C :: Reading Files Of Unknown Size
Jan 23, 2013
I want my program to be able to read text files in the format:
number number
number number
number number...
and so on, so there are two columns of values. The problem I'm having is, there are a lot of numbers in the file, and it can vary. The program needs to read the numbers, put one column into one array, and the other in another, perform some operations on it all, and eventually pop out two different arrays. In other words, after I've got these arrays, I don't need them for much longer. I was hoping I could dynamically allocated some arrays to store the numbers and just free them as soon as I'm done with them.
If the file wasn't of such variable size or if it was guaranteed to be under a certain number of variables, I would have used:
Code:
while ( fscanf(input, "%lf %lf
", &col_1[], &col_2[]) == 2 )
{
no_rows++;
}
The problem is I want to allocate "no_rows" as the array size, which I don't have until after I have read the file.
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Mar 2, 2015
I have an assignment where I am trying to get the frac bits of a IEEE number representation. The number of exp and frac bits are given as parameters from the main, but I am unsure what bit mask to use as a one-size-fits mask.
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Apr 6, 2013
Okay, so I think I have just passed the intermediate line in my skill of c++ and my question is how do I make a program that opens unknown files extensions. for example like .plr. Because I see a bunch of files for game modifications like that, that was a good reason I started c++ too.
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Mar 1, 2015
I have a file with such a format:
string string 8 7 2
string string 7 12 19 -4
string string 1
As you can see I don't know how many numbers there are at the end. I have this code now:
while(!in.eof()) {
kr = 0;
getline(in, pavard, ','); getline(in, vard, ','); getline(in, gr, ',');
while(in.peek()) {
in >> k;
kr += k;
}
in.ignore();
}
in.close();
I tried various combinations with peek() function, but nothing worked.
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Jan 16, 2013
Consider the following piece of Code:
int ReadNumbers() {
int num;
vector<int> x;
cout << "Enter Numbers" << '
[Code] ....
The while loop is expected to terminate when the user provides an Invalid Input. But this while loop behaves unexpectedly when the user provides a 'Newline' input (by pressing Enter) and becomes an infinite loop. How can I prevent this from happening? Also I've heard that expecting invalid inputs isn't good code design. Is this true? If yes, then how can I solve my question without expecting Invalid Inputs?
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Oct 10, 2014
I want to read a string of unknown length from stdin. I tried to follow the approach from this link.
[URL]....
My code is like this:
Code:
#include <iostream>
#include <string>
using namespace std;
int n;
cin >> n;
cout << "The value of n is " << n << endl;
string str;
getline(cin, str);
cout << "The entereed string is " << str << endl;
What I have noticed is that if I take integer input from cin (cin >> n in the above code before getline, the control does not stop on getline to take str as input from the console. If I don't do (cin >> n) before getline then the control stops on getline and takes the string as input.
What is the best way to read from console multiple strings of unknown length in combination with the integers?
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May 1, 2013
So I'm making setTimeout and setInterval functions.
I have this remember function (that is part of Timing class) which takes a function pointer and a void pointer, which are remembered in that object.
Another (timing) function of that object is called in every loop of the program and when specific time passes that function calls the remembered function whit the remembered void pointer as argument.
The problem is that the functions that need to be called require unknown multiple parameters, so what I need to do is make a new class that will store the needed arguments. I make the function that needs to be called and that storage object and pass pointers to them to my remember function, when the remembered function is called it stores the data from storage object in new variables and dose it's thing.
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Apr 28, 2013
So, i got a directory full of files. Some files are duplicate and i'd like to delete those duplicate files. The only way to recognize duplicate files is their size. So how would i delete them?
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Sep 10, 2014
I have an idea which i will try to implement in C++,I want to compress file size through making my own numbering system which is 80-based number, I do really want to know whether this even possible ? I learnet that Hexadecimal uses symbols like A, B, C, D, E, F to represent 10,11,12,13,14,15 -- and that's what i want to do to my own numbering system but in a bigger scale .if possible: How can i use C++ to open a file in Hex mode ?
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Jun 10, 2013
My binary file size is 88200000 bytes, but each element should have 2 bytes. So when I use "infile.read( block , size)" , should I be using the size of the file or number of elements (44100000)?
And should block be resized to the number of bytes or the number of elements?
ifstream::pos_type size;
std::vector<int> block;
ifstream infile(filename.c_str(), ios::in|ios::binary|ios::ate);
[Code] .....
