I am having some trouble with sprintf and fstream functions in order to create new text files for a POS program/check whether the file already exists. I don't know if i am doing something wrong because the same set of functions works fine in other places in my code...
This particular section of code is taking input from the user to create a details file, the name is made up of the first and last name details that were entered into the system. For some reason the new file is not being created. When I step through the program I can see that the custDetC variable is being filled with the correct data. I have also included the file existence check as it may or may not have something to do with the issue at hand...
Tony Mickel
sprintf(custDetC,"%s%s.txt", firstName.c_str(), lastName.c_str());
cout << custDetC << endl;
FileEX = FileExists(custDetC);
if (FileEX == true)
{
fopen_s(&custDetF,custDetC, "rt");
fprintf(custDetF, "%s %s\n", firstName, lastName);
fprintf(custDetF, "$d\n", phoneNo);
fprintf(custDetF, "%s $s\n", unitHouseNum, street);
fprintf(custDetF, "%s %s %d", suburb, state, postCode);
fclose(custDetF);
}
else
{
char *buf = new char[100];
GetCurrentPath(buf);
cout << "file " << custDetC << " does not exist in " << buf << endl;
}
}
bool FileExists(char* strFilename)
{
bool flag = false;
std::fstream fin;
// _MAX_PATH is the maximum length allowed for a path
char CurrentPath[_MAX_PATH];
// use the function to get the path
GetCurrentPath(CurrentPath);
fin.open(strFilename, ios::in);
if( fin.is_open() )
{
//cout << "file exists in " << CurrentPath << endl;
flag = true;
}
else
{
//cout << "file does not exist in " << CurrentPath << endl;
flag = false;
}
fin.close();
return flag;
}
You seem to be opening the file for reading, but you need to open it for writing.
Instead of "rt" use "wt" in fopen_s()
Related
Im working on a system, where i want to incooporate a log in form of a .txt file.
This file should be created everytime the program is started, and will in the future be written to, when i've created all my errorcodes.
To keep these log files unique, i wanted to use timestamp. For getting these stamps i've used the following code:
string GetDateStamp() {
time_t now = time(0);
struct tm tstruct;
char stamp[80];
tstruct = *localtime(&now);
strftime(stamp, sizeof(stamp), "%Y-%m-%d-%X", &tstruct);
return stamp;
}
This function is then called in another function, where i check if the dir for the log is created, if it is not, then it creates it.
void OpenNewLogFile(string& filepath)
{
string datestamp;
string logpath = filepath + "Log\\";
if (_mkdir(logpath.c_str()) == 0)
{
cout << "dir created" << endl;
}
else if(_mkdir(logpath.c_str()) == EEXIST)
{
cout << "dir already exists" << endl;
}
else if (_mkdir(logpath.c_str()) == ENOENT)
{
cout << "path could not be found" << endl;
}
ofstream outfile;
datestamp = GetDateStamp();
string createFile="";
createFile = logpath + datestamp + ".txt";
cout << createFile << endl;
outfile.open(createFile);
}
The code is present in a header file, and called upon from my main cpp.
The output i get now, is the path as follows:
C:...\Log\2020-08-10-15:59:22.txt
but no .txt file appears in my log dir.
Maybe the solution is right in front of me, but sadly i cannot see it.
Hope some of you can help me out :-)
IN IOS app, module written in C++ I am writing my data (map of basic strings and integers) to a text file. Using following method:
bool Recognizer::saveMap(const char * s)
{
if(trainingData.model && !trainingData.model.empty()) {
const string filename = string(s);
std::ofstream file(s, ios_base::trunc );
try{
if(! file.is_open())
{
file.open(s);
}
for (map<String,int>::iterator it=trainingData.idMap.begin(); it!=trainingData.idMap.end(); ++it)
{
cout << it->second << " " << it->first << endl;
file << it->first << endl << it->second << endl;
}
file.close();
}
catch(cv::Exception & e){
if(file.is_open())
file.close();
int code = e.code;
string message = e.err;
cerr << "cv::Exeption code: " << code << " " << message << endl;
return false;
}
std::streampos fileLength = iosFileSize(s);
cout << "Saved map to: " << filename << " length: " << fileLength << endl;
return true;
}
return false;
}
My contains one entry and console output indicates that two lines: string, string representing number have been written to my file.
