I'm getting a strange error when trying to iterate a Map of Vectors. I'm using the Stanford CS106B class libraries for this project and when I try to compile the code I get an error telling me that "itr has no member named 'first' "
I have tried searching for solutions to this problem and I have found many similar entries but the answers seem to mimic what I'm doing. I'm sure I'm missing something simple...
#include <iostream>
#include <fstream>
#include <string>
#include "console.h"
#include "simpio.h" // for getLine
#include "strlib.h"
#include "vector.h"
#include "queue.h"
#include "map.h"
#include <iterator>
using namespace std;
void CountLetters(ifstream &filename) {
int index=0;
Vector<int> counts;
for (int i=0; i<=26; i++) {
counts.add(0);
}
char c;
while (!filename.eof()) {
c=filename.get();
index=c-'a';
if (index>=0 && index<26) {
c=stringToChar(toLowerCase(charToString(c)));
counts[index]++;
}
}
for (int y=0; y<=26; y++) {
cout << char('a'+y) << ": " << counts[y] << endl;
}
filename.close();
}
Map <string, Vector<char> > assembleSets (ifstream &in, int seed) {
Map <string, Vector<char> > letterSets;
char c;
Vector<char> workingText;
string letterSet;
while(!in.eof()) {
if (workingText.size()<seed) { // Build the intial set of "seed" letters.
c=in.get();
workingText.add(c);
}
else {
c=in.get();
letterSet.clear();
for (int i=0; i<workingText.size()-1; i++) {
letterSet+=workingText[i]; // add the letter to the letter set.
workingText[i]=workingText[i+1]; // move the letter down one in the vector (simulate queue).
}
letterSet+=workingText[seed-1];
workingText[seed-1]=c; // add the newwest letter to the workingText but do not add it to the letter set.
// Check to see if the letter set exists already, if not, add it.
if (!letterSets.containsKey(letterSet)) {
Vector<char> blank;
letterSets.add(letterSet,blank);
letterSets[letterSet].add(c);
}
else {
// Add the next character to the vector of characters for that letter set.
letterSets[letterSet].add(c);
}
}
}
return letterSets;
}
int main() {
ifstream in;
int mSeed =0;
while (true) {
string fileName = getLine("Please enter a file name");
in.open(fileName);
if(in.fail()) cout << "Couldn't open file!" << endl;
else break;
}
// CountLetters(in);
while (true) {
mSeed=getInteger("Enter a seed value: ");
if (mSeed>0&&mSeed<=10) {
break;
} else {
cout << "Please choose a value from 1 to 10." << endl;
}
}
Map<string, Vector<char> > letterSets = assembleSets(in, mSeed);
Map<string, Vector<char> > :: iterator itr;
for (auto& it: letterSets) {
string keys = (it.first);
Vector<char> values = it.second;
}
return 0;
}
Any help would be fantastic! I'm really scratching my head.
It simply means that Map<string, Vector<char> > :: iterator.
Using std::map instead of Map and std::vector instead of Vector compiles correctly.
Check the implementation of your custom iterator.
Anyway i suggest you using the range-based syntax for this (if you use the C++ standard library):
for (auto& it : letterSets)
{
string key = it.first;
vector<char> values = it.second;
}
Related
I am trying to write a code which lists all words used in a text file without repeating. I succeeded to list all the words but I always get repeating ,the if statement line 17 always gives the value of 0.I have no idea why , the words are listed properly in the vector. Any suggestion ?
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
class reading {
public:
string word;
vector<string> words;
};
int checkifexist(string word) {
reading readingobject;
bool exist = false;
for (int i = 0; i < readingobject.words.size(); i++) {
if (word == readingobject.words[i]) {
exist = true;
break;
}
}
return exist;
}
int main() {
reading readingobject;
ifstream inFile;
inFile.open("Book.txt");
if (inFile.fail()) {
cout << "file didn't open" << endl;
exit(1);
}
readingobject.word.resize(1);
while (!inFile.eof()) {
inFile >> readingobject.word;
if (checkifexist(readingobject.word) == 1)
continue;
cout << readingobject.word << endl;
readingobject.words.push_back(readingobject.word);
}
return 0;
}
Inside of checkifexist(), you are creating a new reading object, whose words vector is empty, so there is nothing for the loop to do, and the function returns 0.
