What does execute() return?

Question

In the function-list, it gives execute() as running an ex command, but it does not seem to be returning a string as I expect.

For example, if I run this on a file that has 'abc' in it somewhere:

:echo execute("%s/abc//gen")

Then it answers: "1 match on 1 line". Then if make the following command:

:echo str2nr("1 match on 1 line")

Then it returns the number 1 on the status line. However, finally, if I run this:

:echo str2nr(execute("%s/abc//gen"))

Then it returns 0 on the status line, not 1 as expected. What is going wrong here?

Answer 1

The reason is that the result of execute("%s/abc//gen") is not the same as the string "1 match on 1 line", but "\n1 match on 1 line". When you echo this, it outputs as expected, but with str2nr, the initial newline leads to your unexpected 0 return value.

As is described in :help execute(), you can use split to get a list of lines of the output. So, this should work:

echo str2nr(join(split(execute('%s/abc//gen'), "\n")))