I'm using visual studio and having problem opening this text file I've put it in the folder with all the source code yet i get an "No such file or directory" error. Here's my code
void Game::load_map(const char *filename)
{
int width,height,current;
std::ifstream in(filename);
if(in.fail()){
std::cout << "problem opening the file" <<std::endl;
perror(filename);
}
else
{
in >> width;
in >> height;
for(int i = 0; i < height; i++)
{
std::vector<int> vec;
for(int j = 0; j<width;j++)
{
if(in.eof())
{
std::cout<< "file ends error" << std::endl;;
return;
}
in >> current;
if(current>=0 && current<=1)
{
vec.push_back(current);
}else{
vec.push_back(0);
}
}
map.push_back(vec);
}
}
in.close();
}
and this how I'm calling this function:
load_map("map.map");
You program probably doesn't run in the same directory where the source code is placed, but rather in the Solution\Debug directory.
Either pass a file path relative to this directory to your function
load_map("..\\Project\\map.map");
or move the file you want to open there. Or 3rd option if you're not sure where you program's working directory is, provide a full path
load_map("c:\\Blah\\Blub\\Project\\map.map");
Related
I'm begginer in C++, so may be parts of my code doesn't have sense, sorry.
What I have to do is (C++, Linux, by fstream):
· Receive 3 or more files passed by terminal by:
./executable file1.txt file2.txt file3.txt
· programm a function that read the files file2.txt and file3.txt and copy it to file1.txt (concatenate, don't overwrite)
I don't know how to do it, I don't know anything about fstream, I'm just learning now by myself, so I really need help. Maybe there are similar questions solved in SO, but I don't know how to solve my problem by them.
I attach the code I have. I don't know how to code the function, so it's empty.
Thank you so much.
I try doing:
void concat(char *argv[], int numberoffilesreceived){
char c;
towritethefiles.open(argv[0], ios::app);
for(int i=1; i<numberoffilesreceived; i++){
toreadthefiles.open(argv[i], ios::in);
while(!toreadthefiles.eof()){
toreadthefiles >> c;
towritethefiles<< c;
}
}
}
It compiles but doesn't work, the program freezes when you run it.
and I also try using std::copy by I don't understand how it works.
ifstream toreadthefiles;
ofstream towritethefiles;
void concat(char *argv[], int numberoffilesreceived);
int main(int argc, char *argv[]){
/* 1/2 The code from below to 2/2 it's only to prevent path errors when receiving the files (it works fine) */
const char directory[SIZE]="./";
int count_files=0;
char files[SIZE][SIZE];
for(int i=1; i<argc; i++){
strcpy(files[i], directory);
strcat(files[i], argv[i]);
count_files++;
}
/*2/2 to add ./ to the name files when passed by terminal: ./executable ./file1.txt ./file2.txt ./file3.txt */
/*check if received almost 3 files like required */
if(argc<3){
cout<< "Error, to few files entered" << endl;
getchar();
exit(1);
}
/*pass the files to the concat function*/
for(int i=1; i<argc; i++){
concat(&argv[i], count_files);
}
toreadthefiles.close();
towritethefiles.close();
return 0;
}
void concat(char *argv[], int count_files){
}
I think I see an issue with your concat() function. You are calling concat() for each of the files passed in. Then in the function, you are using count_files to run that loop again for the number of files passed in.
I would consider rewriting concat() function so that it looks like this:
void concat(std::ofstream& outputStream, char* fileToAppend)
{
std::ifstream in(fileToAppend);
if (!in) {
cout << "Error, cannot open file: " << fileToAppend;
return;
}
// Use std::getline to read each line in the input stream,
// then write it to the output stream!
string line;
while (std::getline(in, line)) {
outputStream << line;
}
}
The benefit being that you can reuse the function for appending a single input file to an existing output stream, and you wrap up the check to ensure the file exists (you may want something more sophisticated like returning true/false on the file being appended, or throwing an error, etc.).
In main(), you would replace the code after the check for at least three files with something like:
// Create an output stream with the first file
// ios::out- output flag
// ios::app- append flag
std::ofstream out(argv[1], ios::out | ios::app);
// Make sure the file exists!
if (!out) {
cout << "Error, cannot open file: " << argv[1];
exit(1);
}
// For all other arguments, concat with the first.
for (int i = 2; i < argc; i++) {
concat(out, argv[i]);
}
You can use std::copy with stream iterators, and I've revised my previous suspicion that it would be slow, so here's one way using doing just that with comments in the code.
