diff --git a/QRCodeLibrary/DataBlocks.cpp b/QRCodeLibrary/DataBlocks.cpp
index d12c019..e5346b0 100644
--- a/QRCodeLibrary/DataBlocks.cpp
+++ b/QRCodeLibrary/DataBlocks.cpp
@@ -3,7 +3,7 @@
 #include "DataBlocks.hpp"
 #include "Tables.hpp"
 
-vector<unsigned char>& DataBlocks::compose_data_and_EC_blocks()
+vector<unsigned char>& DataBlocks::compose_joined_data_and_EC_blocks()
 {
 	vector<pair<unsigned, unsigned>>data_block_sizes;
 
@@ -14,6 +14,8 @@ vector<unsigned char>& DataBlocks::compose_data_and_EC_blocks()
 	for (unsigned i = 0; i < data_block_sizes.size(); i++)
 		compose_EC_bytes(EC_blocks[i], e_data.cbegin() + data_block_sizes[i].second, EC_bytes_number, data_block_sizes[i].first);
 
+	join_data_and_EC_blocks(data, e_data, data_block_sizes, EC_blocks);
+
 	return data;
 }
 
@@ -52,3 +54,25 @@ void DataBlocks::compose_EC_bytes(vector<unsigned char>& res, const vector<unsig
 		}
 	}
 }
+
+unsigned get_db_byte_index(unsigned block_index, unsigned byte_index, const vector<pair<unsigned, unsigned>>& db_sizes) {
+	return db_sizes[block_index].second + byte_index;
+}
+
+void DataBlocks::join_data_and_EC_blocks(vector<unsigned char>& res, const vector<unsigned char>& e_data, const vector<pair<unsigned, unsigned>>& db_sizes, const vector<vector<unsigned char>>& ec_codes)
+{
+	if (ec_codes.size())
+		res.reserve(e_data.size() + ec_codes.at(0).size() * ec_codes.size());
+	else
+		res.reserve(e_data.size());
+
+	for (unsigned i = 0; i < db_sizes[db_sizes.size() - 1].first; i++)
+		for (unsigned j = 0; j < db_sizes.size(); j++)
+			if (i < db_sizes[j].first)
+				res.push_back(e_data[get_db_byte_index(j, i, db_sizes)]);
+
+	if (ec_codes.size())
+		for (unsigned i = 0; i < ec_codes.at(0).size(); i++)
+			for (unsigned j = 0; j < ec_codes.size(); j++)
+				res.push_back(ec_codes[j][i]);
+}
diff --git a/QRCodeLibrary/DataBlocks.hpp b/QRCodeLibrary/DataBlocks.hpp
index a46f82c..3bfcc7f 100644
--- a/QRCodeLibrary/DataBlocks.hpp
+++ b/QRCodeLibrary/DataBlocks.hpp
@@ -12,11 +12,11 @@ class DataBlocks
 public:
 	DataBlocks(const vector<unsigned char>& e_data_, CorrectionLevel corr_lvl_, unsigned char version_) : e_data{ e_data_ }, corr_lvl{ corr_lvl_ }, version{ version_ } {};
 
-	vector<unsigned char>& compose_data_and_EC_blocks();
+	vector<unsigned char>& compose_joined_data_and_EC_blocks();
 
 	static void divide_to_blocks(vector<pair<unsigned, unsigned>>& db_sizes, unsigned data_size, unsigned db_number);
-
 	static void compose_EC_bytes(vector<unsigned char>& res, const vector<unsigned char>::const_iterator& src, unsigned corr_bytes_num, unsigned db_size);
+	static void join_data_and_EC_blocks(vector<unsigned char>&res, const vector<unsigned char>& e_data, const vector<pair<unsigned, unsigned>>& db_sizes, const vector<vector<unsigned char>>& ec_codes);
 
 private:
 	const vector<unsigned char>& e_data;
diff --git a/QRCodeLibrary/QRCode.cpp b/QRCodeLibrary/QRCode.cpp
index bfd0a9c..a1de701 100644
--- a/QRCodeLibrary/QRCode.cpp
+++ b/QRCodeLibrary/QRCode.cpp
@@ -15,5 +15,5 @@ QRCode::QRCode(string& input_, CorrectionLevel corr_lvl_, QRCodeMethod method_,
 	const BitArray& encoded_data = encoder.encode();
 
 	DataBlocks data_blocks(encoded_data.v, corr_lvl, version);
-	vector<unsigned char>& blocked_data = data_blocks.compose_data_and_EC_blocks();
+	vector<unsigned char>& final_message = data_blocks.compose_joined_data_and_EC_blocks();
 }
diff --git a/tests/DataBlocks_test.cpp b/tests/DataBlocks_test.cpp
index bce29e8..3f415bc 100644
--- a/tests/DataBlocks_test.cpp
+++ b/tests/DataBlocks_test.cpp
@@ -7,23 +7,76 @@
 
 TEST(DataBlocksTests, ComposesSizesOfDatablocks) {
 	vector<pair<unsigned, unsigned>> db_s;
-	vector<pair<unsigned, unsigned>> res{ {36, 0}, {36, 36}, {36, 72}, {37, 108}, {37, 145} };
 
 	DataBlocks::divide_to_blocks(db_s, 182, 5);
 
+	const vector<pair<unsigned, unsigned>> res{ {36, 0}, {36, 36}, {36, 72}, {37, 108}, {37, 145} };
 	EXPECT_EQ(db_s, res);
 }
 
