timegm, mktime changing struct tm - c++

I try to read some dates in format (d-m-Y) from a file. The dates are in pairs and if the second date is equal to '-' then I register that date as a nullptr. Here is the file:
30-05-2009 20-02-2020
12-06-2012 04-01-2017
22-06-2012 26-04-2017
15-03-2006 15-01-2012
25-09-2002 02-02-2006
15-07-2005 -
20-03-2000 23-01-2004
12-01-2012 19-03-2017
14-08-2008 15-08-2008
27-11-2006 18-06-2007
03-10-2006 24-01-2007
20-12-2010 23-04-2018
27-01-2007 02-03-2018
16-10-2013 11-10-2015
09-07-2003 09-10-2014
31-03-2007 28-12-2013
11-01-2012 06-09-2017
15-08-2007 18-03-2011
24-12-2004 19-08-2008
23-11-2009 -
10-05-2000 11-02-2012
26-12-2005 07-04-2007
12-01-2003 04-10-2008
24-03-2004 04-01-2016
31-05-2001 21-01-2002
27-11-2001 21-03-2013
29-09-2007 21-02-2020
13-10-2004 06-04-2015
12-06-2005 07-05-2008
14-03-2001 21-07-2005
23-11-2003 16-01-2017
13-05-2003 15-07-2016
02-12-2006 17-04-2013
20-03-2004 06-08-2014
18-12-2016 10-03-2017
22-01-2000 13-02-2004
02-03-2000 18-12-2015
01-12-2004 31-03-2019
29-04-2006 19-03-2012
14-04-2007 11-03-2015
02-03-2002 13-12-2015
03-12-2001 16-01-2013
10-12-2000 16-05-2015
08-04-2000 04-04-2018
01-02-2008 30-11-2009
30-03-2006 -
08-09-2010 21-02-2017
19-02-2002 15-03-2003
17-09-2007 18-09-2010
23-01-2007 -
Here is my code as well:
#include <ctime>
#include <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
using namespace std;
int main(int argc, char const *argv[]) {
//variables for reading file
string tempDate;
struct tm *entryDate, *exitDate;
ifstream file("dates.txt");
string input;
// read file
if (file.is_open()) {
cout << '\n';
entryDate = new struct tm;
while (getline(file, input)) {
istringstream inputStream(input);
inputStream >> get_time(entryDate, "%d-%m-%Y") >> tempDate;
if (!tempDate.compare("-")) {
exitDate = nullptr;
} else {
istringstream dateStream(tempDate);
exitDate = new struct tm;
dateStream >> get_time(exitDate, "%d-%m-%Y");
// timegm changes strut tm????
cout << "Before: " << exitDate->tm_mday << ' ' << exitDate->tm_mon << ' ' << exitDate->tm_year << "\n";
cout << timegm(entryDate) << ' ' << timegm(exitDate) << boolalpha << ' ' << (timegm(entryDate) > timegm(exitDate)) << "\n";
cout << "After: " << exitDate->tm_mday << ' ' << exitDate->tm_mon << ' ' << exitDate->tm_year << "\n";
if (timegm(entryDate) > timegm(exitDate)) { // if entryDate is after exitDate
cerr << "Error: entryDate is later than exitDate\n";
cout << put_time(entryDate, "%d-%m-%Y") << ' ' << put_time(exitDate, "%d-%m-%Y") << '\n';
continue;
}
}
entryDate = new struct tm;
}
file.close();
} else {
cerr << "Error: Cannot open file\n";
return 1;
}
return 0;
}
At some point I try to check if the first date is bigger than the second one because he first date is a hospital entry date and the second is an exit date. But when i tried to convert the struct tm to time_t so I can compare the dates, I realized that for some inputs the struct had changed after I called the timegm function (it happens with mktime as well). I've seen people having problems with these functions usually because of DST, but I can't see how that affects my program.

