I have been giving food but not money, as I had heard that giving money is not recommended by people who work with the homeless.
After reading this thread I decided to google 'What do homelessness charities say about giving food to beggars?' and 'What do homelessness charities say about giving money to beggars?'
The consensus among homelessness charities seems to be that giving money to beggars is not helpful. This is from a 2017 Financial Times article:
//Thames Reach, which supports homeless people and rough sleepers in London through its Street Rescue service and in hostels, is adamant that people should not give cash to beggars. It cites “overwhelming evidence” that people who beg on the streets in England do so to buy hard drugs, particularly crack cocaine and heroin, and super-strength beers and ciders; it estimates that 80 per cent of people begging do so to support a drug habit.
Thames Reach said its motive for launching a campaign over the issue, Killing With Kindness, was that “we were losing people… from hostels, who begged during the day and would wind up overdosing,” it said.
Of people arrested for begging in 2014, fewer than a fifth were legally defined as homeless. In Belfast, of the 146 people arrested in three months in 2015, 142 had an address. It is not the case, as beggars sometimes claim, that they need money to get into a shelter for the night. Hostels are not “pay for entry”: the funding comes from housing benefit which homelessness charities and agencies, often including the hostel itself, can help to access.//
giving-evidence.com/2017/04/20/homeless/
On the other hand, a majority of homelessness charities seem to be OK with people giving food. One letter from a formerly homeless person in Pavement magazine says it would be better not to.
I think I will continue to offer food (the offer is not always accepted), and to give to homelessness charities such as Centrepoint and the Salvation Army.