diff --git a/Source/Engine/Core/Types/String.cpp b/Source/Engine/Core/Types/String.cpp
index 103dbaf00..1cd9fde88 100644
--- a/Source/Engine/Core/Types/String.cpp
+++ b/Source/Engine/Core/Types/String.cpp
@@ -21,6 +21,84 @@ String::String(const StringAnsiView& str)
     Set(str.Get(), str.Length());
 }
 
+void String::Set(const Char* chars, int32 length)
+{
+    if (length != _length)
+    {
+        ASSERT(length >= 0);
+        Platform::Free(_data);
+        if (length != 0)
+        {
+            _data = (Char*)Platform::Allocate((length + 1) * sizeof(Char), 16);
+            _data[length] = 0;
+        }
+        else
+        {
+            _data = nullptr;
+        }
+        _length = length;
+    }
+
+    Platform::MemoryCopy(_data, chars, length * sizeof(Char));
+}
+
+void String::Set(const char* chars, int32 length)
+{
+    if (length != _length)
+    {
+        Platform::Free(_data);
+        if (length != 0)
+        {
+            _data = (Char*)Platform::Allocate((length + 1) * sizeof(Char), 16);
+            _data[length] = 0;
+        }
+        else
+        {
+            _data = nullptr;
+        }
+        _length = length;
+    }
+
+    if (chars)
+        StringUtils::ConvertANSI2UTF16(chars, _data, length);
+}
+
+void String::Append(const Char* chars, int32 count)
+{
+    if (count == 0)
+        return;
+
+    const auto oldData = _data;
+    const auto oldLength = _length;
+
+    _length = oldLength + count;
+    _data = (Char*)Platform::Allocate((_length + 1) * sizeof(Char), 16);
+
+    Platform::MemoryCopy(_data, oldData, oldLength * sizeof(Char));
+    Platform::MemoryCopy(_data + oldLength, chars, count * sizeof(Char));
+    _data[_length] = 0;
+
+    Platform::Free(oldData);
+}
+
+void String::Append(const char* chars, int32 count)
+{
+    if (count == 0)
+        return;
+
+    const auto oldData = _data;
+    const auto oldLength = _length;
+
+    _length = oldLength + count;
+    _data = (Char*)Platform::Allocate((_length + 1) * sizeof(Char), 16);
+
+    Platform::MemoryCopy(_data, oldData, oldLength * sizeof(Char));
+    StringUtils::ConvertANSI2UTF16(chars, _data + oldLength, count * sizeof(Char));
+    _data[_length] = 0;
+
+    Platform::Free(oldData);
+}
+
 String& String::operator+=(const StringView& str)
 {
     Append(str.Get(), str.Length());
@@ -149,6 +227,22 @@ bool String::EndsWith(const StringView& suffix, StringSearchCase searchCase) con
     return !StringUtils::Compare(&(*this)[Length() - suffix.Length()], *suffix);
 }
 
+String String::ToLower() const
+{
+    String result(*this);
+    for (int32 i = 0; i < result.Length(); i++)
+        result[i] = StringUtils::ToLower(result[i]);
+    return result;
+}
+
+String String::ToUpper() const
+{
+    String result(*this);
+    for (int32 i = 0; i < result.Length(); i++)
+        result[i] = StringUtils::ToUpper(result[i]);
+    return result;
+}
+
 void String::TrimToNullTerminator()
 {
     const int32 length = _length;
diff --git a/Source/Engine/Core/Types/String.h b/Source/Engine/Core/Types/String.h
index cf21a1236..c42d82dde 100644
--- a/Source/Engine/Core/Types/String.h
+++ b/Source/Engine/Core/Types/String.h
@@ -617,100 +617,30 @@ public:
     /// <summary>
     /// Sets an array of characters to the string.
     /// </summary>
-    /// <param name="chars">The pointer to the start of an array of characters to set. This array need not be null-terminated, and null characters are not treated specially.</param>
+    /// <param name="chars">The pointer to the start of an array of characters to set (UTF-16). This array need not be null-terminated, and null characters are not treated specially.</param>
     /// <param name="length">The number of characters to assign.</param>
-    void Set(const Char* chars, int32 length)
-    {
-        if (length != _length)
-        {
-            ASSERT(length >= 0);
-            Platform::Free(_data);
-            if (length != 0)
-            {
-                _data = (Char*)Platform::Allocate((length + 1) * sizeof(Char), 16);
-                _data[length] = 0;
-            }
-            else
-            {
-                _data = nullptr;
-            }
-            _length = length;
-        }
-
-        Platform::MemoryCopy(_data, chars, length * sizeof(Char));
-    }
+    void Set(const Char* chars, int32 length);
 
