Thread: Reading Numbers from files...

ive been trying to do the same thing but that only would work for the first number in the file it wouldnt work if you hadsay 50 numbers in the file.

how would you do that?

http://www.cprogramming.com/tutorial/lesson10.html

ive read the tutorial and i still didnt se how you would choose one number outta 50 in one already created text file

Hm... how about a loop?

Quzah.

I think what your looking for is something like this:

Code:

#include <cstdlib>
#include <iostream>
#include <fstream>

using namespace std;

int main(){

    int x = 0;
    int number[10];
    ifstream myFile;

    myFile.open("File.txt"); //open file

    if(!(myFile.is_open())) { //ensure file opened
        cout <<"Error opening file";
        return 0;
    }

    while(!(myFile >> number[x] == NULL) && (x < 10)) { //check for EOF and ensure do not overrun array
        x++;
    }

    for(int i =0; i < 10; i++) {
        cout << number[i] << endl; //print result
    }
    return 0;
}

*edit*
Now if you do not know how much you are inputting you could eihter dynamically reallocate the array or just use the vector class(easiest approach).
*end edit*

Happy Coding!!

http://faq.cprogramming.com/cgi-bin/...&id=1043284351
http://faq.cprogramming.com/cgi-bin/...&id=1043284351
Andy

Oops! My bad, thanks for pointing that out. I updated my code so it doesn't show that bad, terrible bug causing thing anymore.

-Andy

Just made a few improvements on yours andy.

Code:

#include <iostream>
#include <fstream>

int main(void)
{
  
  int i = 0, j;
  int number[10];  
  std::ifstream myFile;
  myFile.open("file.txt");
  
  if(!myFile)//file doesn't exist or some other reason for it failing
  {
    
    std::cout<<"Could Not Open file.txt"<<std::endl;
    std::cin.get();
    return 0;
    
  }
  
  while(myFile>>number[i] && i < 10)//input numbers in our file only up to 10 numbers
  {
    
    i++;
    
  }
  
  for(j = 0; j < i; j++)//only printing the numbers that we read in
  {
    
    std::cout<<number[j]<<std::endl;
    
  }
  std::cin.get();    
  return 0;  
  
}

nice, I see you are a fan of the C99 standard too:

int main(void)

[edit]
How about this -

Code:

#include <iostream>
#include <fstream>
#include <stdlib.h>

int main(void){

	int x=0, arraySize=0;
	int* number = NULL;
	std::ifstream myFile;

	myFile.open("File.txt"); //open file

	if(!myFile) { //ensure file opened
		std::cout <<"Error opening file";
		std::cin.get();
		return 0;
	}

	while(!((myFile >> x)==NULL)) { //check for EOF
		if(!(number = (int*)realloc(number, (arraySize+1) * sizeof(int)))){  //resize array by one int
			std::cout << "Error allocating array" << std::endl;
			std::cin.get();
			return 1;
		}
		number[arraySize++] = x;
	}

	for(int i =0; i < arraySize; i++) {
		std::cout << number[i] << std::endl; //print result
	}
	std::cin.get();
	return 0;
}

Now of course in reality you would resize in chunks, but this is just an example.

-Andy

[/edit]

Code:

#include <iostream>
#include <fstream>
#include <vector>

int main(void)
{
  
  int x = 0, arraySize = 0, i = 0;
  std::vector<int> number;  
  std::ifstream myFile;
  myFile.open("file.txt",std::ios::in);
  
  if(!myFile)//file doesn't exist or some other reason for it failing
  {
    
    std::cout<<"Could Not Open file.txt"<<std::endl;
    std::cin.get();
    return 0;
    
  }
  
  while(myFile>>x)//input numbers in our file only up to 10 numbers
  {
    
   
    number.push_back(x);
    arraySize++;    
       
    
  }
  
  for(i = 0; i < arraySize; i++)//only printing the numbers that we read in
  {
    
    std::cout<<number[i]<<std::endl;
    
  }
  std::cin.get();    
  return 0;  
  
}

i dont think you guys understand what im saying. I am using this to save and load characters in a text (console) adventure. I create the table to a txt file and i can get it to display but i cant get the loaded characters stats to apply to the ones in the txt file.

you guys are showing me how to show all of them in the 50 numbers or characters i need to move the curser to a specific position and load from there.

If you are dealing with the file while your program is running the best thing to do is to load the file into a memory structure such as a vector and manipulate it from there. Once your program is completely done with the information save the vector back into the file. The following is an example of loading a file into a vector and then only displaying the 3rd through the 5th numbers.

Code:

#include <iostream>
#include <fstream>
#include <vector>

int loadFile(std::vector<int>*, const char*);

int main(void) {

    std::vector<int> vFile; //create vector to hold file information
    std::vector<int>::iterator iFile; // create iterator to move through vector
    int offset = 0;

    if((loadFile(&vFile, "FileDemo.txt")) == 1) { //load our file into the vector and check for an error
        std::cout << "Error Loading File" << std::endl;
        std::cin.get();
        return 1;
    }


    std::cout << "Printing from the file starting a the 3rd number and going to the 5 number" << std::endl;
    
    offset = 2;
    for(iFile = (vFile.begin() + offset); iFile < (vFile.begin() + 5); iFile++) { //move through the vector
        std::cout << *iFile << std::endl;
    }
    
    std::cin.get();
    return 0;
}
int loadFile(std::vector<int>* my_vector, const char * szfileName) {

    std::ifstream myFile;
    int myNumber = 0;

    myFile.open(szfileName, std::ios::in);//Load the file

    if(myFile == NULL) //check for error
        return 1;

    while(!((myFile >> myNumber)==NULL)) { //check for EOF
        my_vector->push_back(myNumber); // load contents of file into vector
    }

    myFile.close();
    return 0;
}

Happy Coding!!

Holy Deja-Vu, Batman!

Let's spell this out very slowly: If some one makes a post such as the origional posters, and then hasn't checked back in over 10 posts, they probably don't really want to learn anything. They want the whole thing done for them. And guess what? There are a bunch of suckers posting here who're just jumping at the chance to do it. Thank you for contributing to the never-ending flow of this type of post.

Quzah.