i have a problem with one assignment that i have. I have to read a .ts file, read the packets that are inside and extract header information from each packet.
I have created a struct Packet that will hold all the info of the header, and i also have a vector in which i will push_back each Packet.
The problem is that the for loop stops for some reason on the 163rd loop. If i loop until lets say i=160, then the code escapes ends the loop, but when i print the vector.size() i get a really huge number which doesn't make sense. i guess it should be an integer value as high as the pushed back number of Packets.Here is the code that i have so far:
int main() {
FILE *ts_file = NULL;
ts_file = fopen64("/home/ddd/Desktop/Assignment/Streams/ddd.ts", "rb");
if (ts_file == NULL){
cout << "No file detected on this path, try again" << endl; // prints !!!Hello World!!!
}
TS_Analyzer *ts_analyzer;
ts_analyzer->parse_file(ts_file);
cout << "Finished main" << endl;
return 0;
}
void TS_Analyzer::parse_file(FILE *ts_file){
cout << "Inside parser" << endl;
fseek(ts_file,0,SEEK_END);
long file_size = ftell(ts_file);
rewind (ts_file);
number_of_packets = file_size/PACKET_SIZE;
unsigned int current_header_add = 0;
unsigned int i=0;
for (unsigned int j=1; i<number_of_packets; j++)
{
i++;
unsigned char TS_raw_header[4];
cout << "current position " << int(current_header_add) << endl;
current_header_add = ftell(ts_file);
fread(&TS_raw_header, sizeof(TS_raw_header), 1, ts_file);
Packet current_packet;
current_packet.sync_byte = TS_raw_header[0];
current_packet.transport_error_indicator = (TS_raw_header[1] & 0x80) >> 7;
current_packet.payload_start_indicator = (TS_raw_header[1] & 0x40) >> 6;
current_packet.transport_priority = (TS_raw_header[1] & 0x20) >> 5;
current_packet.PID = ((TS_raw_header[1] & 31) << 8) | TS_raw_header[2];
current_packet.transport_scrambling_control = (TS_raw_header[3] & 0xC0);
current_packet.adaption_field_control = (TS_raw_header[3] & 0x30) >> 4;
current_packet.continuity_counter = (TS_raw_header[3] & 0xF);
stream_packets.push_back(current_packet);
//cout << hex << int(current_packet.PID) << endl;
//cout << dec << "continuity counter " << int(current_packet.continuity_counter) << endl;
cout << " i " << int(i) << endl;
fseek(ts_file, 184, SEEK_CUR);
}
cout << "##" << endl;
cout << stream_packets.size() << endl;
}
class TS_Analyzer: public Analyzer {
public:
TS_Analyzer();
~TS_Analyzer();
struct Packet {
unsigned char sync_byte;
unsigned char transport_error_indicator;
unsigned char payload_start_indicator;
unsigned char transport_priority;
unsigned int PID;
unsigned char transport_scrambling_control;
unsigned char adaption_field_control;
unsigned char continuity_counter;
};
std::vector<Packet>stream_packets;
int number_of_packets = 0;
void parse_file(FILE *);
};
Any ideas of why the vector push_back breaks the for loop and why i cannot get a correct vector size?
If I put this code through the clang compiler, I get an error on following code:
TS_Analyzer *ts_analyzer;
ts_analyzer->parse_file(ts_file);
>> variable 'ts_analyzer' is uninitialized when used here
I guess you are encountering undefined behavior: As ts_analyzer as ptr is any random value, the data in its members is also very random.
I'm actually surprised that this code runs at all without crashing, though you can always be lucky.