 TEST(DataBlocksTests, GeneratesECBytes) {
-	vector<unsigned char> input{ 64, 196, 132, 84, 196, 196, 242, 194, 4, 132, 20, 37, 34, 16, 236, 17 };
+	const vector<unsigned char> input{ 64, 196, 132, 84, 196, 196, 242, 194, 4, 132, 20, 37, 34, 16, 236, 17 };
 	vector<unsigned char> tmp;
-	vector<unsigned char> res{ 16, 85, 12, 231, 54, 54, 140, 70, 118, 84, 10, 174, 235, 197, 99, 218, 12, 254, 246, 4, 190, 56, 39, 217, 115, 189, 193, 24 };
 
 	DataBlocks::compose_EC_bytes(tmp, input.cbegin(), 28, 16);
 
+	const vector<unsigned char> res{ 16, 85, 12, 231, 54, 54, 140, 70, 118, 84, 10, 174, 235, 197, 99, 218, 12, 254, 246, 4, 190, 56, 39, 217, 115, 189, 193, 24 };
 	EXPECT_EQ(tmp, res);
 }
 
-TEST(DataBlocksTests, ComposesDataAndECBlocks) {
-	DataBlocks db(vector<unsigned char>(182), CorrectionLevel::M, 8);
+TEST(DataBlocksTests, JoinsDataAndECBlocks) {
+	vector<unsigned char>joined;
+	const vector<unsigned char>e_data{
+		67, 85, 70, 134, 87, 38, 85, 194, 119, 50, 6, 18, 6, 103, 38,
+		246, 246, 66, 7, 118, 134, 242, 7, 38, 86, 22, 198, 199, 146, 6,
+		182, 230, 247, 119, 50, 7, 118, 134, 87, 38, 82, 6, 134, 151, 50, 7,
+		70, 247, 118, 86, 194, 6, 151, 50, 16, 236, 17, 236, 17, 236, 17, 236
+	};
+	const vector<pair<unsigned, unsigned>> d_b_sizes{ {15, 0}, {15, 15}, {16, 30}, {16, 46} };
+	const vector<vector<unsigned char>> EC_blocks{
+		{ 213, 199, 11, 45, 115, 247, 241, 223, 229, 248, 154, 117, 154, 111, 86, 161, 111, 39 },
+		{ 87, 204, 96, 60, 202, 182, 124, 157, 200, 134, 27, 129, 209, 17, 163, 163, 120, 133 },
+		{ 148, 116, 177, 212, 76, 133, 75, 242, 238, 76, 195, 230, 189, 10, 108, 240, 192, 141 },
+		{ 235, 159, 5, 173, 24, 147, 59, 33, 106, 40, 255, 172, 82, 2, 131, 32, 178, 236 }
+	};
+
+	DataBlocks::join_data_and_EC_blocks(joined, e_data, d_b_sizes, EC_blocks);
+
+	const vector<unsigned char>res{
+		67, 246, 182, 70, 85, 246, 230, 247, 70, 66, 247, 118, 134, 7, 119,
+		86, 87, 118, 50, 194, 38, 134, 7, 6, 85, 242, 118, 151, 194, 7,
+		134, 50, 119, 38, 87, 16, 50, 86, 38, 236, 6, 22, 82, 17, 18,
+		198, 6, 236, 6, 199, 134, 17, 103, 146, 151, 236, 38, 6, 50, 17,
+		7, 236, 213, 87, 148, 235, 199, 204, 116, 159, 11, 96, 177, 5, 45,
+		60, 212, 173, 115, 202, 76, 24, 247, 182, 133, 147, 241, 124, 75, 59,
+		223, 157, 242, 33, 229, 200, 238, 106, 248, 134, 76, 40, 154, 27, 195,
+		255, 117, 129, 230, 172, 154, 209, 189, 82, 111, 17, 10, 2, 86, 163,
+		108, 131, 161, 163, 240, 32, 111, 120, 192, 178, 39, 133, 141, 236
+	};
+	EXPECT_EQ(joined, res);
+}
+
+TEST(DataBlocksTests, ComposesJoinedDataAndECBlocks) {
+	const vector<unsigned char>e_data{
+		67, 85, 70, 134, 87, 38, 85, 194, 119, 50, 6, 18, 6, 103, 38,
+		246, 246, 66, 7, 118, 134, 242, 7, 38, 86, 22, 198, 199, 146, 6,
+		182, 230, 247, 119, 50, 7, 118, 134, 87, 38, 82, 6, 134, 151, 50, 7,
+		70, 247, 118, 86, 194, 6, 151, 50, 16, 236, 17, 236, 17, 236, 17, 236
+	};
+
+	DataBlocks db(e_data, CorrectionLevel::Q, 4);
+
+	const vector<unsigned char> joined{
+		67, 246, 182, 70, 85, 246, 230, 247, 70, 66, 247, 118, 134, 7, 119,
+		86, 87, 118, 50, 194, 38, 134, 7, 6, 85, 242, 118, 151, 194, 7,
+		134, 50, 119, 38, 87, 16, 50, 86, 38, 236, 6, 22, 82, 17, 18,
+		198, 6, 236, 6, 199, 134, 17, 103, 146, 151, 236, 38, 6, 50, 17,
+		7, 236, 213, 87, 148, 235, 199, 204, 116, 159, 11, 96, 177, 5, 45,
+		60, 212, 173, 115, 202, 76, 24, 247, 182, 133, 147, 241, 124, 75, 59,
+		223, 157, 242, 33, 229, 200, 238, 106, 248, 134, 76, 40, 154, 27, 195,
+		255, 117, 129, 230, 172, 154, 209, 189, 82, 111, 17, 10, 2, 86, 163,
+		108, 131, 161, 163, 240, 32, 111, 120, 192, 178, 39, 133, 141, 236
+	};
+
+	EXPECT_EQ(db.compose_joined_data_and_EC_blocks(), joined);
 }
\ No newline at end of file