#include <iostream>
#include <fstream>
#include <vector>
#include <ios>
#include <stdexcept>
void concat(const std::string& destination, const std::vector<std::string>& sources) {
// open the destination file and keep it open until all is done
std::ofstream dest_fs(destination, std::ios_base::binary);
if(!dest_fs)
throw std::runtime_error("Could not write to \"" + destination + "\".");
// loop over the source files
for(const auto& source_file : sources) {
// open the current source file
std::ifstream source_fs(source_file, std::ios_base::binary);
if(!source_fs)
throw std::runtime_error("Could not read from \"" + source_file + "\".");
// copy from source to destination
std::copy(std::istreambuf_iterator<char>(source_fs),
std::istreambuf_iterator<char>(),
std::ostreambuf_iterator<char>(dest_fs));
}
}
int cppmain(std::string program, std::vector<std::string> args) {
if(args.size() < 2) {
std::cout << "USAGE: " << program << " destination_file input_file(s)\n";
return 1;
}
// extract the first argument which is the destination file
std::string destination_file = std::move(args.front());
args.erase(args.begin()); // erase first argument from the vector
try {
// do the concatenation
concat(destination_file, args);
return 0;
} catch(const std::exception& ex) {
std::cerr << program << ": ERROR: " << ex.what() << "\n";
return 1;
}
}
int main(int argc, char* argv[]) {
return cppmain(argv[0], {argv + 1, argv + argc});
}
I have a vector of strings of 2 folder names vector <myClass> vec_fileNames; which I filled by reading from a fileNames.txt which contains 2 lines:
First
Second
ifstream inFile("c:/file names.txt");
if(!inFile)
{
cout << "File Not Found!\n";
inFile.close();
}
else
{
string line;
myClass class;
while (getline(inFile, line))
{
class.setFileName(line);
vec_fileNames.push_back(class);
}
So, at this point my vec_fileName[0].getFileName = First and vec_fileName[1].getFileName = second
Now I wanted to open files inside the folders who's names are in the vector in a loop so I did this:
for(int i = 0; i < vec_fileNames.size(); i++)
{
string fileName = vec_fileNames[i].getFileName();
ifstream inFile("C:/Program Folder\\" + fileName + "goalFile.txt");
if(!inFile)
{
cout << "File Not Found!\n";
inFile.close();
}
else
{
while (getline(inFile, line))
{
//do something
}
}
So far everything is good except for the file not being opened. Is this even something that can be done in c++ or is there an error in the way I'm opening the file?
I created the same folder structure as you have:
C:\
Program Folder
First
goalFile.txt
Second
goalFile.txt
And ran the following simple code. Node that I don't store the filenames in a class, but directly into a vector.
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std; // I'm no fan of this, but you obviously used it.
void loadFileNames(vector<string>& vec_fileNames)
{
ifstream inFile("c:\\file names.txt");
if(!inFile.is_open())
{
cout << "File Not Found!\n";
return;
// inFile.close(); -- no need to close, it is not open!
}
else
{
string line;
while (getline(inFile, line))
{
cout << line << endl;
vec_fileNames.push_back(line);
}
}
}
void openFiles(vector<string>& vec_fileNames)
{
for(int i = 0; i < vec_fileNames.size(); i++)
{
string fileName = vec_fileNames[i];
string path("C:\\Program Folder\\" + fileName + "\\goalFile.txt");
ifstream inFile(path.c_str());
if(!inFile.is_open())
{
cout << "File" << vec_fileNames[i] << "Not Found!" << endl;
}
else
{
cout << "opened file in folder " << vec_fileNames[i] << endl << endl;
string line;
while (getline(inFile, line))
{
cout << line << endl;
}
cout << endl;
}
}
}
int main(int argc, char* argv[])
{
vector<string> fileNames;
loadFileNames(fileNames);
openFiles(fileNames);
return 0;
}
That works, and produces the output:
First
Second
opened file in folder First
First goal file 1
First goal file 2
opened file in folder Second
Second goalfile 1
Second goalfile 2
The lines First goal file 1, etc. are the contents of the two files.
Hi i try to make code in c++. This code only makes text file easy encrypted and save into a new file. And when i compile this code antivirus says, it is virus/spyware Gen:Variant.Kazy.20825. I dont know why it is virus.
