C++ :: Ifstream Doesn't Read From The File
Aug 14, 2014
I wrote a program which was supposed to decrypt a file encrypted with the XECryption algorithm. Now, I know the decryption algorithm, but I have a problem with my ifstream object. It doesn't read anything at all, and the ofstream object just outputs a single random byte in a never ending loop. I've tried using cin, which works correctly, but it's not what I want.
Here's the code:
#include <fstream>
#include <iostream>
using namespace std;
int main() {
ifstream in("file.in", ios::in);
if (!in.is_open())
[Code]....
I'm doing this on a Windows 8(.1) pc with Code::Blocks 13.12. In the file (file.in) I have replaced the points with spaces. What is wrong with the code?
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Aug 16, 2014
i have a question, i'm studyng the string library type and i have to write this program :
Code:
std::string word;
while (std::cin >> word) {
std::cout << word << std::endl;
}
why if my input is :
hi my name is ^Z
the output is :
hi
my
name
is
why the program doesn't fall out from the while loop ?
why my program does not recognize my sequence of end of file ?
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Mar 2, 2013
I'm reading a binary file and I want to read all of the letters, but I have noticed that it doesn't read all of the letters and I think it is because of appears as data.
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Nov 13, 2013
If I have a data file.dat like this, for example:
...
other information
...
physics:
4,5,6,7
...
line:
(4,2), (2,4)
line:
(1,2), (2,3)
...
...
I want to design a class and corresponding code so that every time when it reads "line:" for the file.dat , it will push_back a new line into the line_t vector, and each time when it encounter physics it will put the values to physics, How can I implement this?
every data in file.dat is useful, they need to be read into different class type. How can I implement this?
class line_t {
public:
vector<point_t> P(2, point_t());
[Code].....
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Mar 14, 2014
I want to create a function with a return type. However, I want to use it to read from a file (ifstream) and produce multiple different types of return types. The different file types returned would be always in the same order. For example
Text File:
Name
1
12
30
Area
I want to ifstream line 1 (Name) to an array of characters.
line 2, 3, and 4 to integers.
and line 5 as a string.
The basic problem is that if I make a function with one return type, it would only return one type of data to my int main(). I suppose I could create multiple functions that would run this for different variable types and destroy the invalid types. But this seems inefficient. It is being used to load in data from a previously saved file.
So far..
//function to load a player's data
string loaded(string fileName) {
ifstream loadfile;
loadfile.open(fileName);
[Code] .....
I was thinking I could possibly do something with a counter to count the lines and assign a value based on their order. The problem is with the 1 return value of a function. Maybe there is another operation I could use?
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Feb 3, 2014
I have a text file that ifstream opens and fills some fields with the data. I've been able to get at the file, by using the precise path, but that path would be incorrect on other computers I'll be working on the project at. So, is there default location I should drop the folder in, and route to with the path? If not which Directory listing in Visual Studio 2013 should I use so the project can find the folder?
This is how I've formatted the string for ifstream.
".DataSampleActorData.txt"
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Oct 9, 2014
Is there a way to make this program work without entering the full path to a file?
Code:
ifstream ex("podatki.txt", ios_base::in); // if I type full path than program works
if(ex.is_open()) cout << "The file is open and con. with the object." << '
';
else cout << "you messed up" << '
';
int counter = 0;
[Code] ....
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Sep 9, 2013
How to open a file that the user input
ifstream InFile;
ofstream OutFile;
InFile.open("???.txt")
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May 14, 2014
Ive been having a hard time creating bin file. Whenever I append data, the data wont show in browse function. And this program works good without the bin file code.
#include <stdio.h>
#include <conio.h>
#include <stdlib.h>
[Code]....
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Jan 12, 2015
I want to access specific lines in a "*.txt" file. I've heard of seekp() and what not, but don't know how to call them as such.
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Sep 5, 2013
How do I convert ifstream to binary and display the binary at the end. I have a file that when it contains numbers it can do it but when reading strings it has trouble. It acts as if there is no binary in the file.
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Aug 3, 2012
I have a file blah.txt like this:
3 1 4
1 2 3
and here is my code to read in that file:
Code:
int x = 0, y = 0, z = 0;
ifstream data("blah.txt");
while(x != 1)
{
data >> x >> y >> z;
}
For some reason, it just keeps readin in the values: 3 1 4
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May 15, 2013
I want to read the contents of a file block (512 bytes) by block using low I/O read statements. Each record is 64 bytes long and has a pre-defined structure. The first 4 bytes are an unsigned integer; the next 20 bytes are ascii text, etc.
