c++ - 如何将小数转换为二进制补码字符串

Question

我真的是 C++ 的新手，我对我的程序有点困惑。该程序应该采用 2 个整数并将它们转换为具有 L 大小位的二进制补码字符串，但是当我运行该程序时，我不断收到字符串下标超出范围的错误。我可能有很多错误，如果你们能指出一些大错误就太好了。我的程序:

string reverse(string s) 
{
    string x="";
for(int i=s.length()-1;i>=0;i--)
{
    x += s[i];
}
    return x;
}
string twosComplementStringAddition(string a,string b)
{
    string c;
    int count;
    for(int i=0;i<a.length();i++)
    {
        if(count>0)
            c[i]='1';
        else if(a[i]=='1' & b[i]=='1')
        {
            c[i]='0';
            count++;
        }
        else if((a[i]=='1' & b[i]=='0')|| (a[i]=='0' & b[i]=='1'))
            c[i]='1';
        else if(a[i]=='0' & b[i]=='0')
            c[i]='0';
        count=0;
    }
    return c;
    }
    string negative(string a)
    {
        for(int i=0;i<a.length();i++)
    {
        if(a[i]=='1')
            a[i]='0';
        else
            a[i]='1';
    }
    reverse(a);
    string x="1";
    twosComplementStringAddition(a,x);
    reverse(a);
    return a;
}
string decimalToTwosComplementString(int a, int L)
{
    string s="";
    L= s.length();
    int b;
        for(int i=0;i<L-1;i++)
        {
            b=a%2;
            if(b==1)
                s[i]='1';
            else if(b==0)
                s[i]='0';
            a=a/2;
        }
        reverse(s);
        if(a<0)
        {
            negative(s);
            return s;
        }
        else
        return s;
}
int twosComplementStringToDecimal(string a)
{
    int result=0;
    if(a[0]=='0')
    {
        reverse(a);
        for(int i=0;i<a.length();i++)
    {
        if(a[i]=='1')
        {
            result= result + pow(2,static_cast<float>(i));
        }
        else if(a[i]=='0')
        {
            result = result + 0;
        }
    }
    }
    else
    {
    negative(a);
    int resulta=0;
    reverse(a);
    for(int i=0;i<a.length();i++)
{
    if(a[i]=='1')
    {
    resulta= resulta + pow(2,static_cast<float>(i));
    }
    else if(a[i]=='0')
    {
        resulta = resulta + 0;
    }
}
return resulta;
}
return result;
}
int main()
{
//Read in the bit pattern size
int L;
do
{
    cout << "Enter positive integer for the bit pattern size ";
    cin >> L;
}while (L <= 0);

//Read in two integers a and b 
int a, b;
cout << "Enter an integer a ";
cin >> a;
cout << "Enter an integer b ";
cin >> b;

//Calculate the decimal arithmetic sum of a and b and print the result
int c1 = a + b;
cout << "In decimal " << a << " + " << b << " is " << c1 << endl;

//Compute the two's complement representations of a and b
//Each integer must be represented in L-bits pattern
//Also these two's complement representations must be returned as string data types
string A = decimalToTwosComplementString(a, L);
string B = decimalToTwosComplementString(b, L);

//Print the two's complement representations of a and b
cout << "The two's complement of " << a << " is\t " << A << endl;
cout << "The two's complement of " << b << " is\t " << B << endl;

//Compute the binary sum of the two's complement representations of a and b
//The result must be returned as L-bit pattern string data type
string C = twosComplementStringAddition(A, B);

//Print the two's complement representation binary sum
cout << "The binary sum of " << A << " and " << B << " is " << C << endl;

//Convert the two's complement representation binary sum to decimal and print
int c2 = twosComplementStringToDecimal(C);
cout << "In two's complement arithmetic, " << a << " + " << b << " is " << c2 << endl;
system("Pause");
return 0;
}

对于愿意提供帮助的任何人，感谢您抽出时间!编辑:几个小时后，我终于成功了，感谢你们帮助初学者!

Answer 1

您从一个空字符串开始，并试图访问字符串中不存在的项目:

string c;
//...
for(int i=0;i<a.length();i++)
{ 
   //...
   c[i]='0'; // <-- The string is empty, but you're trying to access element i.
   //...
}

要修复错误，请将 c 字符串调整为适当的大小，以便存在这些条目。

string c;
c.resize(a.length());
//..

.