Found the solution after I came across an example in linux manpages that used a struct tm variable and had nothing to do with timegm. If anyone has the same problem just initialize the struct tm to all zero bytes like this:
memset(date, 0, sizeof(struct tm));

Related

C++ values from struct creating newlines in CSV file

I am very new to C++, and currently am attempting to create a simple user interface which will do the following:
Check if a CSV file already exists with the given name
Create that file if it does not exists, and write the headers
Ask user for information, store in struct
Write data to CSV file when done
The issue I am facing is that when the program ends, and writes the data to the CSV file it creates newlines for each struct variable I am writing. I would like the program to just write all data on one line with comma separated format.
Example code:
struct.h
#ifndef struct_h
#define struct_h
#include "string"
namespace RB
{
struct Values
{
std::string event;
std::string town;
std::string state;
std::string date;
};
}; // namespace
#endif /* struct_h */
create.h
#ifndef create_h
#define create_h
#include <cstdio>
#include <ctime>
#include <iostream>
#include <fstream>
namespace RB
{
int createFile()
{
time_t t = time(nullptr); // the current time
struct tm gmt = *gmtime(&t); // structured time in GMT
const int year = 1900 + gmt.tm_year;
static const char *filename = "results_";
if (std::ifstream((filename + std::to_string(year) + ".csv").c_str()))
{
std::cout << "File Found, appending to file " << (filename + std::to_string(year) + ".csv").c_str() << std::endl;
}
else
{
std::cout << "No file with name " << (filename + std::to_string(year) + ".csv").c_str() << "\ncreating file...\n" << std::endl;
std::ofstream ofile((filename + std::to_string(year) + ".csv").c_str());
ofile << "Event" << ","
<< "Town" << ","
<< "State" << ","
<< "Date" << "\n";
ofile.flush();
ofile.close();
};
return 0;
};
}
#endif /* create_h */
main.cpp
#include <cstdio>
#include <stdlib.h>
#include <iostream>
#include "struct.h"
#include "create.h"
int main()
{
// Run Create before continuing
int c = RB::createFile();
struct RB::Values revent;
// Get Event Name
std::cout << "Starting to enter data for race event...\n" << std::endl;
std::cout << "What was the name of the event: ";
std::cin >> revent.event;
// Get Event Town
std::cout << "What town was the race run in: ";
std::cin >> revent.town;
// Get Event City
std::cout << "What state was the race run in: ";
std::cin >> revent.state;
// Get Event Date
std::cout << "When was the race run: ";
std::cin >> revent.date;
time_t t = time(nullptr); // the current time
struct tm gmt = *gmtime(&t); // structured time in GMT
const int year = 1900 + gmt.tm_year;
static const char *filename = "results_";
if (std::ifstream((filename + std::to_string(year) + ".csv").c_str()))
{
std::ofstream ofile((filename + std::to_string(year) + ".csv").c_str(), std::ofstream::out | std::ofstream::app);
ofile << revent.event << ",";
ofile << revent.town << ",";
ofile << revent.state << ",";
ofile << revent.date;
ofile.close();
};
return 0;
}
Sample Output:
Event,Town,State,Date
CapRock
,Turkey
,Texas
,March 9
I assume this is something simple I am doing wrong, but cannot seem to figure it out on my own.

Assertion failure when writing to a text file using ofstream

I am trying to write some string data to a .txt file that i read from the user but after doing so, the program shuts down instead of continuing and when i check the results inside the .txt file i see some part of the data and then some gibberish, followed by an assertion failure error! Here's the code:
#include "std_lib_facilities.h"
#include <fstream>
using namespace std;
using std::ofstream;
void beginProcess();
string promptForInput();
void writeDataToFile(vector<string>);
string fileName = "links.txt";
ofstream ofs(fileName.c_str(),std::ofstream::out);
int main() {
// ofs.open(fileName.c_str(),std::ofstream::out | std::ofstream::app);
beginProcess();
return 0;
}
void beginProcess() {
vector<string> links;
string result = promptForInput();
while(result == "Y") {
for(int i=0;i <= 5;i++) {
string link = "";
cout << "Paste the link skill #" << i+1 << " below: " << '\n';
cin >> link;
links.push_back(link);
}
writeDataToFile(links);
links.clear(); // erases all of the vector's elements, leaving it with a size of 0
result = promptForInput();
}
std::cout << "Thanks for using the program!" << '\n';
}
string promptForInput() {
string input = "";
std::cout << "Would you like to start/continue the process(Y/N)?" << '\n';
std::cin >> input;
return input;
}
void writeDataToFile(vector<string> links) {
if(!ofs) {
error("Error writing to file!");
} else {
ofs << "new ArrayList<>(Arrays.AsList(" << links[0] << ',' << links[1] << ',' << links[2] << ',' << links[3] << ',' << links[4] << ',' << links[5] << ',' << links[6] << ',' << "));\n";
}
}
The problem lies probably somewhere in the ofstream writing procedure but i can't figure it out. Any ideas?
You seem to be filling a vector of 6 elemenents, with indices 0-5, however in your writeDataToFile function are dereferencing links[6] which is out of bounds of your original vector.
Another thing which is unrelated to your problem, but is good practice:
void writeDataToFile(vector<string> links)
is declaring a function which performs a copy of your vector. Unless you want to specifically copy your input vector, you most probably want to pass a const reference, like tso:
void writeDataToFile(const vector<string>& links)

