I have 2 files: main.cpp and parser.hpp
I am returning vector<vector> from a member function in class in parser.hpp. However it seems I am not getting anything in my main.cpp from the return value because when I print its size I get 0.
This is my main.cpp:
#include <vector>
#include <cstring>
#include <fstream>
#include <iostream>
#include "parser.hpp"
using namespace std;
int main()
{
ifstream file;
file.open("test.csv");
csv obj;
obj.parse(file);
obj.print_parsed_csv(file);
vector<vector<string>> parsed_csv_data = obj.parse(file);
cout << parsed_csv_data.();
cout << parsed_csv_data.size();
for (int i = 0; i < parsed_csv_data.size(); i++)
{
for (int j = 0; j < parsed_csv_data[i].size(); j++)
cout << parsed_csv_data[i][j] << '\t';
cout << endl;
}
}
This is my parser.hpp
using namespace std;
class csv
{
public:
vector<vector<string>> parse(ifstream &file)
{
string str;
vector<vector<string>> parsed_data;
while (getline(file, str))
{
vector<string> parsed_line;
while (!str.empty())
{
int delimiter_pos = str.find(',');
string word = str.substr(0, delimiter_pos);
// cout << word << " ";
if (delimiter_pos == -1)
{
parsed_line.push_back(word);
break;
}
else
{
str = str.substr(delimiter_pos + 1);
// cout << str << endl;
parsed_line.push_back(word);
}
}
parsed_data.push_back(parsed_line);
}
return parsed_data;
}
void print_parsed_csv(ifstream &file)
{
vector<vector<string>> parsed_csv_data = parse(file);
cout << parsed_csv_data.size();
for (int i = 0; i < parsed_csv_data.size(); i++)
{
for (int j = 0; j < parsed_csv_data[i].size(); j++)
cout << parsed_csv_data[i][j] << '\t';
cout << endl;
}
}
};
I am getting correct cout output in parse() only. print_parsed_csv() in parser.hpp and the cout in main.cpp both are giving 0 as the variable's size.
How do I resolve this?
The first time you call obj.parse the stream object is read from until you get to the end of the file. You need to either reopen the file or reset file to point back to the beginning of the file after reading from it.
You pass the same file variable to each of the three functions below but only the first one works. The first call to obj.parse moves where file is pointing in the input file. When obj.parse exits the first time, file is pointing to the end of the file so when it's used in the subsequent 2 calls, there's nothing to read.
obj.parse(file); // <-- this works fine
obj.print_parsed_csv(file); // <-- this fails
vector<vector<string>> parsed_csv_data = obj.parse(file);fails
// ^^^^^^^^^- this fails
See this question for answers on how to reset the ifstream to the beginning of the file.
Hi I need to find second to last word in a string. Right now below program is printing the last one.
#include <iostream>
#include <string>
using namespace std;
int main() {
string text{"some line with text"};
// find last space, counting from backwards
int i = text.length() - 2; // last character
while (i != 0 && !isspace(text[i]))
{
--i;
}
string lastword = text.substr(i+1); // +1 to skip leading space
cout << lastword << endl;
return 0;
}
Output: (Printing last word)
text
You can split the string into words and hold the previous word before saving the current word.
#include <iostream>
#include <string>
#include <sstream>
int main() {
std::string text{"some line with text"};
std::stringstream ss(text);
std::string previousword, lastword, newword;
while (ss >> newword) {
previousword = lastword;
lastword = newword;
}
std::cout << previousword << std::endl;
return 0;
}
Also note that using using namespace std; is discouraged.
You don't need any loops. Just add error checking:
int main() {
std::string text{ "some line with text" };
std::size_t pos2 = text.rfind(' ');
std::size_t pos1 = text.rfind(' ', pos2-1);
std::cout << text.substr(pos1+1, pos2-pos1-1) << std::endl;
return 0;
}
Just keep counting spaces until you arrive to the word you want or use a stringstream as MikeCAT proposed.
