test5.lua

print("hello " .. "world")  -->output:hello world
print(0 .. 1)  -->output:01

str1 = string.format("%s-%s","hello","world")
print(str1)  -->output:hello-world

str2 = string.format("%d-%s-%.2f",123,"world",1.21)
print(str2)  -->output:123-world-12.1