Differently from most countries, Brazilians are not used to seeing foreigner currency bills; even the American dollar and the euro have limited course; traveller checks are also restricted (usually, foreigners must exchange the currency before paying their bills, in Reais). Brazilians have no authorization to have bank accounts in dollar; Brazilian firms (including hotels) must provide invoices and receipts in Reais.
Currency exchange businesses exist in all major cities. "Casas de Cambio" are establishments that deal only with currencies; a few branches of a few banks also trade currencies, but not at an advantageous rate to the customer.
Brazilian banks have developed an efficient Information Technology infrastructure; holders of major credit cards can use Brazilian ATMs to access their accounts and withdraw cash (other transactions are limited).
We were in cape verde 3 years ago and the atms were a complete nightmare with atleast 1 hr wait and then sometimes the machine ran out. most places took dollars but we changed our money in the hotel mindelo hotel in the square, (this was the island where the cruise liners docked. on the ilsland of sal which was much more comercial we found we could use euro dollars sterling infact as long as we purchased something! TAKE CARE if you are out at night in san vincente.
The Cape verde currency is the Cape Verde Escudo, which is pegged at 110 to the Euro. Cape Verdes do not accept credit cards.