fopen64/ fseeko64 and c++ 11

Im writing a code in c++ with codeblocks. I included the flag : " get g++ follow c++ 11.." In the compiler settings to use chrono class, but after i included this flag i couldent compile the program because suddenly the function fopen64 "was not declared in the scope". Just so you know- i can compile the program without the flag. How can i use both fopen64 and chrono class? Is this possible? And if not, is there other precise time measurement class so i can use to mesure microseconds? Thanks!