Количество цифр в массиве строк

// ?????????? ?????????? ????????? ???? ? ??????? ?????
#include <stdafx.h/>
#include "stdring"
#include "iostream"
#include "locale"
using namespace std;
int main()
{
string str;
usingned int k=0;
int kol=0;
cout<<"??????? ??????"<< endl;
getline(cin,str);
`while(k<str.length())
{
if((str[k]>=0) &&(str[k]<=9)) kol=kol+1;
}
cout<<"?????????? ???? ? ?????? = "<< kol<<endl;
return 0;
}

// ?????????? ?????????? ????????? ???? ? ??????? ?????
 
#include "string.h"
#include "iostream"
#include "locale"
#include "cctype"
 
using namespace std;
int main()
{
    setlocale(LC_ALL, "Russian");
string str;
 int k=0;
int kol=0;
cout<<"ââåäèòå ñòðîêó"<< endl;
getline(cin,str);
while(k<str.length())
{
if((str[k]>=0) &&(str[k]<=9)) kol=kol+1;
}
cout<<"êîëëè÷åñòâî öèôð â ñòðîêå = "<< kol<<endl;
return 0;
}

#include <string>
#include <iostream>
#include <algorithm>
#include <cctype>
using namespace std;
 
bool isdigit_pred(const unsigned char val){
    return isdigit(val);
}
 
 
int main(){
    string str;
    unsigned int k=0;
    cout<<"Enter string:"<< endl;
    getline(cin,str);
    int kol=count_if(str.begin(),str.end(),isdigit_pred);
    cout<<"Count = "<<kol<<endl;
    return 0;
}

for (int i = 0; i < str.length(); ++i)
{
  if ((str[i]>='0') &&(str[i]<='9'))
  {
    ++kol;
  }
}

#include <string>
#include <iostream>
#include <locale>
#include <conio.h>
using namespace std;
int main()
{
     setlocale(LC_ALL, "Russian");
string str;
int k=0;
int kol=0;
cout<<"Ââåäèòå ñòðîêó"<< endl;
getline(cin,str);
for (int i = 0; i < str.length(); ++i)
{
  if ((str[i]>='0') &&(str[i]<='9'))
  {
    ++kol;
  }
}
cout<<"Êîëè÷åñòâî öèôð â ñòðîêå = "<< kol<<endl;
getch();
return 0;
}

#include <string>
#include <iostream>
#include <algorithm>
#include <cctype>
using namespace std;
typedef int (*ISPRED)(int);
 
int main(){
    string str;
    unsigned int k=0;
    cout<<"Enter string:"<< endl;
    getline(cin,str);
    int kol=std::count_if<string::iterator,ISPRED>(str.begin(),str.end(),isdigit);
    cout<<"Count = "<<kol<<endl;
    return 0;
}

#include <string>
#include <iostream>
#include <algorithm>
#include <cctype>
 
int main(){
    std::string str;
    unsigned int k=0;
    std::cout<<"Enter string:"<<std::endl;
    std::getline(std::cin,str);
    int kol=std::count_if(str.begin(),str.end(),isdigit);
    std::cout<<"Count = "<<kol<<std::endl;
    return 0;
}

::isdigit