Here is my code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
void controlParameters(int argc){ //check if input parameters are ok
if(argc == 1){
cout << "Pokud chcete text zasifrovat, spustte program s parametrem: -enc \"Nazev_souboru.txt\"\n";
cout << "Pokud ho chcete desifrovat, spustte program s parametrem: -dec \"Nazev_souboru.txt\"\n";
}else if(argc > 3){
cout << "Moc parametru. Spustte si program bez parametru.\n";
}else if(argc < 3){
cout << "Chybi jeden parametr. Spustte si program bez parametru.\n";
}else{
cout << "Vsechno vypada zatim dobre\n";
}
}
void encryption(string &file); //encrypt text file
void decryption(string &file); //decrypt text file
bool controlFile(string &file); //check if file can be opened
int main(int argc, char **argv){
controlParameters(argc);
string file;
file = argv[2];
if(controlFile(file)){
}else{
cout << "Soubor nesel nacist." << endl;
return -1;
}
cout << "Ukonceno.\nZmacknete ENTER pro pokracovani..."<<endl;
cin.get();
return 0;
}
bool controlFile(string &file){
ifstream ifs;
ifs.open(file);
if(ifs.is_open()){
ifs.close();
return true;
}else{
ifs.close();
return false;
}
}
void encryption(string &file){
ifstream ifs;
ofstream ofs;
string line;
ifs.open(file);
ofs.open("encrypt.txt");
if(ifs.is_open()){
while(!ifs.eof()){
getline(ifs,line);
int a = line.length();
int i = 0;
while(i < a){
ofs << ((char)(line[i]^100));
}
line.clear();
ofs << "\n";
}
}else{
cout << "Nelze nacist soubor" << endl;
}
}
void decryption(string &file){
ifstream ifs;
ofstream ofs;
string line;
ifs.open(file);
ofs.open("decrypt.txt");
if(ifs.is_open()){
while(!ifs.eof()){
getline(ifs,line);
int a =line.length();
int i = 0;
while(i < a){
ofs << ((char)(line[i]^100));
}
line.clear();
ofs << "\n";
}
}else{
cout << "Nelze nacist soubor" << endl;
}
}
It's good practice to exclude your source-control directories from virus scanners; they can cause performance and locking problems even if there are no false positives while performing source-control actions or compiling (I've seen it happen several times).
So if only to make your programming experience more reliable, disable the virus scanner on those directories.
You may still want to scan the final, released version of your executable to help avoid false positives: after all, even if it's not your fault the virus scanner chokes, it's not a good impression to leave behind on a user.
Antivirus software uses "heuristics" to determine what is a virus and what isn't. So it looks for patterns in the file that does things that it finds suspicious. I can't see anything directly wrong in your code, so I suspect it's a "false-positive". I personally don't like antivirus software, it causes more problems than it solves...
By the way, you could add the "output filename" to your encrypt/decrypt function, and make them one function! ;)
I'm trying to read a text file but nothing is coming out. I feel like maybe It's not linking correctly in my Visual Studio Resources folder but if I double click it - it opens fine in visual studio and it doesn't run into any problems if I test to see if it opens or if it is good. The program compiles fine right now but there's not output. Nothing prints to my command prompt. Any suggestions?
Code
#include <iostream>
#include <iomanip>
#include <fstream>
using namespace std;
int main()
{
char str[100];
ifstream test;
test.open("test.txt");
while(test.getline(str, 100, '#'))
{
cout << str << endl;
}
test.close();
return 0;
}
Text File
This is a test Textfile#Read more lines here#and here
You try to open file by name without path, this means the file shall be in current working directory of your program.
The problem is with current directory when you run your program from VS IDE. VS by default sets current working directory for runnning program to project directory $(ProjectDir). But your test file resides in resources directory. So open() function could not find it and getline() immediately fails.
Solution is simple - copy your test file to project directory. Or copy it to target directory (where your program .exe file is created, typically $(ProjectDir)\Debug or $(ProjectDir)\Release) and change working directory setting in VS IDE: Project->Properties->Debugging->Working Directory, set to $(TargetDir). In this case it will work both from IDE and command line/Windows Explorer.
Another possible solution - set correct path to file in your open() call. For testing/education purposes you could hardcode it, but actually this is not good style of software development.
