Why can't Mata code output?

[qing xuan]

I have a file called hellox.ado that contains the following code:

program hellox
version 15
mata: hello()
end
version 15
mata:
void hello()
{
printf("test output\n")
}
end

Then I use the following code to call it in a do-file:

clear all
do hellox.ado

Why doesn't it output "test output"?

[Nick Cox]

Duplicate post. Please follow https://www.statalist.org/forums/for...ta-code-output if interested.