You can use:
GLfloat coordinates[8] = {1.0f, ..., 0.0f};
but this is a compile-time initialisation - you can't use that method in the current standard to re-initialise (although I think there are ways to do it in the upcoming standard, which may not immediately help you).
The other two ways that spring to mind are to blat the contents if they're fixed:
GLfloat base_coordinates[8] = {1.0f, ..., 0.0f};
GLfloat coordinates[8];
:
memcpy (coordinates, base_coordinates, sizeof (coordinates));
or provide a function that looks like your initialisation code anyway:
void setCoords (float *p0, float p1, ..., float p8) {
p0[0] = p1; p0[1] = p2; p0[2] = p3; p0[3] = p4;
p0[4] = p5; p0[5] = p6; p0[6] = p7; p0[7] = p8;
}
:
setCoords (coordinates, 1.0f, ..., 0.0f);
keeping in mind those ellipses (...) are placeholders, not things to literally insert in the code.