str = "hello_+asdf2312+887441a+asdf"
table = {}
string.gsub(str, "([%w_]+)",

function(w)

table.insert(table,w)

end
end

str = "hello,john"
s = string.gsub(str, "john", "james")
s ==>"hello,james"

str = "hello,john"
start, end = string.find(str, "hello")
start ==>1
end ==>5

fn_flag = string.find(filename, "\\")

if fn_flag then

dest_filename = string.match(filename, ".+\\([^\\]*%.%w+)$")
end

fn_flag = string.find(filename, "/")

if fn_flag then

dest_filename = string.match(filename, ".+/([^/]*%.%w+)$")
end

str = " helloa,ni hao (asdfasdf) "
newstr = string.gsub(str,"%b()","")

newstr = string.gsub(newstr, "^%s*(.-)%s*$", "%1")

print(newstr)---->helloa,ni hao