Subsequent opening file for reading and reading using getline or using stream operator indicates that file is empty:
bool Recognizer::loadMap(const char * s)
{
std::streampos fileLenght = iosFileSize(s);
std::ifstream file(s, ios::in);
try{
if(file.is_open())
{
string name;
string lineName;
string lineTag;
int tag;
int count = 0;
while(getline(file,name))
{
if(getline(file,lineTag))
{
tag = stoi(lineTag,0,10);
count++;
cout << tag << " " << name << endl;
trainingData.idMap[name]=tag;
trainingData.namesMap[tag]=name;
}
}trainingData.personsCount=count;
file.close();
}
}
catch(cv::Exception & e){
if(file.is_open())
file.close();
int code = e.code;
string message = e.err;
cerr << "cv::Exeption code: " << code << " " << message << endl;
return false;
}
cout << "Loaded map from: " << s << " lenght: "<< fileLenght << endl;
return true;
}
I also copied from one of stackoverflow answers method returning file lenght and using it to verify lenghth of the file after write operation:
std::streampos iosFileSize( const char* filePath ){
std::streampos fsize = 0;
std::ifstream file( filePath, std::ios::binary );
fsize = file.tellg();
file.seekg( 0, std::ios::end );
fsize = file.tellg() - fsize;
file.close();
return fsize;
}
The file path passed to saveMap and loadMap seems to be legit. With path that the app could not write to, attempt to write caused exception.
There are no errors returned by write operation but both, attempts to read and iosFileSize() indicate that file is empty.
I am not sure if i need call file.open() and file.close() or file is open and closed automatically when output stream is created and later goes out of scope.
I experimented with those with the same result ( call to file.is_open returns true so the block calling file.open() is skipped.
What am I doing wrong?
I appreciate all responses.
It does not seem like you call file.flush(); anywhere in Recognizer::saveMap() after writing to the file stream. std::ofstream::flush() saves changes you've made to the file. Add file.flush(); between when you make changes to the code and when you close the file. See if that remedies your issue.
I also had the same issue. Using file.flush() everytime after you insert to a file can save your file.
However if you insert something like this, say,
file << "Insert This"; You will need to add file.flush().
But some people have issues, like if you just insert file << "Insert This" << endl; , this works fine. The key point here is that, std::endl calls flush() everytime it is used internally. you can say it is a shortend form of "\n" + flush().
I believe from looking at your code that you are overwriting your data when you open the file in the second program you should be using something like this.
std::fstream fs;
fs.open ("test.txt", ios::app)
instead of doing the ios::in
I am new to Protocol Buffers and inexperienced with C++, I am trying to complete the tutorial at https://developers.google.com/protocol-buffers/docs/cpptutorial
I've created the proto file mentioned in the tutorial and gotten addressbook.pb.h and addressbook.pb.cc from this proto. I am trying to follow the segment "Writing A Message", so I copied and pasted the following code from the tutorial. I immediately run into an issue in the main function, which I'll explain below:
#include <iostream>
#include <fstream>
#include <string>
#include "addressbook.pb.h"
using namespace std;
// This function fills in a Person message based on user input.
void PromptForAddress(tutorial::Person* person) {
cout << "Enter person ID number: ";
int id;
cin >> id;
person->set_id(id);
cin.ignore(256, '\n');
cout << "Enter name: ";
getline(cin, *person->mutable_name());
cout << "Enter email address (blank for none): ";
string email;
getline(cin, email);
if (!email.empty()) {
person->set_email(email);
}
while (true) {
cout << "Enter a phone number (or leave blank to finish): ";
string number;
getline(cin, number);
if (number.empty()) {
break;
}
tutorial::Person::PhoneNumber* phone_number = person->add_phone();
phone_number->set_number(number);
cout << "Is this a mobile, home, or work phone? ";
string type;
getline(cin, type);
if (type == "mobile") {
phone_number->set_type(tutorial::Person::MOBILE);
} else if (type == "home") {
phone_number->set_type(tutorial::Person::HOME);
} else if (type == "work") {
phone_number->set_type(tutorial::Person::WORK);
} else {
cout << "Unknown phone type. Using default." << endl;
}
}
}
// Main function: Reads the entire address book from a file,
// adds one person based on user input, then writes it back out to the same
// file.
int main(int argc, char* argv[]) {
// Verify that the version of the library that we linked against is
// compatible with the version of the headers we compiled against.
