进制转换

Posted 2020-12-11 w-w-t

题目链接

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

int Atoi( string str , int N ){      //N进制转10进制，输入string 输出int
	int ans = 0;
	for( int i = 0 ; i < str.size() ; i++){
		if(str[i] >= ‘0‘ && str[i] <= ‘9‘)
			ans = ans * N + str[i] - ‘0‘;
		else
			ans = ans * N + str[i] - ‘A‘ + 10;
	}
	return ans;
}

string Itoa( int num , int M ){   //10进制转M进制, 输入int ,输出string
	string ans = "";
	do{
		int t = num % M;
		if( t >= 0 && t <= 9 )
			ans += t + ‘0‘;
		else
			ans += t - 10 + ‘A‘;
		num /= M;	
	}while( num != 0 );
	reverse( ans.begin() , ans.end() );
	return ans;
}

int main(){
	int n , m;
	string s1;
	cin >> n >> s1 >> m;
	int num1;
	num1 = Atoi( s1 , n );   // 先把n进制转10进制
	string s2;
	s2 = Itoa( num1 , m );  //再将10进制转m进制 
	cout << s2 << endl; 
	return 0;
}