If you like to fix this, try avoiding pointers by creating the object at the stack:
TS_Analyzer ts_analyzer;
ts_analyzer.parse_file(ts_file);
or if you really need allocated memory, at least fill in the pointer:
auto ts_analyzer = std::make_unique<TS_Analyzer>();
ts_analyzer->parse_file(ts_file);
Related
I have such piece of code:
typedef struct reader
{
char name[50];
char card_num[50];
char title[100];
}reader_t;
int main()
{
vector<reader> vec;
ifstream input_file("D:\\lab.txt", ios::binary);
reader_t master[1];
input_file.read((char*)&master, sizeof(master));
for (size_t idx = 0; idx < 1; idx++)
{
reader temp;
strcpy(temp.name, master[idx].name);
strcpy(temp.card_num, master[idx].card_num);
strcpy(temp.title, master[idx].title);
vec.push_back(temp);
cout << "Name: " << master[idx].name << endl;
cout << "Card num: " << master[idx].card_num << endl;
cout << "Title: " << master[idx].title<<endl;
}
cout << vec.size();
getchar();
}
What is does: it reads structures from binary file into an array of structures,copies them into vector and displays structure.And yes, I do need to do like this - I need to store structures from file in vector and this is the only working way to do it I could find(if you can tell, how to read structures to vector directly from file - you are welcome).
So,everything works fine, but the problem is that I need to create a function which would be able to do the same, but with dynamic array.I wrote something like this:
void read_structs(int vec_size)
{
ifstream input_file("D:\\lab.txt", ios::binary);
//Here I commented 2 ways how I tried to create a dynamic array of structs
//reader* master = new reader[vec_size];
//reader* master = (reader*)malloc(sizeof(reader) * vec_size);
input_file.read((char*)&master, sizeof(master));
for (size_t idx = 0; idx < vec_size; idx++)
{
reader temp;
strcpy(temp.name, master[idx].name);
strcpy(temp.card_num, master[idx].card_num);
strcpy(temp.title, master[idx].title);
vec.push_back(temp);
cout << "Name: " << master[idx].name << endl;
cout << "Card num: " << master[idx].card_num << endl;
cout << "Title: " << master[idx].title<<endl;
}
}
And that worked fine too unless I tried to run it.VS wasn't higlighting error in my code, it just was throwing an exception right as the moment when the program tried to access master[0].name.
There is absolutely no point in the temp struct. See, the
vec.push_back(temp);
is already using copy constructor, so copy constructor must work and then the set of strcpy is not doing anything different from that, so just go with
vec.push_back(master[0]).
You can't read into vector directly. You do need to read into temporary. So that is correct. Except I suppose you want to read all entries from the file no matter how many of them there are, so you need to put the read itself also into the loop.
There is not much point in creating an array of one element.
reader_t master[1];
input_file.read((char*)master, sizeof(master));
// ^ you *don't* need & here, arrays degrade to pointers automatically
and
reader_t master;
input_file.read((char *)&master, sizeof(master));
// ^ but you do need & here.
are equivalent. I would go with the later.
So we are basically down to:
reader temp; // calling it temp; the master name makes no sense.
while (input_file.read((char*)&temp, sizeof(temp)))
// read returns input_file and input_file is false if last operation failed
{
vec.push_back(temp);
// verify the stored values by reading back vfrom vec.back().
cout << "Name: " << vec.back().name << endl;
cout << "Card num: " << vec.back().card_num << endl;
cout << "Title: " << vec.back().title<<endl;
}
In the second example, you didn't initialize master, so it obviously crashed.
There is a more C++ approach though. First, you define a read operator for the structure:
std::istream &operator>>(std::istream &in, reader &r) {
return in.read((char *)&r, sizeof(r));
}
and then you simply read the vector using the istream_iterator:
vec.assign(std::istream_iterator<reader>(input_file),
std::istream_iterator<reader>());
and the standard library will generate the above loop for you.
I'm working on a project that involves binary files.
So I started researching about binary files but I'm still confused about how to write and fill a vector from that binary file that I wrote before
Here's code: for writing.
