Save data in .dat file

[reald]

Hello I have this in my program

SKIP;
for(k = 0, pc_new = pc; k < 6; k++)
{
for(n = 0; n < header1.npart[k]; n++)
{
fread(&P[pc_new].Pos[0], sizeof(float), 3, fd);
pc_new++;
}
}
SKIP

and i want to save the three components of P[pc_new].Pos[0] in a dat file (for all those values of pc_new)
How can I do that??