Default variable value

Question

If I don\'t assign a value to a variable when I declare it, does it default to zero or just whatever was previously in the memory?

e.g.

float x;
         


        

Answer 1

I think it's undefined. I think some compilers, when compiling in debug mode, initialize it to zero. But it's also ok to have it be whatever was already there in memory. Basically - don't rely on either behavior.

UPDATE: As per the comments - global variables will be zero-initialized. Local variables will be whatever.

To answer your second question:

Thanks - following on from this then, is there a shortcut to assign zero to all of the following?: float x1, x2, x3, x4, x5, y1, y2, y3, y4, y5

You could do

float x[5] = {0,0,0,0,0}; float y[5] = {0,0,0,0,0};

and use x[0] instead of x1.