Expected unqualified-id before numeric constant

#include <iostream>
using namespace std;
float lbstokg(float);
int main()
{
  float lbs, kgs;
  cout << "\nCekini futla daxil edin: ";
  cin >> lbs;
  kgs = lbstokg(lbs);
  cout << "Cekinin kiloqramla qiymeti " << kgs <<endl;
  return 0;      
}
///
float lbstokg( float pounds )
{
  float kilograms = 0,453592 * pounds;
  return kilograms;      
}

#include <iostream>
 
using namespace std;
 
float lbstokg( float pounds )
{
  return 0.453592F * pounds;
}
 
int main()
{
  float lbs;
 
  cout << "\nCekini futla daxil edin: ";
 
  cin >> lbs;
 
  cout << "Cekinin kiloqramla qiymeti " <<  lbstokg((float)lbs) <<endl;
 
  return 0;  
    
}

return 5;

int a = 5;
return a;

return 0.453592F * pounds;

  float kilograms;
 kilograms = 0,453592 * pounds;
  return kilograms;

#include <iostream>
using namespace std;
int main()
{
  void intfrac(float, float&, float&);
  float number, intpart, fracpart;
  do {
     cout << "\nEsyavi ededi daxil edin: ";
     cin >> number;
     intfrac(number, intpart, fracpart);
     cout << "Tam hisse " << intpart << ". qaliq hisse " << fracpart << endl; 
      } while(number !=0.0);
      system("pause");
      return 0;   
}
void intfrac(float n, float& intp, float& fracp)
{
  long temp = static_cast<long>(n);
  intp = static_cast<float>(temp);
  fracp = n - intp;     
}

const char *str = "hello";
char *str1 = const_cast<char*>(str);