reverse_string_recursive(char* str, int start, int end) {
+    if(start >= end) {
         return;
+    }
+
+    char temp = str[start];
+    str[start] = str[end];
+    str[end] = temp;
+    start++;
+    end--;
+    reverse_string_recursive(str, start, end);
 }
 
-// TODO: the iterative implementation
 void reverse_string_iterative(char* str, int start, int end) {
-    return;
+    while(start < end) {
+        char temp = str[start];
+        str[start] = str[end];
+        str[end] = temp;
+        start++;
+        end--;
+    }
 }