Question

Hi I am trying to write a function which reads data from a file and then saves it in memory.
This memory will need a x and a y value to be identified. It may not be linear, there can be big jumps between the different x and y values and the amount of values are unknown which excludes the use of an multi-dimensional array.

I wanted to use std::map since it does what I need, but it does not support multiple key values. What else could I use to store the data or is there a way to merge the X and Y values so that it will be able to be used in a map container?

Answer 1

Make a pair of the x and y values, and use that as the key:

std::map<std::pair<int, int>, whatever>

Note that as it stands, this will treat the x values as more significant than the y values if you traverse the map in order. If you want the y values to be more significant, you’d want to put them first in the pair.