Plot[Piecewise[{{0,x<0},{1,x>0}}],{x,-2,2}]

unif[x_] := Piecewise[{{0,x<0},{1,0≤ x≤1},{0,x>1}}]

Plot[unif[x],{x,-2,2}]

unifc[x_]:= Integrate[unif[y],{y,-Infinity,x}]

Plot[unifc[x],{x,-2,2}]

Integrate[x*unif[x],{x,-Infinity,Infinity}]

sumden[x_]=Integrate[unif[y] unif[x-y], {y,-Infinity,Infinity}]

Plot[sumden[x],{x,-2,2}]

sum4[x_] := Integrate[sumden[y] sumden[x-y], {y,-Infinity,Infinity}]

Plot[sum4[x],{x,-3,7}]

Plot[unif[x],{x,-3,3}]

Mean[unif[x]]

Integrate[Exp[I w x] unif[x] , {x,-Infinity,Infinity}]

RandomInteger[100,10]

RandomInteger[100,10]

N[Mean[RandomInteger[100,1000]]]