void binario(){
ofstream fout("./Binario/Data.AFe", ios::out | ios::binary);
vector<int> enteros;
enteros.push_back(1);
enteros.push_back(2);
enteros.push_back(3);
enteros.push_back(4);
enteros.push_back(5);
//fout.open()
//if (fout.is_open()) {
std::cout << "Entre al if" << '\n';
//while (!fout.eof()) {
std::cout << "Entre al while" << '\n';
std::cout << "Enteros size: "<< enteros.size() << '\n';
int size1 = enteros.size();
for (int i = 0; i < enteros.size(); i++) {
std::cout << "for " << i << '\n';
fout.write((char*)&size1, 4);
fout.write((char*)&enteros[i], size1 * sizeof(enteros));
//cout<< fout.get(entero[i])<<endl;
}
//fout.close();
//}
fout.close();
cout<<"copiado con exito"<<endl;
//}
}
Here's code for reading:
oid leerBinario(){
vector<int> list2;
ifstream is("./Binario/Data.AFe", ios::binary);
int size2;
is.read((char*)&size2, 4);
list2.resize(size2);
is.read((char*)&list2[0], size2 * sizeof(list2));
std::cout << "Size del vector: " << list2.size() <<endl;
for (int i = 0; i < list2.size(); i++) {
std::cout << i << ". " << list2[i] << '\n';
}
std::cout << "Antes de cerrar" << '\n';
is.close();
}
I don't know if I'm writing correctly to the file, this is just a test so I don't mess up my main file, instead of writing numbers I need to save Objects that are stored in a vector and load them everytime the user runs the program.
Nope, you're a bit confused. You're writing the size in every iteration, and then you're doing something completely undefined when you try to write the value. You can actually do this without the loop, when you are using a vector.
fout.write(&size1, sizeof(size1));
fout.write(enteros.data(), size1 * sizeof(int));
And reading in:
is.read(&list2[0], size2 * sizeof(int));
To be more portable you might want to use data types that won't change (for example when you switch from 32-bit compilation to 64-bit). In that case, use stuff from <cctype> -- e.g. int32_t for both the size and value data.
I'm having a little trouble with my code. It's pretty much supposed to open two files, and compare the first twenty line of the file "StudentAnswers.txt" [inputted as a char into a char array] against a char value in (each line of another file) "CorrectAnswers.txt" in another array at the same position (index). It's like a linear search, but the same position in the arrays. Then a report should be displayed, detailing which question the student missed, the given answer, the correct answer, and if the student passed (got >= 70%) or not, like the following:
Report for Student X:
2 (A/D), 3 (C/D), 5(D/A)
This student passed the exam!
Then it should clear the SAArray, and feed the next twenty lines from StudentAnswers.txt, and start the process all over again. I guess the program has to determine the number of students from (lines of 'StudentAnswers.txt' file / 20).
I'm having trouble displaying the report, and having the array clear itself after the program. I'm guessing this can be done with a while loop and an accumulator for the number of students (to be determined by above equation).
Also, Visual Studio seems to go to "Missed __ questions for a total of ___ %", and then keep looping -858993460.
Any help would be appreciated.
#include <iostream>
#include <fstream>
#include <string>
#include <array>
#include <algorithm>
using namespace std;
void GradeReturn(char[], char[], int, int, int);
string PassFail(float);
int main()
{
ifstream SA("StudentAnswers.txt");
ifstream CA("CorrectAnswers.txt");char CAArray[20];
char SAArray[20];
// char SA2Array[20];
bool isCorrect;
int correct;
int incorrect;
int counter;
correct = 0;incorrect = 0;
counter = 0;
cout << endl;
if (!SA.fail())
{
cout << "'StudentAnswers.txt' file opened successfully." << endl;
cout << "'CorrectAnswers.txt' file opened successfully." << endl << endl;
int a = 0;
int b = 0;
while (a < 20)
{
CA >> CAArray[a];
a++;
} // while loop to feed char into the array
while (b < 20)
{
SA >> SAArray[b];
b++;
}
} // while loop to feed char into array
CA.close(); // closing "CorrectAnswers.txt"
SA.close(); // closing "StudentAnswers.txt"
GradeReturn(&CAArray[counter], &SAArray[counter], correct, incorrect, counter);
return 0;
}
