File I/O?

ok, here's my problem. i can write to a file just great. it formats it exactaly how i want it to. the problem is that i can't read from a file. everytime i try to read from a file and i want something other than a char array, it doesn't read correctly, and with my current reading system it won't read correctly for even that. can i get a few pointers?

i'm confident that this is where my problem is.

Code:

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        char  inName[100];                // name of the food
        int          inCategory;                // what kind of food
        float inCalories;                // calories
        float inCarbohydrates;        // grams
        float inFat;                        // grams
        float inCholesterol;        // grams
        float inSodium;                        // grams
        float inProtein;                // grams
        ifstream in("data.txt");
        counter = 0;
        while(in.peek() != EOF)
        {
                in.getline(inName, 100, '~');
                inCategory = (int)in.get();
                inCalories = (float)in.get();
                inCarbohydrates = (float)in.get();
                inFat = (float)in.get();
                inCholesterol = (float)in.get();
                inSodium = (float)in.get();
                inProtein = (float)in.get();

                data[counter].setname(inName);
                data[counter].setcategory(Category(inCategory));
                data[counter].setcalories(inCalories);
                data[counter].setcarbohydrates(inCarbohydrates);
                data[counter].setfat(inFat);
                data[counter].setcholesterol(inCholesterol);
                data[counter].setsodium(inSodium);
                data[counter].setprotein(inProtein);

                counter++;
        }
        in.close();

---

but i don't know what i need to change.

this is what is in data.txt

Quote:

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Multi grain bread~6 90 16 0 .5 .125 4

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the goal is to get it to read until the tild, and made that the name, then read the next number, make that the food group, red next number, make that the calories, etc etc.

thanks for taking the time to view my thread :)

My choice would be getline to read the whole line, then sscanf to parse the line.

get with no parameters takes a byte outta the file and stores it in your variables, which is not what you want. Your input method in general needs to be more refined. Given the way you like to do things, for you I suggest a combination of getline and stringstream, or strtol().

How about using the >> opertor? You could even go as far as to creat your own extractors if you have any odd data types (not that you do - they are all floats and a string).

If that is too complicated then read the whole lof (line by line) into a string and use the string manipulation functions to sort it all out. I mean the C++ std::string, rather than char{100]. They are very powerful and really easy to use. You can, for example, set the delimiter (tilde for your first string) vey simply:

Code:

---

while(in)
{        in.getline(cbuf,MAX_BUF_SIZE); //Whole line
        string sbuf(cbuf);
        if(sbuf.empty())
                continue; //Blank line, nothing to do...
        //Get inCaegory (~ terminated)
        int ind=sbuf.find_first_of("~");
        inCategory=sbuf.substr(0,ind);
        ...
}

---

Hope that helps.

wow, awesome, thats a lot of help :) you guys rock. i'm not allowed to use any strings in this program, so i have to use char arrays though :-/

i couldn't figure stringstream or strtol, so i decided to go with sscanf, which is working great. for the first time its actualy reading from a file corectly.

it's 100% working now.

this is what it looks like now.

Code:

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                char  inAll[100];                // the data as retrieved from file.
                char  inName[100];                // name of the food
                int          inCategory;                // what kind of food
                float inCalories;                // calories
                float inCarbohydrates;        // grams
                float inFat;                        // grams
                float inCholesterol;        // grams
                float inSodium;                        // grams
                float inProtein;                // grams
                ifstream in("data.txt");
                counter = 0;
                while(in.peek() != EOF)
                {
                        in.getline(inName, 100, '~');
                        in.getline(inAll, 100, '\n');
                        sscanf( inAll, "%d %f %f %f %f %f %f", &inCategory, &inCalories, &inCarbohydrates, &inFat, &inCholesterol, &inSodium, &inProtein);

                        data[counter].setname(inName);
                        data[counter].setcategory(Category(inCategory));
                        data[counter].setcalories(inCalories);
                        data[counter].setcarbohydrates(inCarbohydrates);
                        data[counter].setfat(inFat);
                        data[counter].setcholesterol(inCholesterol);
                        data[counter].setsodium(inSodium);
                        data[counter].setprotein(inProtein);
                        // i figure that 30 will be enough.
                       
                        counter++;
                }
                counter--;
                counter--;
                in.close();
        }

---

dunno why i had to have 2 "counter--"'s, but everything works great now :) thanks again guys!

My sscanf version went something like this.

Code:

---

#include <iostream>
#include <fstream>
#include <cstdio>
using namespace std;

int main()
{
  char  line[100];        // name of the food
  char  name[100];        // name of the food
  int  inCategory;      // what kind of food
  float inCalories;      // calories
  float inCarbohydrates;  // grams
  float inFat;            // grams
  float inCholesterol;    // grams
  float inSodium;        // grams
  float inProtein;        // grams
  ifstream in("file.txt");
  while ( in.getline(line, sizeof line) )
  {
      if ( sscanf(line, "%99[^~]~%d %f %f %f %f %f %f", name,
                  &inCategory, &inCalories, &inCarbohydrates, &inFat,
                  &inCholesterol, &inSodium, &inProtein) == 8 )
      {
        // ...
//      ++counter;
      }
  }
  return 0;
}

---

If you only increment your loop counter on success, then you don't need to do any decrements.

The stringstream version is fairly similar, and I chose to ditch char arrays for strings as well, much like citizen suggested.

Code:

---

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>
using namespace std;

int main()
{
  string line;
  string name;            // name of the food
  int    inCategory;      // what kind of food
  float  inCalories;      // calories
  float  inCarbohydrates;  // grams
  float  inFat;            // grams
  float  inCholesterol;    // grams
  float  inSodium;        // grams
  float  inProtein;        // grams
  ifstream file("file.txt");
  while ( getline(file, line) )
  {
      istringstream iss(line);
      if ( getline(iss, name, '~') &&
          iss >> inCategory >> inCalories >> inCarbohydrates >> inFat
              >> inCholesterol >> inSodium >> inProtein )
      {
        // ...
      }
  }
  return 0;
}

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