Calculating velocity using consistent speed in basic C++ engine - c++

Question

What I'm trying to achieve is a sprite moving to another sprite in a 2D environment. I started with the basic Mx = Ax - Bx deal. But I noticed that the closer to the target the sprite gets, the more it slows down. So I tried to create a percentage/ratio based on the velocity then each x and y gets their percent of a speed allowance, however, it's acting very strangely and only seems to work if Mx and My are positive
Here's the code extract:
ballX = ball->GetX();
ballY = ball->GetY();
targX = target->GetX();
targY = target->GetY();
ballVx = (targX - ballX);
ballVy = (targY - ballY);
percentComp = (100 / (ballVx + ballVy));
ballVx = (ballVx * percentComp)/10000;
ballVy = (ballVy * percentComp)/10000;
The /10000 is to slow the sprites movement

Answer 1

Assuming you want the sprite to move at a constant speed, you can do a linear fade on both the X and Y position, like this:
#include <stdio.h>
int main(int, char **)
{
float startX = 10.0f, startY = 20.0f;
float endX = 35.0f, endY = -2.5f;
int numSteps = 20;
for (int i=0; i<numSteps; i++)
{
float percentDone = ((float)i)/(numSteps-1);
float curX = (startX*(1.0f-percentDone)) + (endX*percentDone);
float curY = (startY*(1.0f-percentDone)) + (endY*percentDone);
printf("Step %i: percentDone=%f curX=%f curY=%f\n", i, percentDone, curX, curY);
}
return 0;
}

Answer 2

Thanks for the responses, I got it working now but normalising the vectors instead of the whole percent thing, here's what I have now:
ballX = ball->GetX();
ballY = ball->GetY();
targX = target->GetX();
targY = target->GetY();
ballVx = (targX - ballX);
ballVy = (targY - ballY);
vectLength = sqrt((ballVx*ballVx) + (ballVy*ballVy));
ballVx = (ballVx / vectLength)/10;
ballVy = (ballVy / vectLength)/10;