Is there a way to read and write to the same file?
I'm writing a game program and I want to save the score at the end of the game to a txt file. The txt file already contains other game scores. How do I store the score without overwriting the previous scores.
I'm just using basic fstream.
I'm writing a program using Huffman algorithm to compress text file. I have tested my program by just printing the printing ASCII character to file and it worked fine. However, now I have to implement using bits and my program doesn't work. It seems like I'm not reading or writing the right bits. Here is the result of my testing:In the input file I put abc the input file to compress it. Then I uncompress it the out out is aaa. Below is a snippet of how I read and write bits
Code:
class BitInput {
istream& in; // the istream to delegate to
char buf; // the buffer of bits
int nbits; public:
BitInputStream(istream& s) : in(s), buf(0), bufi(8) { }
[Code] ....
I have a text file containing 500 signed decimal numbers. My task is to read each entry and convert into a 16-bit 2's complement representation (binary number) and write into the another text file.
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#include <stdio.h>
struct hardware{
int recNum;
char toolName[30];
int quant;
double cost;
[Code] .....
I'm having issues with my functions working properly. I'm not sure where I'm going wrong with them and if i'm using the correct mode for the fopen.
I'm writing a program using Huffman algorithm to compress text file. I have tested my program by just printing the printing ASCII character to file and it worked fine. However, now I have to implement using bits and my program doesn't work. It seems like I'm not reading or writing the right bits. Here is the result of my testing:In the input file I put abc the input file to compress it. Then I uncompress it the out out is aaa. Below is a snippet of how I read and write bits
public:
BitInputStream(istream& s) : in(s), buf(0), bufi(8) { }
/** Read the next bit from the bit buffer.
* Return the bit read as the least significant bit of an int.
*/
int readBit(){
int i;
if(nbits == 8){
buf = in.get();
[Code] .....
I have a file of data where each line consists of 4 parameters (degree, alpha, beta and x) and a value corresponding to these, organized in increasing order of the parameters. Here's the test file I'm using:
0 1 1 0.5 3.5
1 1 1 -0.5 -0.5
1 2 0 0.2 4.5
1 3 0 0.2 -4.5
2 0 0 1.5 2.1
2 1 0 0 5.6
My code is supposed to look for a certain set of parameters (currently set to 1 2 1 1.5, which is not contained in the file) and its value. If it's there (i.e. the file contains the value for the right parameters) the program is done. If not it should calculate the value using a function JacobiPoly() and insert the wanted parameters and corresponding value in the appropriate place in the file.
I have a code in which I think everything works except the writing to file. I use an fstream so I can both read and write and open it with ios::out||ios::in. I'm also aware I need something similar to fseek in between input and output but according to [URL] .... reading and writing to the same file using the same fstream, seekp() should suffice. I'm using seekp(), but the output (in the form inout << (...)) doesn't work.
Here's the code:
fstream inout;
inout.open("inouttest.dat", ios::out | ios::in);
int degree=1, readDeg;
double alpha=2, beta=1, x=1.5, value, readAlpha, readBeta, readX, readVal;
bool foundVal=false;
streampos beforeRead=(streampos)0;
[Code] ....
I am attempting to read a ppm file. When i do it i try to write it back in another file just to see how's done and i get a terrible result. I assume the problem is something with the casting i do to the variables.
This is my image class
Image:: Image(unsigned int width, unsigned int height, bool interleaved) {
buffer = new Component [3*width*height];
this->height=height;
this->width=width;
this->buffer=Component();
[Code] .....
I am having problems either writing data to a binary file or reading from the file. Through the process of elimination I am posting the code where the data is written to file to see if I can eliminate that as an option. I know the data is being processed correctly because, through the use of another function, I can view the data.
I also know that fwrite must be including some padding because the file size ends up being 576 bytes after it is written instead of 540 bytes (the size it would be if no padding is used). Here is my struct:
Code:
typedef struct {
char teams[25];
float wins;
float losses;
float pct;
int runsScored;
int runsAgainst;
} STATISTICS;
Here is where I initialize it:
Code:
STATISTICS stats[12] = {
{"Anaheim Arrays", 0.0, 0.0, .000, 0, 0},
{"Pittsburg Pointers", 0.0, 0.0, .000, 0, 0},
{"Indianapolis Integers", 0.0, 0.0, .000, 0, 0},
[Code] ....
And here is the function that writes my data. The sA array is only used to change the scheduled games based on the variable week.
Code:
void schedule(STATISTICS stats[]) {
FILE *f;
int sA[12], week = 0, runsPerGameA = 0, runsPerGameB = 0, runsAgainstA = 0, runsAgainstB = 0;
int index, a = 0, b = 1, i = 0;
[Code] .....
Code to write data(Double type e.g 12345.67891) in text file like pattern given below. Remember to put tab between each column.
-----------------------------------------------------
Column1 Column2 Column3
Value 1 Value 2 Value 3
Value 4 Value 5 Value 6
Value 7 Value 8 Value 9
----------------------------------------------------
& Also how to read data from this file.
I'm currently working on a server for handling clients in a 2d online game and I wrote some regular fstream file code for handling the file that stores their information and I was about to implement it into the server, then I realized there might be a problem having it open multiple times concurrently, so I googled it and came up with
posts like
[URL]
I'm wondering if I can just treat it like everything else or will I have to do something specific for opening on multiple threads?
p.s. I did read those posts but I'm very new to multithreading
I'm having issues with writing to a file. more precisely, i'm trying to determine if a set of numbers are in the file. if they are already in it, don't write to the file. if not, write to the file. My problem is my program is writing all numbers, even duplicates. The sort is working.
