Best way to program 8 directional movement?

[TehKyle]

I want to reduce speed on diagonal movement, but I don't know how do code it properly.

Also, how do you deal with Left + Right and Up + Down conflict?
If you code something like

if (L) xFlag= -1;
if (R) xFlag= 1;
if (U) yFlag= -1;
if (D) yFlag= 1;
Move (xFlag, yFlag, framespeed)

You have Right and Down overwriting Left and Up when you press them together.

[Nexus]

Code: [Select]

const float speed = ...;
sf::Vector2f v;

if (left)    v.x -= speed;
if (right)   v.x += speed;

if (up)      v.y -= speed;
if (down)    v.y += speed;

if (v.x != 0.f && v.y != 0.f)
    v /= std::sqrt(2.f);