Interchange Roman and Integer

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


int value[] = { 1000,900,500,400,100,90,50,40,10,9,5,4,1 };
string roman[] = { "M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I" };
string solution_1(int num)
{
int i,count;
string Roman;
for (i = 0; num != 0;++i)
{
count = num / value[i];
num = num%value[i];
for (; count >0; count--)
{
Roman += roman[i];
}
}
return Roman;
}


int solution_2(string roman)
{
int i,num=0;
for (i = 0; roman[i] != '\0';)
{
switch (roman[i])
{
case 'M':
{num += 1000;
i += 1;
break;
}
case 'C':
{
if (roman[i + 1] == 'M')
{
num += 900;
i += 2;
break;
}
else
if (roman[i + 1] == 'D')
{
num += 400;
i += 2;
break;
}
else
{
num += 100;
i += 1;
break;
}
}
case 'D':
{
num += 500;
i += 1;
break;
}
case 'X':
{
if (roman[i + 1] == 'C')
{
num += 90;
i += 2;
break;
}
else
if (roman[i + 1] == 'L')
{
num += 40;
i += 2;
break;
}
else
{
num += 10;
i += 1;
break;
}
}
case 'I':
{
if (roman[i + 1] == 'X')
{
num += 9;
i += 2;
break;
}
else
if (roman[i + 1] == 'V')
{
num += 4;
i += 2;
break;
}
else
{
num += 1;
i += 1;
break;
}
}
case 'V':
{
num += 5;
i += 1;
break;
}
case 'L':
{
num += 50;
i += 1;
break;
}
}
}
return num;
}


void main()
{
int i;
string j;
cout << "Please input a Integer:";
cin >> i;
cout << i<<" to Roman is:"<< solution_1(i)<<endl;
cout << "Please input a Roman:";
cin >> j;
cout << j << " to Integer is:" << solution_2(j) << endl;
}