I'm trying to find what is the difference between the static and the dynamic allocation of the table in this code, I'm interested most about the initial state or values n that table.
when I tried the code with the static allocation the program didn't work and i can see that the table contain random value but with the dynamic allocation it works better.
can someone explain to me how this work thanks.
#include <string>
#include <stdio.h>
#include <iostream>
using namespace std ;
bool isUnique(std::string s)
{
if(s.length()> 128 ) return false;
//bool lettre[128];
bool* lettre = new bool[128];
for (int i = 0; i < s.length(); i++)
{
int index = s[i];
if (lettre[index] == true)
return false;
lettre[index] = true;
}
for(int i=0; i<128;i++)
{
cout<< lettre[i] +" |";
}
cout<<endl;
return true;
}
int main()
{
std::string s1 = "adcadef";
std::string s2 = "abcdef";
cout<< isUnique(s1) << endl;
cout << isUnique(s2) << endl;
return 0;
}
Related
I working on a program that simulates travel agents booking flights in parallel. It spins up a process for each agent and works against an array of Plane objects held in shared memory.
I'm getting a segmentation fault when I try to push a row of seats back to the plane. The method to parse the input file calls a SetSeats() method on Plane objects. Each Plane contains a vector<map<char, Seat>> (each index of the vector is a row, each key of each map is the letter of a seat on that row). When I call SetSeats() it goes fine through adding seats to the first map, i.e. the first row of seats. It throws the segfault when I try to push the map back to the seats vector.
I saw something online about pushing back custom classes to vectors needing deconstructors, so I added them to Seat.h and Plane.h.
Code for the main program:
#include <iostream>
#include <map>
#include <vector>
#incluce <string>
#include <fstream>
#include "Seat.h"
#include "Plane.h"
void ParseInputFile(ifstream &inFS, int numPlanes, int &numAgents);
int shmid;
int *timer;
int numPlanes, numAgents;
struct sembuf *ops;
Plane *sharedPlanes;
map<string, Plane*> planes;
using namespace std;
int main(int argc, char *argv[])
{
ifstream inFS;
// code to get an input file from command line arguments and get number of planes from it
// set up shared memory segment
long key = XXX; // just a long integer
int nbytes = 1024;
shmid = shmget((key_t)key, nbytes, 0666 | IPC_CREAT);
if (shmid == -1)
{
printf("Error in shared memory region setup.\n");
perror("REASON");
exit(2);
}
// initialize global variables
sharedPlanes = new Plane[numPlanes];
timer = new int;
ops = new sembuf[1];
// attached shared pointers to shared memory segment
sharedPlanes = (Plane*)shmat(shmid, (Plane*)0, 0);
timer = (int*)shmat(shmid, (int*)0, 0);
*timer = 0;
inFS.open(inputFile);
ParseInputFile(inFS, numPlanes, numAgents); // breaks in here
// the rest of main()
}
void ParseInputFile(ifstream &inFS, int numPlanes, int &numAgents)
{
string line = "";
bool foundNumberOfPlanes = false;
bool foundPlanes = false;
bool foundNumberOfAgents = false;
bool lookingForAgent = false;
bool foundAgent = false;
int planeNo = 0;
int agentNo = 0;
int opNo = 0;
map<string, Operation> ops;
vector<Request> agentRequests;
while (getline(inFS, line))
{
if (!CommonMethods::IsWhitespace(line))
{
// code to read first line
if (foundNumberOfPlanes && !foundPlanes)
{
// parse a line from the input file to get details about the plane
Plane *plane = &sharedPlanes[planeNo];
unsigned int rows = xxx; // set based on the plane details
unsigned int seatsPerRow = xxx; set based on the plane details
plane->SetSeats(rows, seatsPerRow); // this is the method where I get the seg fault
// finish defining the plane
continue;
// the rest of the method
}
}
}
}
Code for Plane.h:
#pragma once
#include <iostream>
#include <string>
#include <map>
#include <tuple>
#include <vector>
#include "Seat.h"
#include "Exceptions.h"
#include "ReservationStatus.h"
#include "CommonMethods.h"
using namespace std;
class Plane
{
private:
vector<map<char, Seat>> seats;
unsigned int numberOfRows, numberOfSeatsPerRow;
public:
Plane(unsigned int numberOfRows, unsigned int numberOfSeatsPerRow);
Plane() {}
void SetSeats(unsigned int numberOfRows, unsigned int numberOfSeatsPerRow);
};
void Plane::SetSeats(unsigned int numberOfRows, unsigned int numberOfSeatsPerRow)
{
