PAT1005. Spell It Right (20)

题目 PAT1005. Spell It Right (20)

Given a non-negative integer N, your task is to compute the sum of all the 
digits of N, and output every digit of the sum in English.

Input Specification:

Each input file contains one test case. Each case occupies one line which 
contains an N (<= 10100).

Output Specification:

For each test case, output in one line the digits of the sum in English words. 
There must be one space between two consecutive words, but no extra space at 
the end of a line.

Sample Input:
12345
Sample Output:
one five

题意理解

给出数组的和逐位用英文拼写。

题目分析

第一次使用了递归来拼写，但有更简单的方法，通过string定义一个字符串，按顺序拼写即可。

代码

递归

#include <iostream>
#include <cstdio>
#include <cstdlib> 
#include <algorithm>
#include <queue>
#include <stack>
#include <cstring>
#include <map>
using namespace std;
const int N = 110;

void english(int n){
    switch(n){
        case 0:cout << "zero";break;
        case 1:cout << "one";break;
        case 2:cout << "two";break;
        case 3:cout << "three";break;
        case 4:cout << "four";break;
        case 5:cout << "five";break;
        case 6:cout << "six";break;
        case 7:cout << "seven";break;
        case 8:cout << "eight";break;
        case 9:cout << "nine";break;
    }   
}

void spell(int n){
    if(n / 10 == 0){
        english(n);
    }else{
        spell(n / 10);
        cout << " ";
        english(n%10);
    }
}
int main(int argc, char *argv[]) {
    char c[N];
    int sum = 0,i = 0;
    //freopen("Input.txt","r",stdin);
    cin >> c;
    while(c[i] != '\0'){
        sum += (c[i] - '0');
        i++;
    }
    //cout << sum << endl;
    spell(sum);
    return 0;
}

非递归

#include <iostream>
#include <cstdio>
#include <cstdlib> 
#include <algorithm>
#include <queue>
#include <stack>
#include <cstring>
#include <map>

using namespace std;

int main(int argc, char *argv[]) {
    string s;
    int sum = 0;
    //freopen("Input.txt","r",stdin);
    cin >> s;
    for(int i = 0;i < s.length();i++){
        sum += (s[i] - '0');
    }
    string t = to_string(sum);
    string arr[10] = {"zero","one","two","three","four","five","six","seven","eight","nine"};
    cout << arr[t[0] - '0'];
    for(int i = 1;i < t.length();i++){
        cout << ' ' << arr[t[i] - '0'];
    }
    return 0;
}

问题

为什么我使用to_string会报错，IDE：Dev-C++，编译器：minGW GCC 4.7.2 32-bit

[Error] 'to_string' was not declared in this scope 

参考

https://www.liuchuo.net/archives/1885