Here there is a function that finds any last word number without having to copy the entire string in a stringstream:
#include <iostream>
#include <string>
using std::string;
using std::cout;
using std::endl;
string getNLastWord(string text, int n)
{
bool insideAWord = false;
int wordNum = 0;
int wordEnd = -1;
for(int i = text.size() - 1; i > 0; i--)
{
if(text[i] != ' ' && !insideAWord)
{
wordNum++;
insideAWord = true;
}
else if(text[i] == ' ')
{
insideAWord = false;
}
if(wordNum == n)
{
wordEnd = i;
break;
}
}
if(wordEnd == -1)
{
cout << "There are no " << n << " words from right." << endl;
}
else
{
int wordStart;
for(wordStart = wordEnd; wordStart > 0; wordStart--)
{
if(text[wordStart] == ' ')
{
wordStart++;
break;
}
}
return text.substr(wordStart,wordEnd+1-wordStart);
}
return "";
}
int main() {
string text = "some text";
cout << getNLastWord(text,2);
return 0;
}
I am doing an assignment (.csv-parser) for uni. While trying to run the code after compilation it returns a SegFault 11.
This is my code:
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
int main (int argc, char** argv) {
string line;
string buffer;
vector<vector<string> > database;
vector<string> dataset;
//bool start = true;
ifstream denkmaeler;
denkmaeler.open(argv[1]);
ifstream denkmal;
denkmal.open(argv[1]);
int semic = 1;
//int semic2 = 1;
int zaehler = 0;
if (denkmal.is_open()){
(getline(denkmal, buffer));
for (int i = 0; i < buffer.length(); i++ ){
if(buffer[i] == ';'){
semic++;}
}
}
denkmal.close();
if(denkmaeler.is_open()) {
//if (counter < 1) {
while (getline(denkmaeler, buffer));
if (line.back() == *argv[2]) {
line += argv[2];
stringstream ss(line);
while (getline(ss, line, *argv[2])) {
dataset.push_back(line);
database.push_back(dataset);
dataset.clear();
}
}
}
for (int x=0, y=semic; x < semic; y=database.size(), x++, y++){
if (x > semic){
x=0;
cout << '\n' << "-------------------------------" << '\n' << endl;
}
if (database[y][0].length() == 0){
database[y][0] = "not available";
}
cout << database[x][0] << " : " << database[y][0] << endl;
}
}
If someone would be able to point out my mistake I would be very thankful. I read some posts pointing out that the problem could be an array but I am not sure how that could be.
For segmentation error, it is best to use a debugging tool which can exactly show you where the error is (which line)!
I am using gdb, i recommend you to google it
I've been looking at this for a while in the debugger while Googling around, but I think I've stumbled upon some C++ behavior that I'm not familiar with. I'm going to give a quick outline on what I'm doing and what/where the problem is. I'll put code block below.
The rough outline of what's happening is:
Created a custom class (LogReader) to handle a single log file.
LogReader contains a pointer to an ifstream (ifstream *log_file)
The ifstream is used with getline() in the constructor, this works fine.
The LogReader is placed in a vector.
The code below for main.cpp is using the LogReader directly (without the vector). The segfault occurs in both cases.
LogReader.advance() is called. getline() is used in this function. The segfault occurs here (commented in LogReader.cpp).
Thanks for any help on what C++ behaviors I'm missing that might be causing this!
EDIT: Not placing the LogReader into a vector removes the segfault (failing elsewhere now, but not a problem). The change is commenting the following line out in main.cpp
readers.push_back(&label_reader);
I guess now the question is why using std::vector is causing this problem.