I have a buffer which I can access with buf[0] to buf[63] to read the first record and then buf[64] to buf[127] for the second, etc. However, I was wondering how to map a record so that I can refer to an integer as an integer and a float as float, etc. I can't create a struct and move the 64 bytes to it, as I will have alllignment/padding problems.
What is the standard way to deal with records in C?
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Mar 29, 2013
Code:
void lexer(ifstream& inputfile) {
string line;
getline(inputfile,line);
[Code] ......
I am trying to pass input file between two functions. The code compiles but immediately upon running the program, there is a "bad cast" run time error.
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Apr 28, 2014
I am currently working on a C++ program for school. I am actually not finding too much difficulty in constructing the functions, enum-types, arrays and structs, however, I am finding great difficulty in using on ifstream variable to open multiple files.
I have posted the entire code that I have so far (even though I have pinpointed the issue to not properly opening the second file in ifstream).
I spent a couple of hours getting rid of certain functions/procedures, loops and variables and I get the same output (if what I removed doesnt crash it). I also get the same output whether I "open" the second file or not (meaning I removed all of the code for it and got the same output).
Here is the code (it's not finished because I am stuck on this file issue). It's a bit messy since I am now in debug mode versus program mode:
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Feb 29, 2012
I am having an issue with passing an ifstream object to functions. Here is the code:
Code:
#include <fstream>
using namespace std;
void otherfunction (ifstream *ifs) {
...does stuff, like ifs->open(), then reads from the file...
}
int main () {
ifstream ifs();
otherfunction(&ifs);
}
Here is the error message:
Code: error: cannot convert ‘std::ifstream (*)()’ to ‘std::ifstream*’ for argument ‘1’ to ‘void otherfunction(std::ifstream*)’
Why can't I do that? What does "ifstream (*)()" even mean? And I don't want to change the structure of the program. I have reasons for declaring the ifstream object in the main function (because there are actually two functions that need access to the ifstream object -- neither of which is working).
Also, if I change the main function to be this instead:
Code:
int main () {
ifstream ifs();
ifstream *ifsptr = &ifs; //EDIT 2: forgot the ampersand
otherfunction(ifsptr);
}
I get the same error as above. However, if I change the main function to this:
Code:
int main () {
ifstream *ifsptr = new ifstream();
otherfunction(ifsptr);
}
I get all kinds of crazy errors about "undefined symbols for architecture _____". Here is the actual error message from my program (parseArgs is the real name of otherfunction)
Code:
Undefined symbols for architecture x86_64:
"std::ios_base::Init::Init()", referenced from:
__static_initialization_and_destruction_0(int, int)in cchumGBV.o
"std::ios_base::Init::~Init()", referenced from:
[Code] .....
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Apr 23, 2013
I've been working on a student data base that reads in the students name, birth date, social security, and department name (or major). I have all these items in the header files respectively; nameType, dateType, personType, and studentType.
I am now to create another header file called HWONEHEADER that contains the functions showMenu, loadStudent, insertStudent, searchByName, and SaveStudents. This is how far ive gotten
#ifndef HW
#define HW
#include <iostream>
#include <fstream>
#include <iomanip>
#include "studentType.h"
[Code] .....
Here is the cpp file i have.
int main() {
studentType department;
cin>>department;
cout<<department;
[Code] .....
I need with the HWONEHEADER using the ifstream and ofstream operators to load all the students information into a file called student.dat I'am extremely confused because i can't find anything in my textbook about using ifstream and ofstream operators.
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Mar 11, 2014
I am trying to run the code below but I receive the following error message :
Debug Assertion Failed!
Program: C:TestDebugTest.exe
File: c:program filesmicrosoft visual studio 10.0vcincludevector
Line:932
Expression:vector subscript out of range
Code:
#include <fstream>
#include <cstdlib>
#include <iostream>
#include <strstream>
#include <cstring>
#include <cmath>
#include <map>
#include "Swap.h"
#define SIZE_X 100
[Code] .....