Not sure if this will help but I wanted to simply open a text file for output and then read it back in. Visual Studio (2012) seems to make this difficult. My solution is demonstrated below:
#include <iostream>
#include <fstream>
using namespace std;
string getFilePath(const string& fileName) {
string path = __FILE__; //gets source code path, include file name
path = path.substr(0, 1 + path.find_last_of('\\')); //removes file name
path += fileName; //adds input file to path
path = "\\" + path;
return path;
}
void writeFile(const string& path) {
ofstream os{ path };
if (!os) cout << "file create error" << endl;
for (int i = 0; i < 15; ++i) {
os << i << endl;
}
os.close();
}
void readFile(const string& path) {
ifstream is{ path };
if (!is) cout << "file open error" << endl;
int val = -1;
while (is >> val) {
cout << val << endl;
}
is.close();
}
int main(int argc, char* argv[]) {
string path = getFilePath("file.txt");
cout << "Writing file..." << endl;
writeFile(path);
cout << "Reading file..." << endl;
readFile(path);
return 0;
}
As input, I have a list of gzipped files. As shown here, I use gzstream to handle them. For practical reasons, I want to open each file and record each stream into a vector. It seems pretty straightforward but I don't manage to make it work. Here is the minimal code:
#include <cstdlib>
#include <iostream>
#include <vector>
using namespace std;
#include <gzstream.h>
int main (int argc, char ** argv)
{
size_t i;
vector<string> vInFiles;
vector<igzstream *> vStreams;
string line;
// create the dummy input files
system ("rm -f infile*.gz; for i in {1..2}; do echo \"toto\"${i} | gzip > infile${i}.gz; done");
vInFiles.push_back ("infile1.gz");
vInFiles.push_back ("infile2.gz");
// open each input file
for (i = 0; i < vInFiles.size(); ++i)
{
igzstream inStream;
inStream.open (vInFiles[i].c_str());
if (! inStream.good())
{
cerr << "ERROR: can't open file " << vInFiles[i] << endl;
exit (1);
}
vStreams.push_back (&inStream);
}
// manipulate each input file
for (i = 0; i < vInFiles.size(); ++i)
{
cout << "read first line of file " << vInFiles[i] << endl;
getline (*(vStreams[i]), line);
if (line.empty())
{
cerr << "empty line" << endl;
exit (1);
}
cout << line << endl;
}
// close each input file
for (i = 0; i < vInFiles.size(); ++i)
{
vStreams[i]->close();
}
vStreams.clear();
return 0;
}
This code compiles properly:
$ gcc -Wall test.cpp -lstdc++ -lgzstream -lz
And although it run smoothly, it doesn't read the files properly:
$ ./a.out
read first line of file infile1.gz
empty line
Your stream pointers are invalid after the iteration ends, as the automatic stream object is destroyed then. If you really need that you need to allocate them on the free store (or make igzstream movable).
// std::vector<boost::shared_ptr<igzstream>> for C++03
std::vector<std::unique_ptr<igzstream>> vStreams;
// ...
for (size_t i = 0; i < vInFiles.size(); ++i) {
// boost::shared_ptr<igzstream> inStream = boost::make_shared<igzstream>();
auto inStream = std::unique_ptr<igzstream>(new igzstream);
inStream->open(...);
// ...
vStreams.push_back(inStream);
}
// ...
This is broken; you store a vector of pointers to streams, but you initialize it with a pointer to a locally scoped automatic instance of the stream (inside the for-loop). Once each iteration of the loop completes, that instance is out of scope, and you have a pointer to some crap.
You then use that crap later, and you get crap out.
Use a smart pointer, e.g.
std::vector<boost::shared_ptr<igzstream> > vStreams;
// to initialize
for (i = 0; i < vInFiles.size(); ++i)
{
boost::shared_ptr<igzstream> inStream(new igzstream(vInFiles[i].c_str());
if (!inStream->good())
{
cerr << "ERROR: can't open file " << vInFiles[i] << endl;
exit (1);
}
vStreams.push_back (inStream); // save the smart pointer
}
As mentioned in the comments, I would prefer not to use Boost and I only have gcc 4.1.2. Thus, here is the solution using the free store, thanks to the suggestion of Cat Plus Plus:
// open each input file
for (i = 0; i < vInFiles.size(); ++i)
{
igzstream * pt_inStream = new igzstream;
pt_inStream->open (vInFiles[i].c_str());
if (! pt_inStream->good())
{
cerr << "ERROR: can't open file " << vInFiles[i] << endl;
exit (1);
}
vStreams.push_back (pt_inStream);
}
And:
// close each input file
for (i = 0; i < vInFiles.size(); ++i)
{
vStreams[i]->close();
delete vStreams[i];
}