測試結果:

系統呼叫了 abort 函式！
*** Error in `/4129990/code_4129990.exe': free(): invalid pointer: 0x00007f67e97639a0 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7f67e8b737e5]
/lib/x86_64-linux-gnu/libc.so.6(+0x8037a)[0x7f67e8b7c37a]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7f67e8b8053c]
/4129990/code_4129990.exe[0x400fb6]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f67e8b1c830]
/4129990/code_4129990.exe[0x401259]
======= Memory map: ========
00400000-00402000 r-xp 00000000 fc:00 3677354                            /4129990/code_4129990.exe
00601000-00602000 r--p 00001000 fc:00 3677354                            /4129990/code_4129990.exe
00602000-00603000 rw-p 00002000 fc:00 3677354                            /4129990/code_4129990.exe
0258b000-025bd000 rw-p 00000000 00:00 0                                  [heap]
7f67e8afc000-7f67e8cbc000 r-xp 00000000 fc:00 14029440                   /lib/x86_64-linux-gnu/libc-2.23.so
7f67e8cbc000-7f67e8ebc000 ---p 001c0000 fc:00 14029440                   /lib/x86_64-linux-gnu/libc-2.23.so
7f67e8ebc000-7f67e8ec0000 r--p 001c0000 fc:00 14029440                   /lib/x86_64-linux-gnu/libc-2.23.so
7f67e8ec0000-7f67e8ec2000 rw-p 001c4000 fc:00 14029440                   /lib/x86_64-linux-gnu/libc-2.23.so
7f67e8ec2000-7f67e8ec6000 rw-p 00000000 00:00 0 
7f67e8ec6000-7f67e8edc000 r-xp 00000000 fc:00 14029454                   /lib/x86_64-linux-gnu/libgcc_s.so.1
7f67e8edc000-7f67e90db000 ---p 00016000 fc:00 14029454                   /lib/x86_64-linux-gnu/libgcc_s.so.1
7f67e90db000-7f67e90dc000 rw-p 00015000 fc:00 14029454                   /lib/x86_64-linux-gnu/libgcc_s.so.1
7f67e90dc000-7f67e91e4000 r-xp 00000000 fc:00 14029463                   /lib/x86_64-linux-gnu/libm-2.23.so
7f67e91e4000-7f67e93e3000 ---p 00108000 fc:00 14029463                   /lib/x86_64-linux-gnu/libm-2.23.so
7f67e93e3000-7f67e93e4000 r--p 00107000 fc:00 14029463                   /lib/x86_64-linux-gnu/libm-2.23.so
7f67e93e4000-7f67e93e5000 rw-p 00108000 fc:00 14029463                   /lib/x86_64-linux-gnu/libm-2.23.so
7f67e93e5000-7f67e9557000 r-xp 00000000 fc:00 14158321                   /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21
7f67e9557000-7f67e9757000 ---p 00172000 fc:00 14158321                   /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21
7f67e9757000-7f67e9761000 r--p 00172000 fc:00 14158321                   /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21
7f67e9761000-7f67e9763000 rw-p 0017c000 fc:00 14158321                   /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21
7f67e9763000-7f67e9767000 rw-p 00000000 00:00 0 
7f67e9767000-7f67e978d000 r-xp 00000000 fc:00 14029428                   /lib/x86_64-linux-gnu/ld-2.23.so
7f67e997c000-7f67e9982000 rw-p 00000000 00:00 0 
7f67e998a000-7f67e998c000 rw-p 00000000 00:00 0 
7f67e998c000-7f67e998d000 r--p 00025000 fc:00 14029428                   /lib/x86_64-linux-gnu/ld-2.23.so
7f67e998d000-7f67e998e000 rw-p 00026000 fc:00 14029428         ...訊息太長省略。

------------------------------------------------------------------------------------------------------------------------------------------------------------
程式碼:

