gnuplot - Gnuplot_i date/time formatting error -

i using gnuplot_i library (version 2.11) in c -code generates png -pictures. time/date column not format correctly.

source:

gnuplot_ctrl * h0 ; h0 = gnuplot_init() ; gnuplot_set_xlabel(h0, "header") ; gnuplot_cmd(h0, "set terminal png size 800,480") ; gnuplot_cmd(h0, "set output 'picture.png'") ; gnuplot_cmd(h0, "set xdata time") ; gnuplot_cmd(h0, "set timefmt '%y-%m-%d-%h:%m'") ; gnuplot_cmd(h0, "set format x '%h:%m' ") ; gnuplot_cmd(h0, "set grid") ; gnuplot_cmd(h0, "plot \"datafile.tsv\" u 1:2 w l t \"title\" "); gnuplot_close(h0) ; 

datafile.tsv contains:

2017-09-08-18:03    12.69  2017-09-08-18:04    12.69  2017-09-08-18:05    12.69  2017-09-08-18:06    12.69 

...

unfortunately command gnuplot_cmd(h0, "show timefmt"); produces error:

warning: empty x range [1.48323e+09:1.48323e+09], adjusting [1.4684e+09:1.49806e+09] default format reading time data "%y-no such file or directory-0- %h:%m"

why %m formatted "no such file or directory" , %d "0" ?

i've read gnuplot_i manual, , command gnuplot_cmd has parameter cmd should formatted in printf function. time format interpreted format string because of '%' characters. should use instead like

gnuplot_cmd(h0, "set timefmt \"%%y-%%m-%%d-%%h:%%m\""); gnuplot_cmd(h0, "set format x \"%%h:%%m\"") ;