For some reason IG MetaTrader 4 does not recognize SymbolInfoString(_Symbol,SYMBOL_CURRENCY_BASE); and it returns the Symbol Currency Quote. The work around I use same method for identifying Quote Currency.
Does not work:
string baseCurrency=SymbolInfoString(_Symbol,SYMBOL_CURRENCY_BASE);//Identify base currency
Does work:
string baseCurrency=StringSubstr(_Symbol,0,3);//Identify base currency
string quoteCurrency=StringSubstr(_Symbol,3,3);//Identify quote currency