Weird characters on the output of an ifstream

#include <iostream>
#include <string>
#include <fstream>
#include <cstring>

using namespace std;

int main(){
  char a;

  cout << "give me the filename: ";
  cin >> filename;

  ifstream caroll;
  caroll.open(filename.c_str());

  while (a=caroll.get() && !caroll.eof()){
    cout << a << "  开发者_如何学编程  ";
  }

  caroll.close();
}

I am getting output full of weird chars. They are like little squares filled with 2 0's and 2 1's.

Please turn on your compilers warning level. There's a bug here:

while (a=caroll.get() && !caroll.eof()) {

This is interpreted as:

while (a = (caroll.get() && !caroll.eof()) ) {
           ^                             ^

You need to add parenthesis around the assignment:

while ((a = caroll.get()) && !caroll.eof() ) {
       ^                ^

GCC warns about this.

(Note: please post code that compiles, filename is not declared in your sample, and you're including cstring when you should be including string.)