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Feb 26, 2013
How do I read a .pdf file using C++? When I try to open it using myfile.open ("example.pdf"); but all I see is some Crazy Symbols. Is there any way to open ?
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Dec 22, 2014
I cant seem to read stuff in from my students.txt file which contains this
19992195 John Smith 20 05 1995 09 09 2011 15 05 2014 55 65 72 58 80 45 40 45 66 78 88 81
20051195 Mark Dobson 20 05 1995 09 09 2011 15 05 2014 55 65 72 58 80 45 40 45 66 78 88 81
20063196 Paula O'Reilly 20 05 1995 09 09 2011 15 05 2014 55 65 72 58 80 45 40 45 66 78 88 81
20053344 Aoife Cleary 20 05 1995 09 09 2011 15 05 2014 55 65 72 58 80 45 40 45 66 78 88 81
It has something to do with the lines at the bottom of the code. It doesnt cout anything. The program just crashes upon execution. First, it asks me the amount of students i want to handle. I enter '1'. Then it asks me if i want to read in from external file and i enter 'Y'. then the exe just crashes
#include <iostream>
#include <cstddef>
#include <cstdlib>
[Code]......
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Feb 20, 2015
I have to write a program that sorts names and grades from a file and output them to another.
For example:
Name: Peter Parker
Exam 1: 95
Exam 2: 90.625
Exam 3: 91.20
Name: Mary Smith
Exam 1: 65
Exam 2: 79.1234
Exam 3: 70.24
Becomes something like this in the output file:
Name: Parker, Peter
Average Score: 92.28
Grade: A
Name: Smith, Mary
Average Score: 71.45
Grade: C
I know I'm supposed to read the whole file, but I'm getting really confused on how to take the name of each student separately without recording Exam 1, 2, and 3. I'll be able to do the average score and grade on my own.
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Jan 28, 2014
Is there a way to indicate how many records exist in a given file? For example, vectors have the vector.size() command to show the number of given elements. Is there a such command for files and records?
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Oct 3, 2014
The directions are to write a program that reads sorted integers from two separate files and merge the contents of the file to an output file (third file). The only standard output will be any errors to be reported and a “FINISHED” statement after all items have been processed.
file1.txt
2
4
6
8
10
file2.txt
1
5
11
12
15
Output.txt
1
2
4
5
6
8
10
11
12
15
This is the code I have so far, but it is not working, and I have put the two txt files in the same directory as my .cpp file. It is not working though still. What have I done wrong and how can I fix it to read these integers from the two numbers and merge the contents into a third file?
#include <iostream>
#include <fstream>
using namespace std;
int main() {
int num1;
int num2;
ifstream inputFile;
[Code] ....
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Mar 24, 2014
My question portion is attached. The code I have written is below.
#define _USE_MATH_DEFINES // for C++
#include <cmath>
#include <iostream>
#include <iomanip>
[Code].....
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Jan 16, 2015
I'm messing around with reading and writing files. The first file creates a small txt file. Simple enough
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main(){
string name;
string desc;
[Code] ....
It does what it should. It creates a text file "items.txt" .... It reads as such:
dagger,a dagger,15,10,0,1,3,1,0,0,0,1,0,0,0,0,0,1
The second file is meant to read the file and place the data back into the variables. This happens, but the data crams itself into the first variable, and the rest of them collect the trash that's in memory.
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
string name,desc;
[Code ....
I need to get "dagger" into name, "a dagger" into description, and each value with their perspective variable. I'm sure I need some type of "separator". Hopefully I can use the comma. Before it's over, I will have about a hundred items that will need to be read into a class of items.
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Jun 11, 2014
My assignment was to take numbers from two different files, and merge them into a third file in numerical order. I have everything working well, but the output shows the lowest number everytime and i'm not sure why. logical error ....
Sample:
File1 File2 File3
10 12 10
20 25 12
30 37 10
40 49 25
10
37
10
49
Here is my code as well
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
int main() {
ifstream File1, File2;
ofstream Output;
[Code] ....
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Apr 19, 2013
Code:
struct magic {
char windowsheader[2];
} magicnumbers;
struct bmp {
unsigned int sizeofthefile;
short int applicationspecific1;
[Code] .....
