c++ - 符号なし/符号付きの不一致

Question

この警告メッセージの修正に問題があります。

警告C4018：'<'：符号付き/符号なしの不一致

誰かが私が問題が何であるかを見つけるのを手伝ってもらえますか？これは、次のブール関数にあります。while (i < bin.length())

#include<iostream>
#include<string>
#include<math.h>
using namespace std;

void intro();
bool isBinary(string);
void decToBin();
string getBin();
void binToDec(string);
char getChoice();
char getContinue();

int main()
{
    char choice, cont;
    string bin;

    intro();

    do{
        choice = getChoice();
            if(choice == 'b' || choice == 'B')
            {
                bin = getBin();
                bool binIsBinary = isBinary(bin);
                if(binIsBinary)
                    binToDec(bin);
            }
            else
            {
                    cout<<"Error!!! Your Number is Not Binary."<<endl;
                    cin.clear();

            }
            if(choice == 'd' || choice == 'B')
                decToBin();

        cont = getContinue();
      }
    while(cont == 'y' || cont == 'Y');
}



void intro()
{ 
    cout << "This program coverts decimal numbers to binary and vice versa."<<endl;
}

bool isBinary(string bin)
{
   int i=0;
   bool binIsBinary = true;

   while (i < bin.length())
   {
      if( bin.at(i) != '1' && bin.at(i) != '0' )
          {
          binIsBinary = false;
          }
          i++;
   }

   return binIsBinary;
}

void decToBin()
{
   int dec;
   string bin;

   cout << endl << "Please enter a decimal number:"; 
   cin  >>  dec;
   bin = "";

   while (dec != 0)
   {
      if (dec % 2 == 0)
         bin.insert(0, "0");
      else
         bin.insert(0, "1");
      dec = dec / 2;
   }
   cout << "The equivalent binary number is: " << bin << endl << endl;

}

string getBin()
{   
    string bin;

    cout << endl << "Enter a binary number: ";
    cin  >>  bin;

    return bin;
}

void binToDec(string bin)
{
    double deci;
    double len;

   len = bin.length();

   deci = 0;
   for (int i=0; i<len; i++)
       if (bin.at(i) == '1')
           deci = deci + pow(2, len-i-1);

   cout << "The equivalent decimal number is: " << deci << endl    
        << endl;
}

char getChoice()
{
    char choice;

    cout << endl << "If you would like to convert a binary to a decimal then enter b."<<endl; 
    cout << "If you would like to convert a decimal to a binary then enter d. ";
    cin >> choice;

    return choice;
}

char getContinue()
{
    char cont;

    cout << "Would you like to convert another number(Y/N)? ";

    cin >> cont;

    return cont;
}

Answer 1

さて、、、とiは、したがって、不一致です。警告を削除するには、iを作成します。intbin.length()unsignedunsigned