LogReader.h
#ifndef LOGREADER
#define LOGREADER
using namespace std;
class LogReader {
private:
LogReader(){} // private default constructor
public:
ifstream *log_file; // file the log is read from
vector<int> val_locations; // offsets in line for values
string next_line; // next line from the file
int current_time; // time for most recent reading
string current_line;
int next_time; // what is the next time in the file
vector<string> current_vals; // what the current vals are
LogReader(string log_loc, vector<int> offsets); // given a file to start on
bool advance(int new_time); // advance the log reader, return true if advanced
bool has_more(); // is there more in the log
};
#endif
LogReader.cpp
// c++ imports
#include <boost/algorithm/string.hpp>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>
// my imports
#include "LogReader.h"
#include "functions.h"
using namespace std;
LogReader::LogReader(string log_loc, vector<int> offsets){
// make the file reader
ifstream lf(log_loc);
log_file = &lf;
// pull out the first line
getline(*log_file, current_line);
cout << current_line << endl;
// get the set of current values
val_locations = offsets;
for(int i = 0; i < val_locations.size(); i++) {
current_vals.push_back(get_line_part(current_line,
val_locations.at(i)));
}
// get the current time
current_time = stoi(get_line_part(current_line, 0));
// pull down the next line
getline(*log_file, next_line);
cout << next_line << endl;
// get the next time
next_time = stoi(get_line_part(next_line, 0));
}
bool LogReader::advance(int new_time){
if(new_time < next_time)
return false; // nothing to do, current still good
cout << "can check time" << endl;
// update the time and values
current_time = next_time;
current_line = next_line;
current_vals.clear();
cout << "can do housekeeping" << endl;
for(int i = 0; i < val_locations.size(); i++) {
current_vals.push_back(get_line_part(next_line,
val_locations.at(i)));
}
cout << "can push in new values" << endl;
// move the line
next_line.clear();
if(!getline(*log_file, next_line)) { // **SEGFAULT**
// no more lines
cout << "no more lines" << endl;
next_line.clear();
next_time = -1;
return true;
}
cout << "got the line" << endl;
// update the time as well
next_time = stoi(get_line_part(next_line, 0));
return true;
}
bool LogReader::has_more(){
return next_time != -1;
}
main.cpp
// c imports
#include <time.h>
// c++ imports
#include <algorithm>
#include <boost/algorithm/string.hpp>
#include <boost/date_time.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/filesystem.hpp>
#include <fstream>
#include <iostream>
#include <string>
#include <sstream>
#include <vector>
// my imports
#include "LogReader.h"
#include "functions.h"
// custom shorter namespaces
namespace bfs = boost::filesystem;
// used namespaces
using namespace std;
void update_line(int *current_time, string *current_line,
ifstream *current_file){
if(!getline(*current_file, *current_line)){
*current_time = -1;
current_line->clear();
return;
}
try {
*current_time = stoi(get_line_part(*current_line, 0));
} catch (int e) {
cout << "update line, bad stoi on time" << endl;
cout << *current_line << endl;
throw e;
}
}
void update_vals(vector<float*> vals, string line) {
for(int i = 0; i < vals.size(); i++) {
// offset for fact that first two are time and sensor
try {
*(vals.at(i)) = stof(get_line_part(line, 2 + i));
} catch (int e) {
cout << "update_vals, bad stof for " << i << endl;
cout << line << endl;
throw e;
}
}
}
string get_correct_file(string name, vector<string> options) {
for(int i =0; i < options.size(); i++) {
string option = options.at(i);
if(boost::algorithm::contains(option, name)){
return option;
}
}
return string("");
}
int main(int argc, char* argv[]) {
// open the base dir
bfs::path base_dir("log/");
if(!bfs::exists(base_dir) && !bfs::is_directory(base_dir)){
cout << "Bad base directory" << endl;
return 1;
}
// create a vector of the possible traces
vector<string> traces;
for(bfs::directory_iterator iter(base_dir);
iter != bfs::directory_iterator(); iter++) {
stringstream trace_path;
trace_path << iter->path().string();
traces.push_back(trace_path.str());
}
int trace_index = user_choose_option(traces);
// load that directory
bfs::path trace_dir(traces.at(trace_index));
if(!bfs::exists(base_dir) && !bfs::is_directory(base_dir)){
cout << "Selected a bad trace directory" << endl;
return 1;
}
// get the image directory
cout << "loading image directory" << endl;
string img_path_string = trace_dir.string();
stringstream img_path_stream;