C++ Save a Struct String into A Text File

In my program, I save high scores along with a time in minutes and seconds. In my code, I currently store this as two ints in a struct called highscore. However, this is a little tedious when it comes to formatting when I display the output. I want to display the times as 12:02 not 12:2. I have a variable already made called string clock throughout my game, it is already formatted with the colon, all I want to do is add that inside my text file.
How can I refactor my code to have a single variable for the timestamp, which will be correctly formatted? I want to be able to write my data into the file by directly calling the structure.
// Used for Highscores
struct highscore
{
char name[10];
int zombiesKilled;
// I would like these to be a single variable
int clockMin;
int clockSec;
char Date[10];
};
// I write the data like this:
highscore data;
// ...
data[playerScore].clockMin = clockData.minutes;
data[playerScore].clockSec = clockData.seconds;
streaming = fopen( "Highscores.dat", "wb" );
fwrite( data, sizeof(data), 1 , streaming);
// ...
It seems that you want to simply just write a C-string or std::string to a file using C's fwrite() function.
This should be quite easy, given that your C-string is in ASCII-conforming format (no Unicode funny business):
//It appears you want to use C-style file I/O
FILE* file = NULL;
fopen("Highscores.dat", "wb");
//std::string has an internal C-string that you can access
std::string str = "01:00";
fwrite(str.c_str(), sizeof(char), sizeof(str.c_str()), file);
//You can also do this with regular C strings if you know the size.
We can also choose to try and use C++-style file I/O for cleaner interfaces.
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
int main() {
std::string str = "00:11";
std::ofstream file("example.txt");
if (file.good()) {
file << str;
std::cout << "Wrote line to file example.txt.\n";
}
file.close();
//Let's check if we actually wrote the file.
std::ifstream read("example.txt");
std::string buffer;
if (read.good())
std::cout << "Opened example.txt.\n";
while(std::getline(read, buffer)) {
std::cout << buffer;
}
return 0;
}
Additionally, there are data types in <chrono> that can prove quite helpful for times like there.
If you want to be able to do this:
file << data_struct;
then it would make sense for you to create an operator overload for std::ostream.
You can experiment with time functions. And reading/writing structures.
The right way however is to use c++ basic file storage instead of dumping binar data.
struct highscore
{
char name[10];
int n;
std::time_t dateTime;
};
int main()
{
int total_seconds = 61;
char buf[50];
sprintf(buf, "minutes:seconds=> %02d:%02d", total_seconds / 60, total_seconds % 60);
cout << buf << endl;
std::time_t timeNow = std::time(NULL);
std::tm timeFormat = *std::localtime(&timeNow);
cout << "Current date/time " << std::put_time(&timeFormat, "%c %Z") << endl;
highscore data;
//write data:
{
FILE *streaming = fopen("Highscores.dat", "wb");
strcpy(data.name, "name1");
data.n = 1;
data.dateTime = std::time(NULL);
fwrite(&data, sizeof(data), 1, streaming);
strcpy(data.name, "name2");
data.n = 2;
data.dateTime = std::time(NULL);
fwrite(&data, sizeof(data), 1, streaming);
fclose(streaming);
}
//read data:
{
FILE *streaming = fopen("Highscores.dat", "rb");
fread(&data, sizeof(data), 1, streaming);
cout << "reading:\n";
cout << data.name << endl;
cout << data.n << endl;
timeFormat = *std::localtime(&data.dateTime);
cout << std::put_time(&timeFormat, "%c %Z") << endl;
cout << endl;
fread(&data, sizeof(data), 1, streaming);
cout << "reading:\n";
cout << data.name << endl;
cout << data.n << endl;
timeFormat = *std::localtime(&data.dateTime);
cout << std::put_time(&timeFormat, "%c %Z") << endl;
cout << endl;
fclose(streaming);
}
return 0;
}

