#include <stdio.h>

#include <stdlib.h>

int main(int argc, char **argv) {

FILE *command;

//command = _popen( "\"C:\\Program Files\\gnuplot\\bin\\gnuplot\"", "w" ); // XP可用，Vista不行

command = _popen( "pgnuplot", "w" ); // XP Vista 皆可

fprintf( command, "a=-1; b=-2; c=3;" );

fprintf( command, "plot a*x*x+b*x+c\n");

fflush( command );

system("PAUSE");

_pclose( command );

return 0;

}