You need to instead pass in the reading object from main() as an input parameter, eg:
#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
class reading {
public:
vector<string> words;
};
bool checkifexist(const reading &readingobject, const string &word)
{
for (size_t i = 0; i < readingobject.words.size(); ++i) {
if (word == readingobject.words[i]) {
return true;
}
}
return false;
/* alternatively:
return (std::find(readingobject.words.begin(), readingobject.words.end(), word) != readingobject.words.end());
*/
}
int main()
{
reading readingobject;
string word;
ifstream inFile;
inFile.open("Book.txt");
if (!inFile) {
cout << "file didn't open" << endl;
return 1;
}
while (inFile >> word) {
if (checkifexist(readingobject, word))
continue;
cout << word << endl;
readingobject.words.push_back(word);
}
return 0;
}
Alternatively, when it comes to tracking unique elements, you can use a std::set instead of a std::vector, eg:
#include <iostream>
#include <fstream>
#include <set>
using namespace std;
class reading {
public:
set<string> words;
};
int main()
{
reading readingobject;
string word;
ifstream inFile;
inFile.open("Book.txt");
if (!inFile) {
cout << "file didn't open" << endl;
return 1;
}
while (inFile >> word) {
if (readingobject.words.insert(word).second)
cout << word << endl;
}
return 0;
}
I'm trying to write a program that first checks if a name is in a vector and if not then adds it to the vector. My code seems to have difficulties with parsing, at least that's what I get out of it. I tried changing the string to a char but it did not help me much.
#include <iostream>
#include <vector>
#include <string>
bool isinVector(std::string uElement, std::vector<std::string> uArray)
{
for (unsigned int i = 0; i <= sizeof(uArray); i++) {
if (uArray[i] == uElement) {
return true;
}
else {
return false;
}
}
}
int main()
{
bool trigger = false;
while (!trigger) {
std::vector<std::string> names;
names.push_back("Bart");
std::string newName;
getline(std::cin, newName);
if (isinVector(newName, names))
{
std::cout << "true" << std::endl;
trigger = true;
}
else
{
std::cout << "false" << std::endl;
names.push_back(newName);
for (int i = 0; i <= sizeof(names); i++) {
std::cout << names[i] << std::endl;
}
}
}
}
I made some adjustments to your code, removing your isinVector function and using a lambda inside the main function instead. In the future please provide a concise question and example.
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using std::vector;
using std::string;
using std::cout;
using std::cin;
using std::endl;
using std::find_if;
int main(){
bool trigger = false;
while (!trigger) {
vector<string> names;
names.push_back("Bart");
string newName;
getline(cin, newName);
if(find_if(names.begin(), names.end(), [newName] (const string& name){
return !name.compare(newName);
}) != names.end()){
cout << "true" << endl;
trigger = true;
}
else{
cout << "false" << endl;
names.push_back(newName);
for (size_t i = 0; i < names.size(); i++) {
cout << names.at(i) << endl;
}
}
}
return 0;
}
The code uses std::find_if to check if the element exists in the vector. If std::find_f does not return the iterator to uArray.end() Then the element exists. Also your for loop used sizeof which is incorrect, use the vector.size method. And you were looping until <= , it should be < uArray.size() And it's safer to access elements in the vector through the .at method rather than an index [] since the .at will throw an out_of_range exception.
Among the things wrong in the updated post.
Improper use of sizeof
Reinventing a standard algorithm
Lack of error checking
Consider the tasks you're trying to accomplish. You want to:
Initialize a starting vector containing the name Bart
Continuously read new names. For each new name read:
a. Check to see if it is already in the vector.
if it is present terminate the read loop
else add it to the vector, and print the entire vector
This sequence of operations can be accomplished with stepwise refinement.
Step 1. Read names
First, you need to be able to continuously read names:
#include <iostream>
#include <string>
int main()
{
std::string name;
while (std::getline(std::cin, name))
std::cout << name << '\n';
}
Simple enough. Running this will echo any strings you type, one at a time, separated by newlines.