When I run this program, seems like it is working,at least I am sure that it gives the right file size. But if I don't use struct magic and instead use:
Code:
struct bmp {
char windowsheader[2];
unsigned int sizeofthefile;
short int applicationspecific1;
short int applicationspecific2;
//same lines with above
} bitmap_header;
And if I don't use first fread:
Code:
fread(&magicnumbers,sizeof(magicnumbers),1,fp);
Then the values which structure "bmp"'s variables get become wrong. Of course I change the related printf to:
Code:
printf("
windowsheader:%d %d
",bitmap_header.windowsheader[0],bitmap_header.windowsheader[1]);
Why does the problem happen,what is the difference between them?Why do I have to use separate structs?
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Nov 27, 2013
reading fasta formatted files. Usually ppl from computation biology know what that is but for those that are not here is a quick guide :
Fasta formatted file:
Code: >header
seqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseq
seqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseq
seqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseq
seqseqseqseqseqseqseqseqseq
>header1
seqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseqseq
seqseqseqseqseqseqseqseqseqseq
... so a very simple file format. and what i need to do is to read that into memory (vector of strings) so that header info and seq info is in two different vectors. for that i am using the following function :
Code:
sequence and headers vectors are class variables:
template <typename TStr>
template <typename FS>
void FastaSeq<TStr>::ReadFasta(FS& fs){
string line;
string seq;
while (fs >> line){
if(line.c_str()[0] == '>'){
[code].....
this code does what is suppose to do but it is EXTREMELY slow. it takes me exponentially more time to read the seq in memory then to process it. when compared to c style alternative that reads character by character it takes 13 sec with this function to do the same job that my c function does in 0.03 sec. How to improve upon this function to make it comparably fast (also i am using optimization) ?
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Sep 7, 2014
I use this header dirent.h to get list of files in directory
[URL] .....
I am using code::blocks on windows XP.
Directory "kernels_source" is placed in project's directory where I am running the code.
Code:
#include "include/types.h"
#include "include/gaussian.h"
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
[Code]....
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Dec 10, 2013
program that I am working on. I want to use fgets() in my program so I could handle multiple words from a text(to be able to handle spaces). I get a weird result when running the program.
Code: #include <stdio.h>
#include <stdlib.h>
//#include "kim.h"
#include <string.h>
[code]....
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Jul 20, 2014
I can't seem to get my program to read a file that's saved on my computer. Here's my code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
ifstream inputfile;
string name;
[Code] ....
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Dec 10, 2013
int main() {
double x, avg, max=0.0, min=100.0,totalsat=0.0, totalunsat=0.0, totalout=0.0;
int invalid=0, outstanding=0, satisfactory=0, unsatisfactory=0, kount=0;
ifstream inFile;
inFile.open("grades.txt");
[Code] ....
When the program tries to open the text file it just scrolls "0 unsatisfactory score" forever. The text file has grades in it I'm trying to sort
63
75
121
72
72
78
67
-9
80 .....
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May 19, 2014
How to write the code for this with the following requirements:
download the text file weblog.txt
This file is an Apache web log taken from the web server for St. Mary's University. When a visitor goes to their web site, the visitor's browser makes a request to the web server to view a web page, which is a file residing on the server. Each time a page is requested by a browser, the web server records information about that request. This weblog.txt holds the details of some of those requests.
Create a non-member function to read each line of the web log file. This function must do error checking to ensure that the file is opened successfully, otherwise it must provide a message like "file not available" to the user.
Each line should then be stored in a vector such that the first element of the vector is the first line of the web log file. Because each element will hold an entire line from the file, the vector should be declared as a vector of strings.
Note: You must declare the vector in a function.
Create another non-member function to sort the contents of the vector. Make sure to pass the vector by reference or your sort will disappear when the function ends! Use the sort function with #include <algorithm> to do the sort; you do not have to write your own sort algorithm.
Create one more non-member function to write the contents of the vector to a file. Each element should be on its own line in the new file. The contents of the new file should look like the original input file once your program completes, but in sorted order.
Create a main function that calls all of your non-member functions.
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Jun 5, 2014
why I'm giving "Access violation reading location 0x336827B8" and also I was able to read my data but it's giving me weird stuff. I want to write the sorted grades and the average in a new disk file. so here's my code so far here's my code
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
int avg(int sum, int size);
void swap(int *, int *);
[code]....
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