example.txt

pl0编译器,c语言环境下实现,PL/0语言编译程序采用以语法分析为核心、一遍扫描的编译方法。词法分析和代码生成作为独立的子程序供语法分析程序调用。程序供语法分析程序调用。

const m = 7, n = 85;
var x, y, z, q, r;

procedure multiply;
var a, b;
	procedure plus;
	var ss;
	begin
	ss :=x
	end;

begin
	a := x; b := y; z := 0;
	while b > 0 do
	begin
		if odd b then z := z + a;
		a := 2 * a; b := b / 2;
	end
end;

procedure divide;
var w;
begin
	r := x; q := 0; w := y;
	while w > y do
	begin
		q := 2 * q; w := w / 2;
		if w <= r then
		begin
			r := r - w;
			q := q + 1;
		end;
	end
end;

procedure gcd;
var f, g;
begin
	f := x;
	g := y;
	while f <> g do
	begin
		if f < g then g := g - f;
		if g < f then f := f - g;
	end
end;

begin
	x := m; y := n; call plus;
	x := 25; y := 3; call divide;
	x := 34; y := 36; call gcd;
end.