char is a 1 byte / integer. it is NOT a string, and its not even a unicode compatible character. It can store ascii type letters or small integer values.
con1 cannot ever be "USD" that is 3 letters, 3 bytes, a text string.
you want
#include <string>
string con1;
if (con1 == "USD")
later on you may see old C style code that uses arrays of char as 'strings'. That is very hands-on and not worth talking about today.
now that you know what the problem is, you should see if your compiler was trying to warn you about it and make sense of the words it uses. Learning to read your errors and warnings takes some getting used to.