Why we cannot compare two same type of structure?

Question

Two tables from two different databases are there . both having same structure but different data . how to compare these two tables ?

Answer 1

As far as I know, In C language comparison operator == works with predefined datatypes.
Structure is a user defined data type that's why == does not work.
Assume one structure is defined named as "A".
Now I created two variables of structure A such as var1 and var2
Better to use memory comparison memcmp(&var1, &var2, sizeof(A)) to compare user defined data types.