Not sure why my code result in different graphics

So I have done a piece of code that is supposed to make two equal graphics, just by using different methods to do so. However, end result doesnt seem to go as planned. Can anyone see what is wrong here? How can I fix it?

x = -pi : pi/500 : pi;
for i = -pi:pi/500:pi
    if (x > 0)
        y = sin(x).^2 + (1+x)./(1+exp(x));
    else
        y = (1+x.^2).^(1.0/3.0);
    end
end

figure
plot(x,y);
grid on; 
hold on;
y = ((1+x.^2).^(1.0/3.0)).*(x<=0) + (sin(x).^2 + (1+x)./(1+exp(x))).*(x>0);
plot(x,y);

Answer 1

[Bhaskar R]

You have made for loop mistake and indexing in your code, correct one is

x = -pi : pi/500 : pi;
y =zeros(1, length(x));    % initialize legth of y
for i = 1:length(y)        % you gave x sequence over instead of indexing sequence 
    if (x(i) > 0)
        y(i) = sin(x(i)).^2 + (1+x(i))./(1+exp(x(i)));
    else
        y(i) = (1+x(i).^2).^(1.0/3.0);
    end
end
figure
plot(x,y);
grid on; 
hold on;
y = ((1+x.^2).^(1.0/3.0)).*(x<=0) + (sin(x).^2 + (1+x)./(1+exp(x))).*(x>0);
plot(x,y);