PAT (Basic Level) Practice （中文）1002 写出这个数 (20分)

1.题目链接

https://pintia.cn/problem-sets/994805260223102976/problems/994805324509200384

2.题目分析

大体思路就是将各位数字相加，将和取余求出每一位的数，再将对应的中文字符串存入数组，最后输出

3.代码

#include<iostream>
#include<string>
#include<cstring>
#include<cmath>
using namespace std;
int main()
{
	string number;
	cin >> number;
	string list[101];
	int amount = 0;
	for (int i = 0; i < number.length(); i++)
	{
		amount += (number[i] - 48);
	}
	int copy = amount;
	int a = 10;
	int b = 1;
	int c = 0;
	while (amount)
	{
		int temp = amount % (int)pow(a, b);
		switch (temp)
		{
		case 0:list[c++] = "ling"; break;
		case 1:list[c++] = "yi"; break;
		case 2:list[c++] = "er"; break;
		case 3:list[c++] = "san"; break;
		case 4:list[c++] = "si"; break;
		case 5:list[c++] = "wu"; break;
		case 6:list[c++] = "liu"; break;
		case 7:list[c++] = "qi"; break;
		case 8:list[c++] = "ba"; break;
		case 9:list[c++] = "jiu"; break;
		}
		amount /= 10;
	}
	for (int i = c - 1; i >0; i--)
	{
		cout << list[i] << " ";
	}
	cout << list[0];

}

4.改进

之所以要将字符串先存入数组是因为不知道amount的位数是多少，无法从前向后求余

于是就将得出的amount先转换为字符串

5.代码

#include<iostream>
#include<sstream>
#include<cstring>
#include<string>
#include<cmath>
using namespace std;
int main()
{
	string number;
	cin >> number;
	string list[10] = {"ling","yi","er","san","si","wu","liu","qi","ba","jiu"};
	int amount = 0;
	for (int i = 0; i < number.length(); i++)
	{
		amount += (number[i] - 48);
	}
	string transamount;
	stringstream ss;
	ss << amount;
	ss >> transamount;
	int i = 0;
	for (; i < transamount.length()-1; i++)
	{
		cout << list[transamount[i] - '0']<<' ';
	}
	cout << list[transamount[i] - '0'];

}

6.附上string与int相互转换的方法

使用stringstream

（参考https://www.cnblogs.com/houchen/p/8984164.html）

1.数字转换为字符串

#include <string>

  #include <sstream>

  int main(){
    double a = 123.32;
    string res;
    stringstream ss;          定义流ss
    ss << a;                       将数字a转化成流ss
    ss >> res;                    将流ss转化成字符串
    return 0;
  }

2.字符串转换为数字

#include <string>

  #include <sstream>

  int main(){
    double a ;
    string res= "123.32";
    stringstream ss;  
    ss << res;                  
    ss >> a;
    return 0;
  }

int 转string使用to_string函数

#include<iostream>
#include<string>
using namespace std;
int main()
{
	int n = 100;
	string ss = to_string(n);
	cout << ss;
}

如果是小数转换为字符串的话使用该方法会自动添加许多0

sprintf函数、sscanf函数

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

int main()
{
	char str[10];
	int a = 1234321;
	//将整数转化为字符串
	sprintf(str, "%d", a);
	cout << str;
    char str1[10];


	double b = 123.321;
	//将浮点数转化为字符串
		sprintf(str1, "%.3lf", b);
	cout << str1;
}

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

int main()
{
    char str[]="1234321";
    int a;
    sscanf(str,"%d",&a);//注意这里的&
    cout<<a<<endl;

    char str1[]="123.321";
    double b;
    sscanf(str1,"%lf",&b);
    cout<<b<<endl;
    return 0;
}