void GradeReturn(char CAArray[], char SAArray[], int correct, int incorrect, int counter)
{
float percent;
float hundred;
int student;
int catcher[20];
int writeCatcher; int starter;
int catcher_size;
student = 0;
writeCatcher = 0;
catcher_size = ((sizeof catcher) / 4);
while (counter < 20)
{
if ((CAArray[counter]) == (SAArray[counter]))
{
correct++;
cout << "Good job!" << endl;
} // correct handling
else
{
incorrect++;
cout << "You got question " << counter << " wrong." << endl;
counter >> catcher[writeCatcher];
writeCatcher++;
} // incorrect handling
counter++;
} // while loop to determine if a student got a question right or wrong
static_cast <float> (incorrect); // float conversion
cout << endl; // for cleanliness
percent = ((static_cast <float> (correct)) / 20); // percentage
hundred = percent * 100;
PassFail(percent);
if (PassFail(percent) == "pass")
{
student++;
cout << "Report for Student " << student << ":" << endl;
cout << "-----------------------------" << endl;
cout << "Missed " << incorrect << " questions out of 20 for ";
cout << hundred << " % correct." << endl << endl;
starter = 0;
while (starter < (sizeof catcher)
{
if(1=1)
{
catcher_size
}
else
{
cout << "";
starter++;
}
}
}
else if (PassFail(percent) == "fail")
{
student++;
cout << "Missed " << incorrect << " questions out of 20 for ";
cout << hundred << " % correct." << endl << endl;
while (starter < catcher_size)
{
if ((catcher[starter]) == -858993460)
{
starter++;
}
else
{
cout << "";
starter++;
}
}
}
return;
}
string PassFail(float percent)
{
if (percent >= 0.70) // if <pass>
{
return "pass";
}
else // if <fail>
{
return "fail";
}
cout << endl;
}
To get a loop you should keep streams open instead of closing them after reading 20 lines.
As pseudo code that would be:
a = 0;
while(streams_not_empty)
{
CA >> CAArray[a];
SA >> SAArray[a];
++a;
if (a == 20)
{
GradeReturn(&CAArray[counter], &SAArray[counter], correct, incorrect, counter);
a = 0; // Reset a
}
}
CA.close(); // closing "CorrectAnswers.txt"
SA.close(); // closing "StudentAnswers.txt"
You would also need to pass correct, incorrect, counter by reference so that the GradeReturn can change their value and their by do the accumulation.
Like:
void GradeReturn(char CAArray[], char SAArray[], int& correct, int& incorrect, int& counter)
Further you shouldn't rely on being able to read exactly Nx20 lines from the files every time. A file could have, e.g. 108 (5x20 + 8) lines, so you code should be able to handle the with only 8 lines. In other words, don't hard code 20 in your function like while (counter < 20). Instead pass the number of lines to be handled and do while (counter < number_to_handle).
Something like this as pseudo code:
a = 0;
while(streams_not_empty)
{
CA >> CAArray[a];
SA >> SAArray[a];
++a;
if (a == 20)
{
GradeReturn(&CAArray[counter], &SAArray[counter], correct, incorrect, counter, a);
// ^
a = 0; // Reset a
}
}
if (a != 0)
{
// Process the rest
GradeReturn(&CAArray[counter], &SAArray[counter], correct, incorrect, counter, a);
}
CA.close(); // closing "CorrectAnswers.txt"
SA.close(); // closing "StudentAnswers.txt"
One problem you have is you're trying to compare C-style strings with the == operator. This will compare them essentially as if they were pointers to char, i.e. compare whether they point at the same location in memory, not compare the contents of the string. I urge you to look up array-decay and c-string variables to understand more.
Specifically, if (PassFail(percent) == "pass") isn't going to do what you want it to. strcomp doc, strncmp doc using std::string variables instead of c-style strings would all work, but it would be better simply to compare percent to a value, i.e. if(percent >= 0.70 directly instead of calling PassFail and comparing a string.
There are many other issues here also, you at one point call PassFail but do nothing with the return value. The only side affect of PassFail is cout << endl, if that's what you intend, it's a poor decision and hard to read way to put a newline on the console.
Try asking your compiler for more warnings, that's often helpful in finding these types of issues. -Wall -Wextra work for gcc, you may have to read your compiler manual...
