C语言编程 加减乘除。。。

有这样一道题，现在由于精度问题，数字加减会有误差,现要编辑一个程序，使得输入数字无误差，并给定长度在规定字符串数组(30),求加法(包含小数

我是来围观的我是来围观的我是来围观的

#include
#include
#include
using namespace std;

void main()
{
char ch[ 30 ];
memset( ch, '?', 30 );
cin>>ch;
char symbol;
callback:
cin>>symbol;
if( symbol != '+' )
{
cout << "算术仅限加法，请重新输入运算符："< goto callback;
}
char ch_1[ 30 ];
memset( ch_1, '?', 30 );
cin>>ch_1;
char c = 0;
int uIndex = 0;
int uFloatIndex = 0;
bool b1Float = false, b2Float = false;
while( c != '.' && uIndex < 30 && c != '?' )
{
c = ch[ uIndex ];
uIndex++;
}
if( c == '.' )
{
b1Float = true;
uIndex--;
uFloatIndex = uIndex;
uIndex --;
char cc = 0;
int indexc = 0;
while( indexc < 30 && cc != '?' )
{
cc = ch[ indexc ];
indexc++;
}
ch[ indexc - 2] = '?';
}
else
{
uIndex -=2;
ch[ uIndex ] = '?';
uIndex--;
c = ch[ uIndex ];
}

char c1 = 0;
int uIndex1 = 0;
int uFloatIndex1 = 0;
while( c1 != '.' && uIndex1 < 30 && c1 != '?' )
{
    c1 = ch_1[ uIndex1 ];
    uIndex1++;
}
if( c1 == '.' )
{
    b2Float = true;
    uIndex1--;
    uFloatIndex1 = uIndex1;
    uIndex1--;
    char c11 = 0;
    int index11 = 0;
    while( index11 < 30 && c11 != '?' )
    {
        c11 = ch_1[ index11 ];
        index11++;
    }
    ch_1[ index11 - 2 ] = '?';
}
else
{
    uIndex1-= 2;
    ch_1[ uIndex1 ] = '?';
    uIndex1--;
    c1 = ch_1[ uIndex1 ];
}

stringstream sstream;
int carry = 0;
int remainder = 0;
string addRet = "";
vector< int >array1, array2;
int tmpIndex = uFloatIndex + 1, tmpIndex1 = uFloatIndex1 + 1;
int normalIndex = 0;
if( b1Float && b2Float )
{
    int indexCount = 0;
    while( true )
    {
        if( ch[ tmpIndex ] != '?' )
        {
            tmpIndex++;
        }
        else
        {
            normalIndex = indexCount;
            break;
        }
        if( ch_1[ tmpIndex1 ] != '?' )
        {
            tmpIndex1++;
        }
        else
        {
            tmpIndex--;
            normalIndex = indexCount;
            break;
        }
        indexCount++;
    }
    if( ch[ tmpIndex ] != '?' )
    {
        while( ch[ tmpIndex ] != '?' )
        {
            int value = 0;
            sstream << ch[ tmpIndex ];
            sstream >> value;
            sstream.clear();
            array2.push_back( value );
            tmpIndex++;
        }
    }
    else
    {
        while( ch_1[ tmpIndex1 ] != '?' )
        {
            int value = 0;
            sstream << ch_1[ tmpIndex1 ];
            sstream >> value;
            sstream.clear();
            array2.push_back( value );
            tmpIndex1++;
        }
    }
    int tpIndex = uFloatIndex + normalIndex, tpIndex1 = uFloatIndex1 + normalIndex;
    while( true )
    {
        /*if( normalIndex == 0 )
        {
            break;
        }*/
        int value1 = 0, value2 = 0;
        if( tpIndex != uFloatIndex )
        {
            sstream << ch[ tpIndex ];
            sstream >>value1;
            sstream.clear();
            tpIndex--;
        }
        else
        {
            break;
        }

        if( tpIndex1 != uFloatIndex1 )
        {
            sstream << ch_1[ tpIndex1 ];
            sstream >> value2;
            sstream.clear();
            tpIndex1--;
        }
        else
        {
            break;
        }

        int ret = value1 + value2;
        ret += carry;
        if( ret >= 10 )
        {
            carry = ret / 10;
            remainder = ret % 10;
        }
        else
        {
            carry = 0;
            remainder = ret;
        }
        array2.push_back( remainder );
        //normalIndex--;
    }

}
else if( ( b1Float && !b2Float ) || ( !b1Float && b2Float ) )
{
    if( b1Float && !b2Float )
    {
        while( ch[ tmpIndex ] != '?' )
        {
            int value = 0;
            sstream << ch[ tmpIndex ];
            sstream >> value;
            sstream.clear();
            array2.push_back( value );
            tmpIndex++;
        }
    }
    else
    {
        while( ch_1[ tmpIndex1 ] != '?' )
        {
            int value = 0;
            sstream << ch_1[ tmpIndex1 ];
            sstream >> value;
            sstream.clear();
            array2.push_back( value );
            tmpIndex1++;
        }
    }
}

while( true )
{
    if( uIndex == -1 && uIndex1 == -1 )
    {
        break;
    }
    int value1 = 0, value2 = 0;
    if( uIndex >= 0 )
    {
        sstream << ch[ uIndex ];
        sstream >>value1;
        sstream.clear();
    }
    if( uIndex >= 0 )
    {
        uIndex--;
    }
    if( uIndex1 >= 0 )
    {
        sstream << ch_1[ uIndex1 ];
        sstream >> value2;
        sstream.clear();
    }
    if( uIndex1 >= 0 )
    {
        uIndex1--;
    }
    int ret = value1 + value2;
    ret += carry;
    if( ret >= 10 )
    {
        carry = ret / 10;
        remainder = ret % 10;
    }
    else
    {
        carry = 0;
        remainder = ret;
    }
    array1.push_back( remainder );
}

string calculateRet;
int arrayIndex = 0;
while( true )
{
    if( array1.empty() )
    {
        break;
    }
    string tmp = "";
    sstream << array1.back();
    sstream >> tmp;
    sstream.clear();
    calculateRet += tmp;
    array1.pop_back();
}
arrayIndex = 0;
if( !array2.empty() )
{
    calculateRet += ".";
    while( true )
    {
        if( array2.empty() )
        {
            break;
        }
        string tmp = "";
        sstream << array2.back();
        sstream >> tmp;
        sstream.clear();

        calculateRet += tmp;
        array2.pop_back();
    }
}
cout << "="<<endl<< calculateRet.c_str() <<endl;
system( "pause" );

}

/////////////////////////////////////////////////////////////////
//输入第一个数后按回车，然后再输入+号按回车，最后输入第二个数按回车。
//代码没有整理，勿怪，希望能帮到你。

头文件需要加sstream、vector、iostream