16进制转8进制

string的运算符操作

#include<bits/stdc++.h>/*16进制转8进制*/
using namespace std;
int n; 
int main()
{
	
	cin>>n;
	
	while(n--)
	{
		string s1="",s2="";
		cin>>s1;
		
		for(int i=0;i<s1.size();i++)
		{
			//将16进制的二进制码输入s2 
			switch(s1[i])
			{
				case '0':s2+="0000";break;
				case '1':s2+="0001";break;
				case '2':s2+="0010";break;
				case '3':s2+="0011";break;
				case '4':s2+="0100";break;
				case '5':s2+="0101";break;
				case '6':s2+="0110";break;
				case '7':s2+="0111";break;
				case '8':s2+="1000";break;
				case '9':s2+="1001";break;
				case 'A':s2+="1010";break;
				case 'B':s2+="1011";break;
				case 'C':s2+="1100";break;
				case 'D':s2+="1101";break;	
				case 'E':s2+="1110";break;
				case 'F':s2+="1111";break;
			}
		}
		/test
		
		
		/
		
		if(s2.size()%3==1)	s2="00"+s2;
		else if(s2.size()%3==2)	s2="0"+s2;
		/*
		for(int i=0;i<s2.size();i++)
		{
			cout<<s2[i];
		}
		*/
		
		int length=s2.size();
			for(int i=0;i<length;i=i+3)
			{
				int j=i;
				int put=0;
				put=(s2[j]-'0')*4+(s2[j+1]-'0')*2+(s2[j+2]-'0')*1;
				if(i==0&&put==0)	continue;
				printf("%d",put);
			}
		cout<<endl;	
	}
	return 0;
}