img_path_stream << img_path_string << "/img/";
bfs::path img_dir(img_path_stream.str());
if(!bfs::exists(img_dir) && !bfs::is_directory(img_dir)){
cout << "no image directory" << endl;
return 1;
}
// get image list, ends up in sorted order from naming conventions
cout << "getting image paths" << endl;
vector<string> image_paths;
for(bfs::directory_iterator iter(img_dir);
iter != bfs::directory_iterator(); iter++) {
stringstream image_path;
image_path << iter->path().string();
image_paths.push_back(image_path.str());
}
// get the data traces
cout << "loading data traces" << endl;
vector<string> log_paths;
vector<string> label_paths;
string trace_path_string = trace_dir.string();
for(bfs::directory_iterator iter(trace_path_string);
iter != bfs::directory_iterator(); iter++) {
string cur_file = iter->path().string();
cout << cur_file << endl;
if(boost::algorithm::contains(cur_file, "label-")) {
label_paths.push_back(cur_file);
} else if(boost::algorithm::contains(cur_file, "log-")) {
log_paths.push_back(cur_file);
}
}
cout << endl;
// temp for reading in line parts
// istringstream temp;
cout << "getting log readers" << endl;
// choose the label file to use, get first line
int label_index = user_choose_option(label_paths);
vector<int> label_offsets;
label_offsets.push_back(1);
LogReader label_reader(label_paths.at(label_index), label_offsets);
/*
ifstream label_file(label_paths.at(label_index));
string label_line;
getline(label_file, label_line);
int label_time;
temp.clear();
temp.str(get_line_part(label_line, 0));
temp >> label_time;
string label_current = get_line_part(label_line, 1);
*/
/*
// get the accel
string accel_path = get_correct_file("accel", log_paths);
vector<int> accel_offsets;
accel_offsets.push_back(2);
accel_offsets.push_back(3);
accel_offsets.push_back(4);
LogReader accel_reader(accel_path, accel_offsets);
*/
vector<LogReader*> readers;
vector<bool> updated;
readers.push_back(&label_reader);
updated.push_back(true);
// readers.push_back(&accel_reader);
// updated.push_back(true);
int l_time = current_time_min(readers);
while(label_reader.has_more() ){ // || accel_reader.has_more()) {
// figure out what time to advance to
int n_time;
cout << label_reader.has_more() << endl;
if(same_current_time(readers)) {
n_time = next_time_min(readers);
} else {
n_time = current_time_nextmin(readers);
}
cout << n_time << endl;
label_reader.advance(n_time);
cout << label_reader.current_line << endl;
/*
// advance all the readers
for(int i = 0; i < readers.size(); i++) {
cout << "loop " << i << endl;
// keep track of which values updated
readers.at(i);
cout << "can get from vector" << endl;
bool advanced = readers.at(i)->advance(n_time);
cout << advanced << endl;
if(advanced) {
updated.at(i) = true;
} else {
updated.at(i) = false;
}
}
// sanity check printing
for(int i = 0; i < readers.size(); i++) {
cout << readers.at(i)->current_line << endl;
}
*/
// deal with statistics here
}
/*
ifstream accel_file(accel_path);
string accel_line;
getline(accel_file, accel_line);
int accel_time;
temp.clear();
temp.str(get_line_part(accel_line, 0));
temp >> accel_time;
float accel_current_x = stof(get_line_part(accel_line, 2));
float accel_current_y = stof(get_line_part(accel_line, 3));
float accel_current_z = stof(get_line_part(accel_line, 4));
vector<float*> accel_vals;
accel_vals.push_back(&accel_current_x);
accel_vals.push_back(&accel_current_y);
accel_vals.push_back(&accel_current_z);
// get the sprox
string sprox_path = get_correct_file("sprox", log_paths);
ifstream sprox_file(sprox_path);
string sprox_line;
getline(sprox_file, sprox_line);
int sprox_time;
temp.clear();
temp.str(get_line_part(sprox_line, 0));
temp >> sprox_time;
float sprox_current = stof(get_line_part(sprox_line, 2));
vector<float*> sprox_vals;
sprox_vals.push_back(&sprox_current);
// get the lprox
string lprox_path = get_correct_file("lprox", log_paths);
ifstream lprox_file(lprox_path);
string lprox_line;
getline(lprox_file, lprox_line);
int lprox_time;
temp.clear();
temp.str(get_line_part(lprox_line, 0));
temp >> lprox_time;
float lprox_current = stof(get_line_part(lprox_line, 2));
vector<float*> lprox_vals;
lprox_vals.push_back(&lprox_current);
// get the light
string light_path = get_correct_file("light", log_paths);
ifstream light_file(light_path);
string light_line;
getline(light_file, light_line);
int light_time;
temp.clear();
temp.str(get_line_part(light_line, 0));
temp >> light_time;
float light_current = stof(get_line_part(light_line, 2));
vector<float*> light_vals;
light_vals.push_back(&light_current);
