new tasks

Task/Binary_strings/Lua/binary_strings.lua

@@ -0,0 +1,31 @@
+foo = 'foo'             -- Ducktyping foo to be string 'foo'
+bar = 'bar'
+assert (foo == "foo")   -- Comparing string var to string literal
+assert (foo ~= bar)
+str = foo               -- Copy foo contents to str
+if #str == 0 then       -- # operator returns string length
+    print 'str is empty'
+end
+str=str..string.char(50)-- Char concatenated with .. operator
+substr = str:sub(1,3)   -- Extract substring from index 1 to 3, inclusively
+
+str = "string string string string"
+-- This function will replace all occurances of 'replaced' in a string with 'replacement'
+function replaceAll(str,replaced,replacement)
+    local function sub (a,b)
+        if b > a then
+            return str:sub(a,b)
+        end
+        return nil
+    end
+    a,b = str:find(replaced)
+    while a do
+        str = str:sub(1,a-1) .. replacement .. str:sub(b+1,#str)
+        a,b = str:find(replaced)
+    end
+    return str
+end
+str = replaceAll (str, 'ing', 'ong')
+print (str)
+
+str = foo .. bar -- Strings concatenate with .. operator