Im allocating 25,000,000,000 units of these :
struct test
{
public:
test();
void insert(unsigned int var1, unsigned int var2, unsigned long var3);
bool isEmpty() const;
unsigned char * data;
};
test::test()
{
data = NULL;
}
bool test::isEmpty() const
{
return (data == NULL);
}
unsigned long index = 25000000000;
like this :
test *something = new (nothrow) test[index];
if (!something)
{
cout << "Error allocating memory for [something]" << endl;
return ;
}
cout << "DONE !" << endl;
then i even made sure its data initialized to NULL.
unsigned long j=0;
while (j<index)
{
something[j].data = NULL;
j++;
}
And its all good, except when i iterate through the something[], like this :
test *chk;
unsigned long empty = 0;
unsigned long not_empty = 0;
unsigned long i=0;
for (i=0; i< index; i++ )
{
chk = &something[i];
if (!chk->isEmpty())
{
not_empty++;
} else
empty++;
}
cout << "Empty [" << empty << "]" << endl;
cout << "Not Empty [" << not_empty << "]" << endl;
cout << "Total [" << empty + not_empty << "]" << endl;
(LAST UPDATE)
It turned out to be hardware problem - memory. Some of sticks were not working properly together with others. Thanks everyone for suggestions and too bad hardware path isnt in answers o/
(UPDATE)
I get constant number of initialized elements that are not NULL (not_empty). Still have no idea why.
Of course, empty + not_empty = index.
If i comment out data = NULL; in constructor function, i get proper empty/not_empty numbers if i loop through array right after allocating it. but still, after forcing pointers to NULL, i get same constant not_empty value, after looping through array again.
I also had this reworked to plain pointers, using malloc(), and it made no difference, except that it was first the time i noticed pointers to be correct (empty) until i set them.
I did some tests with smaller [index] value (5,500,000,000), and i could not replicate the behavior.
Im using google`s ltcmalloc and allocated memory size suggests, it is using correct [index] size;
Rather than 25000000000, write 25000000000ul. I have suspect your number becomes a 32-bit integer, thus the j < 25000000000 is always true as int(25000000000) = -769803776.
I have this array : BYTE set[6] = { 0xA8,0x12,0x84,0x03,0x00,0x00, } and i need to insert this value : "" int Value = 1200; "" ....on last 4 bytes. Practically to convert from int to hex and then to write inside the array...
Is this possible ?
I already have BitConverter::GetBytes function, but that's not enough.
Thank you,
To answer original quesion: sure you can.
As soon as your sizeof(int) == 4 and sizeof(BYTE) == 1.
But I'm not sure what you mean by "converting int to hex". If you want a hex string representation, you'll be much better off just using one of standard methods of doing it.
For example, on last line I use std::hex to print numbers as hex.
Here is solution to what you've been asking for and a little more (live example: http://codepad.org/rsmzngUL):
#include <iostream>
using namespace std;
int main() {
const int value = 1200;
unsigned char set[] = { 0xA8,0x12,0x84,0x03,0x00,0x00 };
for (const unsigned char* c = set; c != set + sizeof(set); ++c) {
cout << static_cast<int>(*c) << endl;
}
cout << endl << "Putting value into array:" << endl;
*reinterpret_cast<int*>(&set[2]) = value;
for (const unsigned char* c = set; c != set + sizeof(set); ++c) {
cout << static_cast<int>(*c) << endl;
}
cout << endl << "Printing int's bytes one by one: " << endl;
for (int byteNumber = 0; byteNumber != sizeof(int); ++byteNumber) {
const unsigned char oneByte = reinterpret_cast<const unsigned char*>(&value)[byteNumber];
cout << static_cast<int>(oneByte) << endl;
}
cout << endl << "Printing value as hex: " << hex << value << std::endl;
}
UPD: From comments to your question:
1. If you need just getting separate digits out of the number in separate bytes, it's a different story.
2. Little vs Big endianness matters as well, I did not account for that in my answer.
did you mean this ?
#include <stdio.h>
#include <stdlib.h>
#define BYTE unsigned char
int main ( void )
{
BYTE set[6] = { 0xA8,0x12,0x84,0x03,0x00,0x00, } ;
sprintf ( &set[2] , "%d" , 1200 ) ;
printf ( "\n%c%c%c%c", set[2],set[3],set[4],set[5] ) ;
return 0 ;
}
output :
1200