C++ :: Saving PNG File In Console Program / Losing Data?
Jul 18, 2013
I am working on a project that uses a web service to extract a PNG image from a web server and save it on a local machine. It's done via a system call. I can get the output of the system call to a FILE but it appears to be losing data, most notably the PNG chunk names (IHDR/PLTE/IDAT/IEND, notably). (Unfortunately piping the output to an exterior file does not work through a system call.) The end result is ~6KB smaller than the file I am intending to retrieve.
This is the code I'm using (adapted from other material I found via searches here):
ofstream png;
png.open(/*outputfile*/, ios::binary);
FILE* fp = _popen(/*SYSTEMCALL*/, "rb");
string responseString;
if(fp != NULL) {
char a[100];
while(!feof(fp)) {
fgets(a, 100, fp);
responseString += a;
}
}
_pclose(fp);
png << responseString;
Am I missing something or just doing it wrong?
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Sep 13, 2013
I have a problem when i try to save unicode to a .txt file.
I need to store in a file names that will have letters like "ăĂâÂșȘțȚîÎ"
wchar_t name []=L"ăĂâÂșȘțȚîÎ";
FILE* fang;
fang= _wfopen( L"test.txt",L"wt+,ccs=UNICODE");
fwprintf (fang, L"%ls ",name);
When i open my text file i get this: ??âÂ????îÎ
if i use
fang=fopen("test.txt","a");
I get the same result
and for
fang=fopen("ang.txt","a,css=UNICODE");
I get a runtime eroror "invalid file open mode"
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Dec 4, 2013
I have a program that saves all information temporarily into memory (into the array), however, I need a permanent save solution. I have the full program working correctly, formatted perfectly, but it's missing the file array to file output.
Essentially, whenever I'm presented with the menu I'll be able to add entries, search by last name, show the entire list, and exit and save. Whenever I select option 4 the program should save to a file "address_book.txt". Whenever I reload the program, it should load from "address_book.txt" and populate the array with the preexisting data.
My question is focused on how and where I should implement the file output. What I have thus far:
#include <iostream>
#include <string.h> //Required to use string compare
#include <fstream> //Eventually used to store array into file
using namespace std;
class AddBook{
[Code] ....
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Feb 21, 2015
My project involves writing a c program to generate a set of 70 decimal numbers. I want to save the output (these 70 numbers) as a txt file. I tried the following:
1. prt scr of output screen and pasting it in notepad. NOT WORKING
2. going to DOS SHELL and doing the following:
c:TCBIN>output.exe>>output.txt
NOT WORKING. Text file is generated, but it does not contain output. It just says:
illegal command: output.exe
What do I do?
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Mar 30, 2014
I know that returning to main() is not a good idea but how will I loop the program to go back to the position selection when the voter is done voting for the last position.
when I run the program it seems fine. getting the votes from President to PRO Position is fine. The problem is how will the next voter vote without losing the vote (tally) of the previous voter?
FLOW:
SELECT POSITION (a-e) ---> SELECT A CANDIDATE (a-c) ---> (this goes on until the position of PRO) ---> ( then go back to the POSITION SELECTION)
After every vote there is a case statement for which I can choose to vote for the next position, quit, or show results (and after showing the results it will go to the next position to vote)....
#include<iostream>
#include<string>
#include <conio.h>
using namespace std;
int pca=0,pcb=0,pcc=0,ptv=0;
[Code] .....
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Oct 24, 2013
Here's the code I'm writing:
Code:
#include <stdio.h>
#include <stdlib.h>
char* getTeamCode(char* team);
[Code]....
Why the placement of the code on line 21 above matters.
It grabs the correct string just fine. If I write a printf just below it, it prints the string it should correctly. However, if I do a printf of the string OSUteamCode below the fopen call on line 23, it prints blank.
So the first thing I did was move it below the fopen line. It worked, finding and outputting the first game in "game.csv" just fine, but not the other 11. Debugging with printf shows that the contents of OSUteamCode again disappear after the fopen call in the addLineCSV function.
I'm not understanding why that happens. The only thing I can figure is there's something going on with the file I/O commands that I just don't understand, but I can't find anything online that explains what that might be.
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Sep 28, 2014
I'm new to programming and i'm trying to do a certain task. I want to use a for loop to read certain data from a txt file and print them to a console. I'm trying to read student names and their grades.
Something like
3 // 3 represents the number of students.
George 97
Sarah 70
Maya 88
The data may vary but it's always in this format.