#include <iostream>
#include <cmath>
#include <string>
using namespace std;
int roma_n(char ch) //羅馬轉數字 
{
 switch(ch)
 {
 case 'I':
 return 1;
 break;
 case 'V':
 return 5;
 break;
 case 'X':
 return 10;
 break;
 case 'L':
 return 50;
 break; 
 case 'C':
 return 100;
 break;
 case 'D':
 return 500;
 break;
 case 'M': 
 return 1000;
 break; 
 }
}
string roma_r(int a)//數字轉羅馬 
{
 switch(a)
 {
 case 1:
 return "I";
 break;
 case 2:
 return "II";
 break;
 case 3:
 return "III";
 break;
 case 4:
 return "IV";
 break;
 case 5:
 return "V";
 break;
 case 6:
 return "VI";
 break;
 case 7:
 return "VII";
 break;
 case 8:
 return "VIII";
 break;
 case 9:
 return "IX";
 break;
 case 10:
 return "X";
 break;
 case 20:
 return "XX";
 break;
 case 30:
 return "XXX";
 break;
 case 40:
 return "XL";
 break;
 case 50:
 return "L";
 break;
 case 60:
 return "LX";
 break;
 case 70:
 return "LXX";
 break;
 case 80:
 return "LXXX";
 break;
 case 90:
 return "XC";
 break;
 case 100:
 return "C";
 break;
 case 200:
 return "CC";
 break;
 case 300:
 return "CCC";
 break;
 case 400: 
 return "CD";
 break;
 case 500:
 return "D";
 break;
 case 600:
 return "DC";
 break;
 case 700:
 return "DCC";
 break;
 case 800:
 return "DCCC";
 break;
 case 900:
 return "CM";
 break;
 case 1000: 
 return "M";
 break;
 case 2000:
 return "MM";
 break;
 case 3000:
 return "MMM";
 break;
 }
}
int main()
{
 string a[2];//兩個羅馬數字 
 while(cin >> a[0])
 {
 if(a[0][0]!='#')
 {
 cin >> a[1];
 int sum[2];//兩個羅馬數字轉數字的結果 
 int n;
 int ans;//兩個羅馬數字轉數字後相減的結果(必為正)
 int t=0;//計算ans位數 
 int x;
 sum[0]=0;
 sum[1]=0;
 for(int i=0;i<2;i++)
 { 
 n=0;
 while(a[i][n]!='\0')//輸入的數字中 從左開始兩數為一組 當一組數字中的左數為空字元則停(表示到底了) 
 {
 int x,y;
 x=roma_n(a[i][n]);//左數 
 y=roma_n(a[i][n+1]);//右數 
 
 if(a[i][n+1]=='\0')//當輸入羅馬數字為奇數時 左數會有數字 右數為空字元 要把左數加入 
 {
 sum[i]+=x;
 }
 
 if(x>=y)//左數大於右數或左數等於右數 兩數相加 
 {
 sum[i]+=(x+y);
 }
 else if(x<y)//左數小於右數 大數(右數)減小數(左數) 
 {
 sum[i]+=(y-x);
 }
 n+=2;//輸入的羅馬數字中 從左開始兩數為一組 
 }
 }
 ans= sum[0]-sum[1];
 if(ans==0)
 {
 cout << "ZERO" << endl; 
 }
 else if(ans!=0)
 {
 if(ans<0)
 { 
 ans= -ans; 
 }
 x=ans;
 while(x!=0)
 {
 x/=10;
 t++; 
 }
 string str[t];
 int j=0; 
 while(ans!=0)//相減後的數字轉羅馬 
 {
 str[j]=roma_r((ans%10)*pow(10,j));
 ans/=10;
 j++;
 //cout << "j=" << j << "str=" << str[j-1] << endl;
 }
 for(int k=t-1;k>=0;k--)
 {
 cout << str[k];
 }
 cout << endl;
 }
 }
 else if(a[0][0]=='#')//輸入#終止程式 
 {
 break;
 }
 }
 return 0 ;
}