Not able to use bitcoin/bitcoin.hpp the libbitcoin library seems to have been installed just fine. 
but the following code can't seem to include bitcoin/bitcoin.hpp

#include&lt;bitcoin/bitcoin.hpp&gt;
#include&lt;iostream&gt;
using namespace bc;
int main() {
    block_type blk = genesis_block();
    std::cout&lt;&lt;encode_hex(hash_block_header(blk.header))&lt;&lt;std::endl;
    return 0;
}


Error: 

g++ -o test test.cpp $(pkg-config --cflags --libs libbitcoin)
test.cpp: In function ‘int main()’:
test.cpp:5:5: error: ‘block_type’ was not declared in this scope
     block_type blk = genesis_block();
     ^~~~~~~~~~
test.cpp:5:5: note: suggested alternative: ‘clock_t’
     block_type blk = genesis_block();
     ^~~~~~~~~~
     clock_t
test.cpp:6:45: error: ‘blk’ was not declared in this scope
     std::cout&lt;&lt;encode_hex(hash_block_header(blk.header))&lt;&lt;std::endl;
                                             ^~~
test.cpp:6:45: note: suggested alternative: ‘brk’
     std::cout&lt;&lt;encode_hex(hash_block_header(blk.header))&lt;&lt;std::endl;
                                             ^~~
                                             brk
test.cpp:6:27: error: ‘hash_block_header’ was not declared in this scope
     std::cout&lt;&lt;encode_hex(hash_block_header(blk.header))&lt;&lt;std::endl;
                           ^~~~~~~~~~~~~~~~~
test.cpp:6:16: error: ‘encode_hex’ was not declared in this scope
     std::cout&lt;&lt;encode_hex(hash_block_header(blk.header))&lt;&lt;std::endl;
                ^~~~~~~~~~
Try adding the -std=c++11 flag. 

I had the same problem and the following worked for me:

g++ -std=c++11 -o test test.cpp $(pkg-config --cflags --libs libbitcoin)