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Dec 4, 2014
I'm taking a programming class and currently we're doing data structures. Today, we discussed how to save square matrices column-wise with data structures. The teacher said that after the first few steps where you declare the structure, allocate the matrix, free it and get the dimension (which mostly make sense to me I think), you have to "get" and "set" the matrix by putting in something like
Code:
void setMatrixEntry(Matrix* A, int i, int j, double Aij) {
A->entries[i+j*A->m] = Aij;
}
[Code]....
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Jul 18, 2014
I am receiving packets of data from an ethernet cable. This is the line of code that is streaming in data from the ethernet cable:
size_t num_rx_samps = rx_stream->recv(&buff.front(), buff.size(), md, 3.0, enable_size_map);[code]
Here are the segments of me trying to push the packets onto a vector:
[code]
std::vector<size_t> processing_queue; //HERE IS WHERE I'M TRYING TO PUSH THE PACKETS ONTO A VECTOR
processing_queue.push_back(num_rx_samps);
[code]
I previously had my program saving to a .dat file (the commented out lines), but I need to change it to pushing values onto a vector so I can stream the data packets from the ethernet cable to be processed. However, the packets aren't being pushed onto the stack as I suspected. What do I need to change to push the data packets onto a vector? The following is the code:
[code]
#include <uhd/types/tune_request.hpp>
#include <uhd/utils/thread_priority.hpp>
#include <uhd/utils/safe_main.hpp>
#include <uhd/usrp/multi_usrp.hpp>
#include <uhd/exception.hpp>
#include <boost/program_options.hpp>
[code]....
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Mar 17, 2014
I want to connect an access database (.mdb) to my Windows Forms application - this I can do and I have no problems viewing my table in server explorer.
Some code example or template that I can use as a base to learn from - I have literally trawled Google and Youtube and cannot find what I am after.
What I want to do is have a basic form, 2 text boxes and a button to save the data to my database.
FirstName and LastName are the 2 boxes.
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Jan 6, 2015
I need to save RGB values of each pixel in a 3D array A[width][height][3]. I found a code online that transfers the bytes into an array but I cant understand how bytes are saved them so i could transfer them into an array. The truth is I dont know much about working with images at all so i have a problem working on them. How to transfer the RGB data from an .jpeg image into a 3D array? This is my code so far:
#include <iostream>
#include <jerror.h>
#include <jpeglib.h>
using namespace std;
int main(){
FILE *pic = fopen( "image.jpeg", "rb+" );
[Code] .....
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May 18, 2014
I would like to create program which will analyse bitmap so would need good concept to save data. I am interested about the theory and I realize that i must to think this carefully because bad concept could create insufficient memory or inefficient program. Basically I want my program work with HSV or HSL model so I would need to convert the bitmap to HSL, but I am not sure if I should convert it first and then analyse all pixels or should I start to analyse the bitmap and make the conversion to HSL during it. But my main question is what method to choose to save the data in memory.
Even that I would start with very small, it should work also with bigger image like image having 1200 or even 4200 px on height. So the program should first analyse all columns of pixels in the image so for example 1200x800 px image has 1200 columns. So I would like to know if is it possible to create such object which would have such structure like this
Obj->basicColumnData->black->columns[name]->group
and in the place of columns should be placed data for every column. I would look for groups of pixels in the column, so in the result the column x could bear e.g. 500 groups of information and every group should contain the range of pixels e.g. group 1 should contain y value from 0 to 20, group 2 should contain value from 25-27 and so on. So I would create 1200 columns bear many of groups. This would be contained in "black" or "white" member to contain the data. This is just simplified idea, but the whole object should contain next data not just basicColumnData... So there should be another members bearing information calculated from the selected data.
So my question is what kind of method of saving data use for this? Should I use heap and dynamic allocated memory or should I create custom class, which will define every member, but these members will have to be dynamic memory? With the dynamic memory is there problem that there could be not enough memory to create such big object?
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Jun 1, 2013
I have an application with general customer detail.
It has TextBox and radio button.
First I have used if statement then code but on first step is working fine then error is showing.
try
{
if (textBox1.Text == "")
{
[Code].....
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Feb 12, 2014
Code:
#include<stdlib.h>
FILE *Ptr_file;
Ptr_file =fopen("output.txt", "w");
struct person {
char arcFName[50],arcMName[50],arcLName[50],cGender[2];
int nDay[2],nMnth[2],nYear[4];
[Code] .....
Alright I wrote this code, i know there's some mistakes but how do you go about saving its output into a txt file?
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Jun 23, 2014
I am creating a website in which a user can upload an image to a sql database. It is converted to varbinary and then read into an Image object using a http handler to convert it to an image. this all works fine. When I open an popup window I am reading data from specific rows into textboxes, thus when the user confirms any changes the rest of the data stays the same. How can I hold the Image and redisplay it when returning to the main page after closing the pop up. It currently sets the image in the database to null as the file upload object has not been given a directory location all the time. This is my attempt at reading the image from the database and then reapplying it if the file upload is empty
private void ChangeFilm(int id)
{
SqlConnection con = new SqlConnection(my settings go here);
con.Open();
[Code].....
