Ok, it seem that strtol(pointer, &pointer, 10); or strtol(pointer, &endpointer, 10); give the same result. I read the man page of strtol and the example program use strtol(pointer, &endpointer, 10); for error detection. So no problem with the instruction strtol(pointer, &pointer, 10); if you don’t check for error.
It works now, I just had to fix a couple of bugs, because the program wasn’t reaching the part where triangles are added to the “triangles” vector. Now I just need to make functions for mtllib and usemtl, and add some other features 
I uploaded the code, by the way. Thanks for your help! Now I can import models from Blender.
Good to know that your program run fine now.