Step 2. Accumulate names in a vector
Next, we need to add a vector to hold the strings we're reading, with an initial population of the name "Bart". For this pass we'll be just putting every string we read into the vector
#include <iostream>
#include <vector>
#include <string>
int main()
{
std::vector<std::string> names = { "Bart" };
std::string name;
while (std::getline(std::cin, name))
{
names.emplace_back(name);
for (auto const& s : names)
std::cout << s << ' ';
std::cout.put('\n');
}
}
In addition to what was done prior, we're now accumulating strings in the vector, including duplicates, and reporting the vector content after each name read. This gets us closer to our stated goal.
Step 3: Conditional loop exit based on duplicate detection
Now we need to check for duplicates, and terminate the loop once it happens. We can do this using std::find. The final code is below:
#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
int main()
{
std::vector<std::string> names = { "Bart" };
std::string name;
while (std::getline(std::cin, name))
{
if (std::find(names.begin(), names.end(), name) != names.end())
break;
names.emplace_back(name);
for (auto const& s : names)
std::cout << s << ' ';
std::cout.put('\n');
}
}
That's it. This is a simple task, but it lends itself nicely to an example of how you break a multi-part task down to manageable objectives , then build it in pieces.
Hope you found it useful.
Now my code looks like this:
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
bool isinVector (std::string uElement, std::vector<std::string> uArray) {
bool invector = false;
std::vector<std::string>::iterator it = std::find(uArray.begin(),
uArray.end(),uElement);
if(it != uArray.end()){
invector = true;
}
return invector;
}
int main(){
bool trigger = false;
std::string name;
std::vector<std::string> names = { "Bart" };
while (std::getline(std::cin, name)){
if (isinVector(name, names)) {
std::cout << "true" << std::endl;
break;
}
else
{
std::cout << "false" << std::endl;
names.emplace_back(name);
}
}
return 0;
}
and it works, thanks a lot guys!
Hello guys I'am trying to insert numbers form text file into a vector of int
the text file called "graphe.txt" its content like :
enter image description here
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <sstream>
#include <cstdlib>
using namespace std;
void load(ifstream & inputFile, vector < int > G) {
string currentLine;
if (inputFile.is_open()) //Always test the file open.
{
while (getline(inputFile, currentLine)) {
if (currentLine.length() == 0) {
break;
} else {
int s = stoi(currentLine);
G.push_back(s);
}
}
inputFile.close();
} else
cout << "file is not open" << '\n';
}
void shwTab(vector < int > G) {
vector < int > ::iterator it;
for (it = G.begin(); it != G.end(); ++it)
cout << * it << " \n";
cout << endl;
}
int main() {
ifstream inputFile("graphe.txt");
vector < int > G;
load(inputFile, G);
shwTab(G);
return 0;
}
and the output is like :
https://i.stack.imgur.com/1Wx03.png
I dont know exactly where the problem is ? the numbers doesnt appear !
Pass vector<int> G as reference, in your example a copy of G is passed to load.
void load(ifstream& inputFile,vector<int> &G)
Notice the & before G.
Not that relevant, but you could do the same for the shwTab function:
void shwTab (vector<int> &G)
to avoid copying the entire vector. It's not necessary, but you do save some memory.
The file does open and I get the message "File opened successfully". However I can't input data from the array in file "random.csv" into my inputFile object.
The data in random.csv is:
Boston,94,-15,65
Chicago,92,-21,72
Atlanta,101,10,80
Austin,107,19,81
Phoenix,112,23,88
Washington,88,-10,68
Here is my code:
#include "main.h"
int main() {
string item; //To hold file input
int i = 0;
char array[6];
ifstream inputFile;
inputFile.open ("random.csv",ios::in);
//Check for error
if (inputFile.fail()) {
cout << "There was an error opening your file" << endl;
exit(1);
} else {
cout << "File opened successfully!" << endl;
}
while (i < 6) {
inputFile >> array[i];
i++;
}
for (int y = 0; y < 6; y++) {
cout << array[y] << endl;
}
inputFile.close();
return 0;
}
Hello and welcome to Stack Overflow (SO). You can use std::getline() to read each line from the file, and then use boost::split() to split each line into words. Once you have an array of strings for each line, you can use a container of your liking to store the data.