Naming a log file using date and time in C++

So, I want to create a log file for an app I am trying to create and I don't know how to name the log to something like "log/date&time"
Anyway, here is my code:
#include <iostream>
#include <fstream>
#include <time.h>
#include <stdio.h>
#include <sstream>
using namespace std;
int main (int argc, char *argv[])
{
time_t t = time(0);
struct tm * now = localtime( & t );
char buffer [80];
strftime (buffer,80,"%Y-%m-%d.",now); //i think i can't just put "log/%Y-%m-%d." there.
ofstream myfile;
myfile.open ("log/" + buffer); // this is my problem, i can't put the ' "log/" + ' part there
if(myfile.is_open())
{
cout<<"Success"<<std::endl;
}
return 0;
}
You should use std::string which supports concatenation via the overloaded operator+.
std::string buffer(80, '\0');
strftime( &buffer[0], buffer.size(), "some format string", now);
/* ... */
std::ofstream myfile( ("log/" + buffer).c_str() );
// Remove the (..).c_str() part when working with a C++11 conforming
// standard library implementation
you actual question is "why doesnt this work"
myfile.open ("log/" + buffer);
answer - because c++ doesnt support what you want - concatenate a string literal with a char * and return another char *.
do
std::string filetime(buffer);
std::string filename = "log/" + filetime;
open(filename.c_str());
Consider using std:: facilities instead (std::string and std::ostringstream come to mind):
std::ostream& time_digits(std::ostream& out, unsigned int digits)
{ // convenience function: apply width and fill for the next input
return out << std::setw(digits) << std::setfill('0');
}
std::string unique_log_name()
{ // generate unique log name, depending on local time
// example output: "log/2014-04-19.log"
auto now = time(0);
tm *ltm = localtime(&now);
std::ostringstream buffer;
buffer
<< "log/" << time_digits(4) << ltm.tm_year
<< "-" << time_digits(2) << ltm.tm_mon
<< "-" << time_digits(2) << ltm.tm_day;
// could also add these to the name format:
// buffer
// << "-" << time_digits(2) << ltm.dm_hour
// << "-" << time_digits(2) << ltm.tm_min
// << "-" << time_digits(2) << ltm.tm_sec;
buffer << ".log"; // add extension
return buffer.str();
}
void client_code()
{ // construct log stream on unique file name
ofstream myfile{ unique_log_name() };
if(myfile)
{
cout << "Success" << std::endl;
}
}

Copy string until '.' And how to copy only numbers when i know the structure

I have a code that i want it to get input file from command line and create output file with XXX at the end - meanning if intput= "blabla.txt" or "/johny/first/blabla.txt" i till get "blablaXXX.txt" or "/johny/first/blablaXXX.txt"
The second question is that when i find a line i was looking for i want to copy only the numbers (keep in date mode) and the len
Line will be "IT IS HERE time 12:04:56.186, len 000120"
And i want to get in the new file line: 12:04:56.186 120
#include <iostream>
#include <fstream>
using namespace std;
int main( int argc, char* args[] )
{
string inputName=args[1];
ifstream inputName(inputFileName);
////// here i will need to get the output string name some thing like
// string outputFileName=EDITED_INPUT_NAME+"XXX"+".txt";
ofstream outpuName(outputFileName);
while( std::getline( inputName, line ) )
{
if(line.find("IT IS HERE") != string::npos)
// how to make it take only the parts i need??????
outpuName << line << endl;
cout << line << endl;
}
inputName.close();
outpuName.close();
return 0;
}
Does this solve your problem:
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
int main(int argc, char* args[]) {
ifstream inputFile(args[1]);
// Your first problem
string outputFileName(args[1]);
outputFileName.insert(outputFileName.find("."), "XXX");
cout << "Writing to " << outputFileName << endl;
// End of first problem
ofstream outputFile(outputFileName.c_str());
string line;
while (getline(inputFile, line)) {
if (line.find("IT IS HERE") != string::npos) {
// Your second problem
string::size_type time_start = line.find("time ") + 5;
string::size_type time_end = line.find(",", time_start);
cout << time_start << " " << time_end << endl;
string time = line.substr(time_start, time_end - time_start);
string::size_type len_start = line.find("len ") + 4;
string::size_type len_end = line.find(" ", len_start);
if (len_end != string::npos)
len_end += 4;
int len = atoi(line.substr(len_start, len_end - len_start).c_str());
// End of second problem
outputFile << time << " " << len << endl;
cout << time << " " << len << endl;
}
}
inputFile.close();
outputFile.close();
return 0;
}
Example input:
sdfghjk sdfghjk fghjkl
IT IS HERE time 12:04:56.186, len 000120
usjvowv weovnwoivjw wvijwvjwv
IT IS HERE time 12:05:42.937, len 000140
Example output:
12:04:56.186 120
12:05:42.937 140
The code could look nicer with std::regex and auto, but as this wasn't tagged with C++11, I held back.