function?dec2Bin(dec){?
??if?(!Number.isInteger(dec)||dec<0)?return?false
??if?(dec?===?0)?return?'0'
??var?binStr?=?''
??while(dec?>?1){
????binStr?=?(dec%2).toString().concat(binStr)
????dec?=?Math.floor(dec/2)
??}
??return?'1'.concat(binStr)
}

import?java.util.Stack;
public?class?Text4?{
?public?static?void?main(String[]?args)?{
??ten_two(100);
?}
?
?public?static?void?ten_two(int?num){
??
??/**
???*?x1:?存儲num整出2的結果
???*?x2:?存儲x1對2?求余的結果
???*?stack:?棧stack，存儲得到的x2的值
???*/
??int?x1?=?num;
??int?x2?=?0;
??Stack<Character>?stack?=?new?Stack<>();
??
??/**
???*?如果x1>1，則循環繼續
???*/
??while(x1>1){
???x2?=?x1%2;
???x1?/=?2;
???stack.push((char)?(x2+48));
??}
??stack.push((char)(x1?+?48));
??
??System.out.print(num?+?"從十進制變為二進制：");
??int?size?=?stack.size();
??for(?int?i?=?0;?i?<?size;?i++?){
???System.out.print(stack.pop());
??}
?}
}

講一下我的思路x是變量 ?x/2，x%2紀錄x%2用遞歸傳x/2把x%2以字符串的形式+起來