c++统计文件中字符个数代码汇总

#include<iostream>
#include<fstream>
#include<cstdlib>
using namespace std;
class CntCharacters
{
private:
  int cnt;
public:
  CntCharacters():cnt(0){}
  ~CntCharacters(){}
  void opentxt(char* p)
  {
    ifstream fin;
    fin.open(p,ios_base::in);
    if(!fin.is_open())
    {
     cout<<"cannot open the file,Please make sure the file is exist!\n";
     exit(-1);
    }
    char temp;
    while(!fin.eof())
    {
     fin>>temp;
     if((temp>='a'&&temp<='z')||(temp>='A'&&temp<='Z'))cnt++;
    }
  }
  void countthecharacter()
  {
   int count=0;
   char nameoffile[80];
   cout<<"Please enter the name of file:";
   cin>>nameoffile;
  //  scanf("%s",nameoffile);
   opentxt(nameoffile);
  }
  void dis()
  {
   cout<<cnt<<endl;
  }
};
int main()
{
  CntCharacters* c=new CntCharacters;
  c->countthecharacter();
  c->dis();
  delete c;
return 0;
}

#include<iostream>
#include<fstream>
using namespace std;
int main()
{
  fstream f("test.txt",ios::in);
  char c;
  int n=0;
  while(f.get(c))n++;
  cout<<n<<endl;
  f.close(); 
  return 0; 
}

#include<iostream>
#include<fstream>
using namespace std;
int main()
{
  fstream f("test.txt",ios::in);
  char c;
  int n=0;
  while(f>>c)n++;
  cout<<n<<endl;
  f.close(); 
  return 0; 
}

//countch.cpp
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main(int argc, char* argv[])
{
  ifstream fin(argv[1]);
  if (!fin) {
    cout << "Can't open file - " << argv[1] 
      << "\nUseage : countch filename" << endl;
    return 1;
  }
  
  string d;
  int count = 0;
  while ( getline(fin, d) ) //以行为单位读入文件
    count += d.size(); //累计字符数
  
  cout << "\n Number of characters : "<< count << endl;
}