how can i get `print_output`, use `capture.output` and result is NULL.

[wydty]

Hi jensen:

how can i get print_output, use capture.output and result is NULL.

> capture.output(  
+   calculate_hairpin('CCCCCATCCGATCAGGGGG', print_output=T)
+ ) -> out
Calculated thermodynamical parameters for dimer:	19	dS = -108.107	dH = -36300	dG = -2770.52	t = 62.6275
SEQ	/////---------\\\\\
STR	CCCCCATCCGATCAGGGGG

> cat(out)
NULL

[wydty]

Possible reference,
https://github.com/coatless-r-n-d/r-c-api-remap-printf
https://stackoverflow.com/questions/48312317/is-it-possible-to-grab-scrape-the-call-output-of-c-printf-within-r-or