pascal中shl的用法varn:longint;a:array[1..10]of longint;procedure dfs(level,can:longint);var\x05i,p,pos:longint;begin\x05if (level>n) then \x05begin\x05\x05for i:=1 to n do write(a[i]);\x05\x05writeln;\x05\x05exit;\x05end;\x05p:=not can and (1 shl
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![pascal中shl的用法varn:longint;a:array[1..10]of longint;procedure dfs(level,can:longint);var\x05i,p,pos:longint;begin\x05if (level>n) then \x05begin\x05\x05for i:=1 to n do write(a[i]);\x05\x05writeln;\x05\x05exit;\x05end;\x05p:=not can and (1 shl](/uploads/image/z/8888132-20-2.jpg?t=pascal%E4%B8%ADshl%E7%9A%84%E7%94%A8%E6%B3%95varn%3Alongint%3Ba%3Aarray%5B1..10%5Dof+longint%3Bprocedure+dfs%28level%2Ccan%3Alongint%29%3Bvar%5Cx05i%2Cp%2Cpos%3Alongint%3Bbegin%5Cx05if+%28level%3En%29+then+%5Cx05begin%5Cx05%5Cx05for+i%3A%3D1+to+n+do+write%28a%5Bi%5D%29%3B%5Cx05%5Cx05writeln%3B%5Cx05%5Cx05exit%3B%5Cx05end%3B%5Cx05p%3A%3Dnot+can+and+%281+shl)
pascal中shl的用法varn:longint;a:array[1..10]of longint;procedure dfs(level,can:longint);var\x05i,p,pos:longint;begin\x05if (level>n) then \x05begin\x05\x05for i:=1 to n do write(a[i]);\x05\x05writeln;\x05\x05exit;\x05end;\x05p:=not can and (1 shl
pascal中shl的用法
var
n:longint;
a:array[1..10]of longint;
procedure dfs(level,can:longint);
var
\x05i,p,pos:longint;
begin
\x05if (level>n) then
\x05begin
\x05\x05for i:=1 to n do write(a[i]);
\x05\x05writeln;
\x05\x05exit;
\x05end;
\x05p:=not can and (1 shl n-1);//这个shl为啥可以做布尔类型呢
\x05while (p0) do begin
\x05\x05pos:=p and -p;
\x05\x05a[level]:=trunc(ln(pos)/ln(2))+1;
\x05\x05dec(p,pos);
\x05\x05dfs(level+1,can+pos);
\x05end;
end;
begin
\x05readln(n);
\x05dfs(1,0);
\x05readln
end.
pascal中shl的用法varn:longint;a:array[1..10]of longint;procedure dfs(level,can:longint);var\x05i,p,pos:longint;begin\x05if (level>n) then \x05begin\x05\x05for i:=1 to n do write(a[i]);\x05\x05writeln;\x05\x05exit;\x05end;\x05p:=not can and (1 shl
这是位运算!
位运算也是一种运算符,它比+-*/都快.
主要有以下几类:
a and b 把a和b都转化成二进制,分别对二进制的a和b的每一位进行and运算.
例如6 and 5 =4 ---> 6=110,5=101,6 and 5=110 and 101 =100 =4.
a or b 把a和b都转化成二进制,分别对二进制的a和b的每一位进行or运算.
例如6 or 5 =7 ---> 6=110,5=101,6 or 5=110 or 101 =111 =7.
not a 把a转换成二进制,分别对二进制的每一位进行not 运算
(根据数据类型不同结果也不同)
a shl b 等价于 ab 表示将a转换成二进制后向右移动b为.
例如:24 shr 2 =11000 shr 2 =110=6
a xor b 将a、b转成二进制后进行不进位的加法运算.
例如:6 xor 5 =3 110 xor 101 =011=3
建议初学者先不要去学习这些位运算,因为它们都是根数据类型有关,通常用于
boolean类型(只有1位),用于整数多用于优化程序方面.