用C ++中的文件输入

Question

I want to read from a file character by character and perform a certain operation on every character I am using the following loop:

 ifstream in
 while(in)
 {
    ch=in.get();
    //some operation
  }

I don't want to read the character in condition for while because then cursor will move to next position and I'll miss that character. The problem is that the end of the file is not properly signalled and the last character is read two times. Please give a way to avoid this Eg. if The string in the file is army it is read as armyy (when I print)

Answer 1

char ch;
while(in.get(ch)){ }  //or in>>std::noskipws>>c

Would be the proper way as the character you want is stored in ch . what is the problem with that?

If you really want it the way you want, then you may use peek() to see the next character and perform appropriate opeartion as:

char c = in.peek(); //this will give you the next character in the stream
//if its an eof, do appropriate

Answer 2

Use the other overload of get:

while (in.get(ch)) {
  // do something with ch
}

or

for (char ch; in.get(ch); ) {
  // do something with ch
}

Answer 3

You can also use sscanf for reading char.. In that example you can see that 3 input are reading from text . First two are string , last is float .. And also you can use a vector to store values.. Hope this example can be helpfull

  std::string str;
   char buf_1[50];
   char buf_2[50];
   while(std::getline(in, str))
   {
       if(sscanf(str.c_str(), "%s %s %f", buf_1, buf_2, &faceStatistics.statistics) == 3)
       {
           faceStatistics.faceName_1 = buf_1;
           faceStatistics.faceName_2 = buf_2;

           faceStat_.push_back(faceStatistics);
       }
        else
            std::cout << "No param in string  " << str << std::endl;
   }

vector assign

struct Fstat {
   std::string faceName_1;
   std::string faceName_2;
   float statistics;
};