C++ read函数读入int整形数据

#include<iostream>
using namespace std;
int read()//read函数主体部分
{
  int x=0,f=1;char ch=getchar();
  while(ch<'0'||ch>'9')
  {
    if(ch=='-')f=-1;
    ch=getchar();
  }
  while(ch>='0'&&ch<='9')
  {
    x=x*10+ch-'0';
    ch=getchar();
  }
  return x*f;
}
int main()
{
  int n=read()//这就是读入了n（注意只能用来读入int类型的数据，long long还需更改）
  system("pause");
  return 0;
}

#include <iostream> // std::cout
#include <fstream> // std::ifstream

int main () {

std::ifstream is ("test.txt", std::ifstream::binary);
if (is) {
// get length of file:
is.seekg (0, is.end);
int length = is.tellg();
is.seekg (0, is.beg);

char * buffer = new char [length];

std::cout << "Reading " << length << " characters... ";
// read data as a block:
is.read (buffer,length);

if (is)
std::cout << "all characters read successfully.";
else
std::cout << "error: only " << is.gcount() << " could be read";
is.close();

// ...buffer contains the entire file...

delete[] buffer;
}
return 0;
}