GOOGLE_PROTOBUF_VERIFY_VERSION;
if (argc != 2) {
cerr << "Usage: " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
return -1;
}
tutorial::AddressBook address_book;
{
// Read the existing address book.
fstream input(argv[1], ios::in | ios::binary);
if (!input) {
cout << argv[1] << ": File not found. Creating a new file." << endl;
} else if (!address_book.ParseFromIstream(&input)) {
cerr << "Failed to parse address book." << endl;
return -1;
}
}
// Add an address.
PromptForAddress(address_book.add_person());
{
// Write the new address book back to disk.
fstream output(argv[1], ios::out | ios::trunc | ios::binary);
if (!address_book.SerializeToOstream(&output)) {
cerr << "Failed to write address book." << endl;
return -1;
}
}
// Optional: Delete all global objects allocated by libprotobuf.
google::protobuf::ShutdownProtobufLibrary();
return 0;
}
In the main function the code exits without prompting for any inputs due to this portion:
if (argc != 2) {
cerr << "Usage: " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
return -1;
}
which appears as one of the first few lines in the function, before any inputs are requested. I read that argc will be the number of inputs. I'm confused because I copied and pasted exactly what the tutorial wrote, but it doesn't appear to be running correctly.
That code expects a file name to be passed on the command line, not read from stdin. You've not specified what platform you're on, but you'll do something like my_program.exe C:\some\file\somewhere on Windows or ./my_program /some/file/somewhere on Linux/Mac/Other Unix like OS. If you're running the program from your IDE's run/debug function then you'll need to configure it to pass the name of the file as a command line argument. How to do that will depend on what IDE you're using.
Okay guys, I've tried everything I can think of. I'm passing in a file name into this function. A little context: hash_table is an already initialized and filled vector with key pairs, and the 'value' part of the pair is a Linked List that has the field "bucket_size". When I use cout to check if these fields are actually being accessed, they are; even the debugger lists them as being filed into the output stream. I have flush() and close() in there, but it doesn't write anything to the file. Returns true, indicating no errors in the stream. Anyone have nay ideas?
string line;
std::ofstream ofs;
if(ofs.is_open())
ofs.close();
ofs.open(filename);
if (ofs.is_open())
{
cout << "File Opened" << endl;
for (double i = 0; i < hash_table.capacity(); ++i)
{
ofs << "Bucket Number " << i;
if (hash_table[i].value != NULL)
ofs << " Bucket Size: " << hash_table[i].value->bucket_size << endl;
else
ofs << " Bucket Size: 0" << endl;
ofs.flush();
}
cout << "closing file stream" << endl;
ofs.flush();
ofs.close();
if (ofs.good())
return true;
else
return false;
}
else
{
cout << "File not opened" << endl;
return false;
}
}
You're almost certainly examining the wrong file. Remember that relative paths are relative to the working directory of the process, which is not necessarily the same as where the executable lives on disk.
I compiled and ran it by the console and now it works, with no edits made. It seems my IDE doesn't like something in the code. Regardless, thank you everyone for the response.s
I am trying to read a las file larger then 2GBs (about 15GBs) but ios::fail() flag becomes true in 345th byte. Here is the code below.
void Foo()
{
char* filename = "../../../../../CAD/emi/LAS_Data/AOI.las";
ifstream m_file (filename);
char c;
int count = 0;
if (m_file.is_open())
{
while ( m_file.good() )
{
m_file.get(c);
cout << c << endl;
count++;
}
// Check State
if(m_file.fail())
cout << "File Error: logical error in i/o operation." << endl;
if(m_file.eof())
cout << "Total Bytes Read: " << count << endl;
m_file.close();
}
else
{
cout << "File Error: Couldn't open file: " << endl;
}
}
And the output is:
...
File Error: logical error in i/o operation.
Total Bytes Read: 345
What am I missing?
I'm going to guess that you're using Windows. Windows has a quirk that a Control-Z marks the end of a text file, no matter how large the file actually is. The solution is to open the file in Binary mode.
ifstream m_file (filename, std::ios::binary);