*/
// int time_current = min(label_time, min(sprox_time,
// min(lprox_time, min(accel_time,
// light_time))));
/*
// variables for processing here
int total_time = 0;
map<string, int> label_counts;
while(label_time != -1 || accel_time != -1 || sprox_time != -1
|| lprox_time != -1 || light_time != -1) {
time_current++;
if(label_time != -1 && time_current > label_time) {
update_line(&label_time, &label_line, &label_file);
if(label_line.size() > 0) // if last label, don't overwrite
label_current = get_line_part(label_line, 1);
}
if(accel_time != -1 && time_current > accel_time) {
update_line(&accel_time, &accel_line, &accel_file);
if(accel_line.size() > 0) // if last line, don't overwrite
update_vals(accel_vals, accel_line);
}
if(sprox_time != -1 && time_current > sprox_time) {
update_line(&sprox_time, &sprox_line, &sprox_file);
if(sprox_line.size() > 0) // if last line, don't overwrite
update_vals(sprox_vals, sprox_line);
}
if(lprox_time != -1 && time_current > lprox_time) {
update_line(&lprox_time, &lprox_line, &lprox_file);
if(lprox_line.size() > 0) // if last line, don't overwrite
update_vals(lprox_vals, lprox_line);
}
if(light_time != -1 && time_current > light_time) {
update_line(&light_time, &light_line, &light_file);
if(light_line.size() > 0) // if last line, don't overwrite
update_vals(light_vals, light_line);
}
// Processing happens here
total_time++;
if(label_counts.count(label_current) == 0)
// not in map
label_counts[label_current] = 0;
label_counts[label_current]++;
}
// post processing happens here
cout << "Labels Counts:" << endl;
for(map<string, int>::iterator it = label_counts.begin();
it != label_counts.end(); it++) {
cout << it->first << " -> " << it->second << " -> ";
cout << 1.0 * it->second / total_time << endl;
}
*/
}
Your program exhibits undefined behavior since you are using a pointer to an object that has been deleted.
ifstream lf(log_loc);
log_file = &lf;
if gets deleted when the constructor returns and you are still holding on to a pointer to the object.
Change log_file to an object instead of a pointer.
Hi I'm working on a program that reads in two files and i want to display the files content in their own columns for ex.
File1 File2
Time data Time data
I'm not quit sure how to create columns as such, I already have the code to read in the files and perform the functions needed its the output I'm stumped on. If anyone has any suggestions or help that would be awesome. Thanks! PS. This is NOT Homework Related.
I would do something like this:
#include <iostream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <string>
using namespace std;
int readLines(const std::string& fileName1, const std::string& fileName2)
{
string line1;
string line2;
ifstream file1 (fileName1.c_str());
ifstream file2 (fileName2.c_str());
if (file1.is_open() && file2.is_open())
{
cout << setw(20) << left << "File1" << "File2" << endl;
bool done;
done = file1.eof() && file2.eof();
while (!done)
{
getline (file1, line1);
getline (file2, line2);
line1.erase(std::remove(line1.begin(), line1.end(), '\n'), line1.end());
line2.erase(std::remove(line2.begin(), line2.end(), '\n'), line2.end());
cout << setw(20) << left << (file1.eof() ? "" : line1) << (file2.eof() ? "" : line2) << endl;
done = file1.eof() && file2.eof();
}
file1.close();
file2.close();
}
else
{
cout << "Unable to open some file";
}
return 0;
}
int main ()
{
std::string fileName1("example1.txt");
std::string fileName2("example2.txt");
readLines(fileName1, fileName2);
return 0;
}
It really depends on what tools you are planning to use...
You can use some version of "curses" (a library with console manipulation functions such as "go to this position", "print text in green", etc), and then just walk around the screen as you like.
Or you could just read the files into separate variables and then print from each file in a loop. This requires no special codding. Just use an array or vector for the files themselves and the data you read from them.
Something like this:
const int nfiles = 2;
const char *filenames[nfiles] = { "file1.txt", "file2.txt" };
ifstream files[nfiles];
for(int i = 0; i < nfiles; i++)
{
if (!files[i].open(filenames[i]))
{
cerr << "Couldn't open file " << filenames[i] << endl;
exit(1);
}
}
bool done = false;
while(!done)
{
int errs = 0;
std::string data[nfiles];
for(int i = i < nfiles; i++)
{
if (!(files[i] >> data[i]))
{
errs++;
data[i] = "No data";
}
}
if (errs == nfiles)
{
done = true;
}
else
{
for(int i = 0; i < nfiles; i++)
{
... display data here ...
}
}
}