Why do I get those strange spaces?

```
echo "hello world" | awk 'BEGIN{FS=""} {$1=toupper($1); printf "%s\n", $0}'

```

I get the same result with the simpler way.

```
echo "hello world" | awk 'BEGIN{FS=""} {$1=toupper($1); print}'

```

Output:

```
H e l l o   w o r l d

```