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Jun 21, 2013
I'm doing a project that takes in a input file with Quarterback statistics. It has their name, team, completions, sacks, touchdowns, etc. It has 16 different variables in all (17 if you count first/last name as two). So I'm trying to read them and I can't figure out how to jump to the new line after it's read the file and put the information in the variables I've created.
#include <iostream>
#include <fstream>
using namespace std;
ifstream din;
void openFile() {
[Code] ....
That's the program I've written. The loop keeps displaying the first line of the file over and over. How can I get it to go to the second line, then the third, then fourth, etc? I need it to display all the lines of the file until it reaches the end of the file.
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Jun 5, 2014
I have been trying to figure this out for a text based game. Lets say your money is 500. Then you save your game, but when you start the game the starting is 50, so when you load it, you still have 500 money, I tried lots of test, and im having trouble?
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Jan 30, 2013
I'm trying to pass an reference of the object ifstream to my constructor as such:
// myClass.cpp
int main(){
ifstream file;
myClass classobj = myClass(file);}
I am defining the constructor as follows, in myClass.cpp:
myClass::myClass(ifstream &file){
// do stuff
}
I get the error of "No overloaded function of myClass::myClass matches the specified type."
Also, when I build the program, it tells me "syntax error: identifier 'ifstream'"
Also, I made sure I included this:
#include <iostream>
#include <fstream>
#include <sstream>
What am I doing wrong? How can I pass an ifstream reference to my constructor?
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Mar 15, 2013
The Objective Of This Program Is To Create A File To Write Text And Read Back The File Content. To Do That I Have Made Two Function writeFile() To Write And readFile() To Read.The readFile() function works just fine but writeFile() doesn't.
How writeFile() function Works? when writeFile() function Execute It Takes Characters User Type And When Hit Enter(ASC|| 10) It Ask "More?(Y/N)" That Means What User Want? Want To Go Next Line Or End Input?
If "Y" Than Inputs Are Taken From Next Line Else Input Ends.
But The Problem Is When Program Encounters ch==10 It Shows "More?(Y/N)" And Takes Input In cmd variable.If cmd=='Y' I Mean More From Next Line Than It Should Execute Scanf Again To Take ch I Mean User Input.But Its Not!!! Its Always Showing "More?(Y/N)" Again And Again Like A Loop.
Code:
#include <stdio.h>
void writeFile(void);
void readFile(void);
int main(){
[Code].....
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Feb 6, 2014
I am writing a simple file/text parser to read a config file for some code I am working on. It's dead simple and not particularly smart but it should get the job done. The code reads a config file:
Code:
readlength=2500000
start=0
finish=25000000
cutoff=20000
samplingfreq=250000
poles=10
filterpadding=500
}
[code]....
Here is where it gets wierd. You'll notice that there is an unused variable (filepath) in the config struct. This variable is not referenced or used anywhere in the code, ever. Yet if I comment out the declaration of char filepath[1024], the code segfaults partway through the read_config() function.
My best guess is that there is a buffer overflow elsewhere and it just so happens that the memory allocated for filepath happened to be there to catch it up until now, but I can't work out where it might be happening. With the declaration commented out, the read_config() function gets as far as reading the "padding" variable before it crashes. Yet when the declaration is there, then all the variabled are read correctly and everything seems to work.
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Mar 8, 2013
Code:
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
char buffer[256];
FILE * myfile;
myfile = fopen("read.txt","r");
[Code]...
I also got an error in printing wherein the data in read.txt is "Hello" newline "World" and my program prints world twice.
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Jun 11, 2014
I have a .txt file which I want to read from and then write a new text file, this time with sorted lines. It is easy to sort one value, but what about sorting entire lines based on one value?
I want to sort the lines based on the FIRST value.
Example text file contents:
values;data
5.01 100
2.9 342
2.69 43534
10.1 43
6.8 45324
Output: Text file containing
2.69 43534
2.9 342
5.01 100
6.8 45324
10.1 43
It's easy to do this if there was only 1 number on each line, but I do I sort all the lines based on the first number in each line?
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Mar 25, 2013
I have code that reads an input file and generates an output file .For reading the input file we have a xml file.If there is an error while reading or writing the output file the an errored file is generated. But in the errrored file the fields are not coming as in accordance with the reader xml . They are coming randomly . In the module for reading and writing the errored file list is being used . What should be done to write in the errored file as the reader xml fields.
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