Where the error ? (!=) (<>)

[sdvcn]

dstring key = "<"d;
dstring str = "<盗墓笔记>"d;

        for(size_t i;i<str.length;)
        {
                bool bh = true;

                foreach(dchar kv;key)
                {
                        dchar t = cast(dchar)tstr[i++]; // 0x3c
                        dchar ta = 0x3c;
                        //if(str[i++] != kv)           //kv : 0x3c
                        //if(t == ta)                // Should return true
                        //if(t <> ta)                // Should return false
                        if(t != ta)                // Should return false
                        {
                                // All returns true ?????****
                                bh = false;
                                i += key.length;
                                break;
                        };
                }
        }

"if(t <> ta)" No right to judge
"if(t != ta)" No right to judge