整数和浮点数加法

Posted 2021-01-03 randyniu

//本来想着将浮点数分成两部分，然后进行整数加法，唉 还是算了，太麻烦了，下面这样写就是冗余了很多。
string floatAdd(string &s1, string &s2)
{
    int idx1 = s1.find(‘.‘);
    int idx2 = s2.find(‘.‘);
    int len1 = s1.size();
    int len2 = s2.size();
    int beforePoint = max(idx1, idx2);
    int afterPoint = max(len1-1-idx1, len2-1-idx2);
    char arr[beforePoint + afterPoint + 1 + 1 + 1] = {0};
    int diff = 0;
    int i = len1 - 1;
    int j = len2 - 1;
    int idx = beforePoint + afterPoint + 1;
    int jinwei = 0;
    int add = 0;
    if(len1-1-idx1 >= len2-1-idx2)
    {
        diff = len1-idx1-len2+idx2;
        while(diff>0)
        {
            arr[idx--] = s1[i--];
            diff--;
        }
        while(j > idx2)
        {
            add = s1[i]-‘0‘ + s2[j]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --i;
            --j;
        }
    }
    else
    {
        diff = len2-idx2-len1+idx1;
        while(diff>0)
        {
            arr[idx--] = s2[j--];
            diff--;
        }
        while(i > idx1)
        {
            add = s1[i]-‘0‘ + s2[j]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --i;
            --j;
        }
    }
    arr[idx--] = ‘.‘;
    i--;
    j--;

    if(idx1 >= idx2)
    {
        while(j>=0)
        {
            add = s1[i]-‘0‘ + s2[j]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --i;
            --j;
        }
        while(i>=0)
        {
            add = s1[i]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --i;
        }
    }
    else
    {
        while(i>=0)
        {
            add = s1[i]-‘0‘ + s2[j]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --i;
            --j;
        }
        while(j>=0)
        {
            add = s2[j]-‘0‘ + jinwei;
            arr[idx--] = add%10+‘0‘;
            jinwei = add/10;
            --j;
        }
    }

    if(jinwei)
        arr[0] = ‘1‘;
    else
        arr[0] = ‘0‘;
    for(int i=0; i<=beforePoint + afterPoint + 1; ++i)
        cout << arr[i];
    cout << endl;
    string result = arr;
    result = result[0] == ‘0‘ ? result.substr(1) : result;
    return result;
}

int main()
{
    string s1 = "1111.1111";
    string s2 = "1111.1111";
    cout << floatAdd(s2, s1) << endl;
}

 

//这个是整数加法 也还是挺简单的，
string intAdd_aux(string &s1, string &s2)
{
    int i= s1.size()-1;
    int j= s2.size()-1;
    string result;
    int add = 0;
    int jinwei = 0;
    while(j>=0)
    {
        add = s1[i] - ‘0‘ + s2[j]-‘0‘ + jinwei;
        result = (char)(add%10+‘0‘)+result ;
        jinwei = add/10;
        --i;
        --j;
    }

    add = 0;
    while(i>=0)
    {
        add = s1[i] - ‘0‘ + jinwei;
        result = (char)(add%10+‘0‘)+result ;
        jinwei = add/10;
        --i;
    }
    return result;
}

string intAdd(string &s1, string &s2)
{
    int len1 = s1.size();
    int len2 = s2.size();
    string result;
    if(len1 >= len2)
    {
        result = intAdd_aux(s1, s2);
    }
    else
    {
        result = intAdd_aux(s2, s1);
    }
    return result;
}