Save specific data from a rosbag into an C++ array variable.

Hello, Currently I am working on a project and we need to extract msgs from a topic inside a rosbag file. Our first idea was to save all the msgs of the topic into a .txt and after that process that data with C++ but there is too much data and is not the optimal solution. (rostopic echo /topic > data.txt) My question is the next: How can I extract some specific msg for an specific timestamp in C++ and save those msg into an array? After that i would like to use that array for my C++ code. PD: I have checked rosbag c++ API but I didn´t find how to do that. Thanks for your help