Why doesn't return modify the value of a parameter to a function

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How to modify content of the original variable which is passed by value?

I am building a

Answer 1

FindArea (rArea , rBase , rHeight);

doesn't work like you think it does. In C, parameters are passed by value; that means modifying area inside the function modifies only a local copy of it. You need to assign the return value of the function to the variable:

int FindArea(int w, int h) { return w * h; }

int w, h, area;

// ...
area = findArea(w, h);