In the example below I've used an std::map that stores strings and a vector of ints. Using a map will also sort the entrances using the key values, which means that the final container would be in alphabetical order. The implementation is very basic.
#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <fstream>
#include <boost/algorithm/string.hpp>
#include <boost/algorithm/string/split.hpp>
#include <ctype.h>
typedef std::map<std::string,std::vector<int>> ContainerType;
void extract(ContainerType &map_, const std::string &line_)
{
std::vector<std::string> data;
boost::split(data, line_, boost::is_any_of(","));
// This is not the best way - but it works for this demo.
map_[data[0]] = {std::stoi(data[1]),std::stoi(data[2]),std::stoi(data[3])};
}
int main()
{
ContainerType map;
std::ifstream inputFile;
inputFile.open("random.csv");
if(inputFile.is_open())
{
std::string line;
while( std::getline(inputFile,line))
{
if (line.empty())
continue;
else
extract(map,line);
}
inputFile.close();
}
for (auto &&i : map)
{
std::cout<< i.first << " : ";
for (auto &&j : i.second)
std::cout<< j << " ";
std::cout<<std::endl;
}
}
Hope this helps.
I'm a beginner in c++ and required to write a c++ program to read and print a csv file like this.
DateTime,value1,value2
12/07/16 13:00,3.60,50000
14/07/16 20:00,4.55,3000
May I know how can I proceed with the programming?
I manage to get the date only via a simple multimap code.
I spent some time to make almost (read notice at the end) exact solution for you.
I assume that your program is a console application that receives the original csv-file name as a command line argument.
So see the following code and make required changes if you like:
#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <map>
#include <string>
std::vector<std::string> getLineFromCSV(std::istream& str, std::map<int, int>& widthMap)
{
std::vector<std::string> result;
std::string line;
std::getline(str, line);
std::stringstream lineStream(line);
std::string cell;
int cellCnt = 0;
while (std::getline(lineStream, cell, ','))
{
result.push_back(cell);
int width = cell.length();
if (width > widthMap[cellCnt])
widthMap[cellCnt] = width;
cellCnt++;
}
return result;
}
int main(int argc, char * argv[])
{
std::vector<std::vector<std::string>> result; // table with data
std::map<int, int> columnWidths; // map to store maximum length (value) of a string in the column (key)
std::ifstream inpfile;
// check file name in the argv[1]
if (argc > 1)
{
inpfile.open(argv[1]);
if (!inpfile.is_open())
{
std::cout << "File " << argv[1] << " cannot be read!" << std::endl;
return 1;
}
}
else
{
std::cout << "Run progran as: " << argv[0] << " input_file.csv" << std::endl;
return 2;
}
// read from file stream line by line
while (inpfile.good())
{
result.push_back(getLineFromCSV(inpfile, columnWidths));
}
// close the file
inpfile.close();
// output the results
std::cout << "Content of the file:" << std::endl;
for (std::vector<std::vector<std::string>>::iterator i = result.begin(); i != result.end(); i++)
{
int rawLen = i->size();
for (int j = 0; j < rawLen; j++)
{
std::cout.width(columnWidths[j]);
std::cout << (*i)[j] << " | ";
}
std::cout << std::endl;
}
return 0;
}
NOTE: Your task is just to replace a vector of vectors (type std::vector<std::vector<std::string>> that are used for result) to a multimap (I hope you understand what should be a key in your solution)
Of course, there are lots of possible solutions for that task (if you open this question and look through the answers you will understand this).
First of all, I propose to consider the following example and to try make your task in the simplest way:
#include <iostream>
#include <sstream>
#include <vector>
#include <string>
using namespace std;
int main()
{
string str = "12/07/16 13:00,3.60,50000";
stringstream ss(str);
vector<string> singleRow;
char ch;
string s = "";
while (ss >> ch)
{
s += ch;
if (ss.peek() == ',' || ss.peek() == EOF )
{
ss.ignore();
singleRow.push_back(s);
s.clear();
}
}
for (vector<string>::iterator i = singleRow.begin(); i != singleRow.end(); i++)
cout << *i << endl;
return 0;
}
I think it can be useful for you.