     /// <summary>
     /// Sets an array of characters to the string.
     /// </summary>
-    /// <param name="chars">The pointer to the start of an array of characters to set. This array need not be null-terminated, and null characters are not treated specially.</param>
+    /// <param name="chars">The pointer to the start of an array of characters to set (ANSI). This array need not be null-terminated, and null characters are not treated specially.</param>
     /// <param name="length">The number of characters to assign.</param>
-    void Set(const char* chars, int32 length)
-    {
-        if (length != _length)
-        {
-            Platform::Free(_data);
-            if (length != 0)
-            {
-                _data = (Char*)Platform::Allocate((length + 1) * sizeof(Char), 16);
-                _data[length] = 0;
-            }
-            else
-            {
-                _data = nullptr;
-            }
-            _length = length;
-        }
-
-        if (chars)
-            StringUtils::ConvertANSI2UTF16(chars, _data, length);
-    }
+    void Set(const char* chars, int32 length);
 
     /// <summary>
     /// Appends an array of characters to the string.
     /// </summary>
     /// <param name="chars">The array of characters to append. It does not need be null-terminated, and null characters are not treated specially.</param>
     /// <param name="count">The number of characters to append.</param>
-    void Append(const Char* chars, int32 count)
-    {
-        if (count == 0)
-            return;
-
-        const auto oldData = _data;
-        const auto oldLength = _length;
-
-        _length = oldLength + count;
-        _data = (Char*)Platform::Allocate((_length + 1) * sizeof(Char), 16);
-
-        Platform::MemoryCopy(_data, oldData, oldLength * sizeof(Char));
-        Platform::MemoryCopy(_data + oldLength, chars, count * sizeof(Char));
-        _data[_length] = 0;
-
-        Platform::Free(oldData);
-    }
+    void Append(const Char* chars, int32 count);
 
     /// <summary>
     /// Appends an array of characters to the string.
     /// </summary>
     /// <param name="chars">The array of characters to append. It does not need be null-terminated, and null characters are not treated specially.</param>
     /// <param name="count">The number of characters to append.</param>
-    void Append(const char* chars, int32 count)
-    {
-        if (count == 0)
-            return;
-
-        const auto oldData = _data;
-        const auto oldLength = _length;
-
-        _length = oldLength + count;
-        _data = (Char*)Platform::Allocate((_length + 1) * sizeof(Char), 16);
-
-        Platform::MemoryCopy(_data, oldData, oldLength * sizeof(Char));
-        StringUtils::ConvertANSI2UTF16(chars, _data + oldLength, count * sizeof(Char));
-        _data[_length] = 0;
-
-        Platform::Free(oldData);
-    }
+    void Append(const char* chars, int32 count);
 
     /// <summary>
     /// Appends the specified text to this string.
@@ -990,25 +920,13 @@ public:
     /// Converts all uppercase characters to lowercase.
     /// </summary>
     /// <returns>The lowercase string.</returns>
-    String ToLower() const
-    {
-        String result(*this);
-        for (int32 i = 0; i < result.Length(); i++)
-            result[i] = StringUtils::ToLower(result[i]);
-        return result;
-    }
+    String ToLower() const;
 
     /// <summary>
     /// Converts all lowercase characters to uppercase.
     /// </summary>
     /// <returns>The uppercase string.</returns>
-    String ToUpper() const
-    {
-        String result(*this);
-        for (int32 i = 0; i < result.Length(); i++)
-            result[i] = StringUtils::ToUpper(result[i]);
-        return result;
-    }
+    String ToUpper() const;
 
     /// <summary>
     /// Gets the left most given number of characters.