pascal 题目:输入一个正整数N,判断N是否为素数

用一个子程序
具体代码我给你
没测试呢
program abc;
var i,k,m,n:longint;
function isprime(n:longint):boolean;
begin
function:=true;
for i:=2 to sqrt(n) do
if n mod i=0 then
begin
function:=false;
exit;
end;
end;
begin
readln(n);
if isprime(n) then writeln('yes') else writeln('no');
end.

var k,n:longint;
begin
read(n);
case n of
2:write('Yes');
3:write('Yes');
5:write('Yes');
else begin
k:=1;
repeat
inc(k);
until(n mod k=0) or (k>sqrt(n));
if n mod k>0 then write('Yes') else write('No')
end;
end;
end.