【Pascal】用for/to/do编写：输入一个四位数求它各位数字的和

program hfdjh01;
var
i,a,s:integer;
begin
s:=0;{初始化}
readln(a);
for i:=0 to 4 do
begin
s:=s+(a div trunc(exp(i*ln(10)))) mod 10;{用以计算第i+1位数字}
end;
writeln(s);
end.

program gwsxjdh;
var
a,b,c,d,x:integer;
begin
readln(x);
a:=x div 1000;
b:=x div 100 mod 10;
c:=x div 10 mod 10;
d:=x mod 10;
writeln(a+b+c+d);
end.
不用使用trunc和exp函数
其实这道题就是经典的顺序结构

var i,j,p,sum:integer;
s:string;

begin
readln(s);
sum:=0;
for i:=1 to length(s) do
begin
val(s[i],j,p);
sum:=sum+j;
end;
writeln(sum);
end.