infile_name = "C:/work_files/libigl/tutorial/shared/male1.mesh"
outfile_name = "C:/work_files/libigl/tutorial/shared/male1.mesh.o"
string_to_add = " 0"
with open(infile_name, 'r') as f:
file_lines = [''.join([x.strip(), string_to_add, '\n']) for x in f.readlines()]
with open(outfile_name, 'w') as f:
f.writelines(file_lines)