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Mar 16, 2015
I know how to save/open files but im just confused on where to write the code for it in this block of code :
#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
using namespace std;
const int NUM_MONTHS = 12;// Number of months
const int NUM_CATEGORIES = 6;// Number of categories
[Code] .....
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May 31, 2014
I wrote a little program. I'd like to calculation of rectangular area. How can I add data to the console?
Code:
#include <iostream>
using namespace std;
class Teglalap {
protected:
double hossz;
double szelesseg;
double terulet;
[Code] ....
But it is wrong. Nothing happen. Which line is wrong?
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May 16, 2013
I'm tinkering with a serial quick sort algorithm. Normally I use qsort() but I wanted to test this.
Somehow I loose the highest number. I can't see where I drop it.
Code:
// function to quicksort, leave them in front of qsort.
void swap(float_t *left, float_t *right){
float_t temp;
temp = *left;
*left = *right;
*right = temp;
[Code] .....
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Mar 17, 2013
Right now I'm working on an assignment where I need to take the data from on file encrypt it by adding 5 to each byte and then save it to a user specified location. I think I'm close to having it done but I've run into a hick up. After I get the user input for where the encrypted data should be saved the program seems to never end. This is the code I have so far
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
ifstream input;
ofstream output;
[Code]...
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Jan 12, 2014
I want to take the informaition from this file and save it into a struct the file conteins name age year (in char) and a grade it is somthing like this
file
Nikos Tolis 19 A 8
Iwanna Nikolaou 20 B 9
Kwstas Doukas 20 Β 6
Georgios Pappas 19 A 7
Iwannis Lekatis 20 Β 7
Nikos Ntoumas 19 A 5
Maria Oikonomou 20 B 6
Kwstas Argyrou 19 A 10
Irw Ntouma 20 B 8
Leuteris Doukas 19 A 6
I want to read till i found the '32' the space in ascii here is my code so far
Code:
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct students
{
char *name;
int age;
[Code] ....
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Jan 29, 2013
Why my code is not working?
Interface
class Person{
private:
char name[80];
short age;
public:
void get_data();
[Code] .....
This is a simple example from and old Lafore C++ book, with a few tweaks by me. The point is simple. Save object person to a *.dat file, exit the program, then start up program again, open up *.dat file, and load contents.
The first problem is the compiler is printing a bunch of Asian characters to the file (is this normal?)
The second problem is, it's not loading the object as it should, giving me a bunch of gibberish.
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Apr 21, 2014
I have been working a while with saving and retrieve structs, and I still have not got it to work. I get Segmentation fault sh "${SHFILE} . I have search this error, and it has something to do with memory, but what, since I am a beginner with saving and retrieving files. The project runs fine, and the error stated above outputs into my console window as text.
Here are my two structs:
struct checkbook {
char id[50];
double value[50];
};
struct fbook {
[Code] ....
Here is how I save and retrieve my structs:
void saveCheckbook (string file, checkbook checkbook, double initial, int counter) {
string path = "C:UsersAshwinGoogle DriveC++Checkbook" + file;
fbook save;
save.counter = counter;
save.initial = initial;
save.book = checkbook;
[Code] ...
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Jan 26, 2015
I started with C# 2 days ago, but i have made 3 "games". Its something like Cookie Clicker, very simple and very easy.
But I have problem with saving the game. I want to save values of variables to text file when i click on button, and when i click on another button i want to values of variables load. Just simple save system. How it works and so.
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Apr 24, 2015
I'm very new to c and c++ and am currently working on a Caesar cipher that grabs encrypted text from a txt file and decrypts it onto a new txt file. My code builds fine in CodeBlocks and when I run it, there is a new txt file created but it stays blank.
#include <iostream>
#include <fstream>
#include <string>
#include <stdlib.h>
#include <cstdlib>
using namespace std ;
int main(int argc, char *argv[]){
[Code] ....
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Aug 13, 2013
I'm intrested in creating programs of games and such which learns while playing and saving the information for further use. For example a tic tac toe game where the program saves evry game it won or lost and creates a tree of some kind that store the information of the game and save it in a file when the program is being quit. The problem i'm having is how to save a tree in a file efficently.
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Feb 11, 2013
Fix this code? the result is Garpish>>
<iostream>
#include<fstream>
using namespace std;
class Student {
public:
char name[10];
char address[10];
[Code] ....
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