#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
//Counter Stats
int STR;
[code].....
Both arrays arr and pointers are the same size. I am having problems reading pointers from file into a new int array.
FILE* ky_pt=fopen("stashedclient","ab");
write(fileno(ky_pt), pointers, sizeof(pointers) );
pointerindex=lseek(fileno(ky_pt), 0, SEEK_CUR );
printf("pointerindex after writing array %d
[Code] .......
I am working Visual C++ 2012. I am trying to read a GLOBE file using the following code.
#include "stdafx.h"
#include "iostream"
#include <stdio.h>
#include "stdlib.h"
#include "string.h"
#include "cmath"
#include <errno.h>
using namespace std;
/* Conversion useful */
[Code] ....
I am getting the error in the if condition (bold).
I am using visual studio 2012.....in below code i m writing data in to a test.txt file but i dont know with which key file stop accepting char...i tried ctrl+z and ctrl+d but not working ....
Code:
#include<stdio.h>
#include<conio.h>
main(){
char ch;
FILE *ptr;
[Code] ....
i've been trying to write array into file and read them into the same program again, but the output is all wrong.
Code:
#include<stdio.h>
int main()
{
FILE *fp;
char name[3][7];
int x;
}
[code]....
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.
I have to make a program that asks for your username (any)to register it. When you type it it will say something. I want to create a txt file also. so this is what I have:
#include <iostream>
#include <fstream>
using namespace std;
int main() {
int a;
{
ofstream myfile;
[Code] ....
now, how can I use the cout again to print something "Welcome to the program..."?
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.
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]....
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.
I am trying to make a project using arduino to control several power surces by time, i don't want to have an lcd, that would be easyer but i don't have enought space on my project, i want to set the time and the timing for the relays via Serial
Of curse i could set it using the serial monitor on the arduino ide, but i want to make a simple program to make the pc comunicate with the arduino and make it simpler to set the time and similar stuff. How to use one of my usb ports to print and read serial data?
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]....
I have an HTTP/1.0 webserver that I'm building in C that needs to exhibit CGI script functionality. Specifically, what I'm having trouble with is that I have two processes: process 1 is the webserver, process 2 is the CGI script. I fork in the webserver, and then call exec to run the CGI script (specifically, I used execv()). I've read from the CGI specifications in the RFC that in the case of a webserver receiving a POST request, the CGI script should read the arguments for the POST request from stdin. However, when I write to stdin, it simply echoes what was written to the terminal window and when the CGI script tries to read from stdin, it blocks.
So, with all that said, I'm pretty sure there is some simple conceptual explanation to my problem, but I can't figure it out. Do I need to use pipes or some form of interprocess communication to send the data from the webserver to the CGI script, or can it just be done with stdin (and possible stdout)?
I am using the code below to write a single instance of object "Employee" to a file in Binary mode. The write part seems to work fine, however when I try to read the single employee object from the file into memory I get a double free or corruption error.
I think this has to do with the fact that I am using a string data member in the Employee class but I don't understand what is going wrong. I have read that strings can vary in length and use dynamic memory allocation but if I write a single employee object to a file with data member 'name' equal to "John", it should be the exact same size when I read it back in right?
The code below works with no issues when I omit the string data member. Why is that? Where is the memory for the string object being "double released" when I read the employee object back into memory from the file?
I am using Linux Mint 15, Eclipse June and GCC 4.7.3 with the -std=c++11 option.
#include <iostream>
#include <fstream>
#include <string>
[Code].....
I am writing a double number in Binary format to the console of program A (in FORTRAN) with the following code:
Code:
REAL*8 A
A = 12.54
INQUIRE(6, name = xstring)
OPEN(1,file=xstring, access='stream',action='write')
WRITE (1) A
CLOSE(1)
And trying to read that number by program B (in C++) which is connected to program A by anonymous pipes. Following is the reading part of program B:
Code:
#define BUF_SIZE 5000
BOOL bSuccess = FALSE;
char Buf[BUF_SIZE];
DWORD dwRead;
for (;;) {
bSuccess = ReadFile( V_hChildStd_OUT_Rd, Buf, BUF_SIZE, &dwRead, NULL);
if( ! bSuccess || dwRead == 0 ) break;
}
Note: V_hChildStd_OUT_Rd is a handle to the output of program A.
After running the program although bSuccess becomes TRUE, Buf array does not include the number (12.54) that I am expecting. If I do the same process without using the binary format it works fine and I can read the number. I know somethings wrong with the writing or reading of binary data but I do not know what it is.
I have a 32-bit application that I've been maintaining for about 12 years and it runs on every Windows platform up to Windows 7. In all that time I've been using CWinApp::GetProfileXxxx() and CWinApp::WriteProfileXxxx() calls to read and write my program settings (about 70 settings) in the Registry. The settings are read from the Registry at start-up and written to the Registry when the program closes. There is also a method for the user to read and write the program settings to an INI file using the same code as the Registry access.
On my Windows 7 system the Registry read/write works just like it always has on all previous Windows versions. However, on some customer's Windows 7 machines there appears to be a problem with the Registry access. The program settings are either not being read from the Registry or are not being written to the Registry. I think the settings are not being written - but I don't know that. When the user uses the INI file the settings appear to be read and written.
The customer has complained a bit (I'd complain too) but doesn't have the time or doesn't want to take the time to run some simple tests for me to find out what's going on with his Windows 7 system.
So here is my question: Are there any user account settings or permissions that can block the program's access to the Registry? He claims he is an Administrator but I can't even get him to verify that.