//cout << "Clearing old seats" << endl;
if (!seats.empty())
{
//cout << "Seats not empty" << endl;
for (int i = 0; i < (int)seats.size(); i++)
{
//cout << "checking row " << i << endl;
if (!seats.at(i).empty())
{
//cout << "Row " << i << " not empty" << endl;
seats.at(i).clear();
}
}
}
cout << "Rows: " << numberOfRows << ", Seats: " << numberOfSeatsPerRow << endl;
this->numberOfRows = numberOfRows;
this->numberOfSeatsPerRow = numberOfSeatsPerRow;
for (unsigned int i = 0; i < this->numberOfRows; i++)
{
map<char, Seat> row;
for (unsigned int j = 0; j < this->numberOfSeatsPerRow; j++)
{
Seat seat;
seat.RowNumber = i + 1;
seat.SeatLetter = j + 'A';
//cout << "Inserting seat " << seat.RowNumber << seat.SeatLetter << endl;
row.insert(pair<char, Seat>(seat.SeatLetter, seat));
}
if (!row.empty())
{
cout << "inserting row " << (i + 1) << endl;
seats.push_back(row);
}
}
}
void Plane::ProcessWaitAny(int t)
{
while (!WaitingList.empty())
{
bool booked = false;
string pass = WaitingList.front();
WaitingList.pop();
for (unsigned int j = 0; j < numberOfRows; j++)
{
if (booked)
break;
for (unsigned int k = 0; k < numberOfSeatsPerRow; k++)
{
Seat *s = &seats.at(j)[k + 'A'];
if (!s->IsBooked)
{
Reserve(s, pass);
booked = true;
string seatNo = to_string(j);
seatNo += (k + 'A');
cout << "Passenger " << pass << " booked into seat " << seatNo << " at time " << t << endl;
break;
}
}
}
if (!booked)
return;
}
}
Code for Seat.h
#pragma once
#include <iostream>
#include <string>
#include <queue>
using namespace std;
struct Seat
{
string Passenger = "";
bool IsBooked = false;
unsigned int RowNumber;
char SeatLetter;
queue<string> WaitingList;
};
I have made a minimum working example of your problem:
#include <vector>
#include <sys/shm.h>
#include <iostream>
class Bar {
public:
Bar() {};
std::vector<int> vec;
};
int main() {
int shmid;
Bar* a = new Bar();
a->vec.push_back(1);
// set up shared memory segment
long key = 0x123455; // just a long integer
int nbytes = 1024;
shmid = shmget((key_t)key, nbytes, 0666 | IPC_CREAT);
if (shmid == -1)
{
printf("Error in shared memory region setup.\n");
perror("REASON");
exit(2);
}
a = (Bar*)shmat(shmid, (Bar*)0, 0);
a->vec.push_back(2);
}
The problem is your wrong usage of shmat. The pointer sharedPlane just points to some unitialized shared memory. You have to make sure that the address provided by key is 'right'. To do this, do the following:
Your other process, call Plane * other_process_sharedPlane = new Plane();. Remove the line sharedPlanes = new Plane[numPlanes]; from your main programm.
In your main process, set key to the value of other_process_sharedPlane
Then you can call shmget and shmadd
I am writing a method in C++ which will take a string of 2 or more words and output each individual word of the string separated by a second or so, using the sleep() method. I am trying to do this using a for loop and substrings. I am unsure also of the regexs which should be used, and how they should be used, to achieve the desired output.
I have reviewed this and this and find my question differs since I am trying to do this in a loop, and not store the individual substrings.
Input:
"This is an example"
Desired output:
"This " (pause) "is " (pause) "an " (pause) "example."
Use std::stringstream, no regular expressions required:
#include <iostream>
#include <sstream>
using namespace std;
int main() {
stringstream ss("This is a test");
string s;
while (ss >> s) {
cout << s << endl;
}
return 0;
}
Also, see How do I tokenize a string in C++?
Here are a pair of implementations that don't involve creating any extraneous buffers.
#include <boost/range/adaptor/filtered.hpp>
#include <boost/range/algorithm/copy.hpp> //for boost::copy
#include <chrono>
#include <iostream>
#include <string>
#include <experimental/string_view> //in clang or gcc; or use boost::string_ref in boost 1.53 or later; or use boost::iterator_range<char*> in earlier version of boost
#include <thread>
void method_one(std::experimental::string_view sv)
{
for(auto b = sv.begin(), e = sv.end(), space = std::find(b, e, ' ')
; b < e
; b = space + 1, space = std::find(space + 1, e, ' '))
{
std::copy(b, space, std::ostreambuf_iterator<char>(std::cout));
std::cout << " (pause) "; //note that this will spit out an extra pause the last time through
std::this_thread::sleep_for(std::chrono::seconds(1));
}
}
void method_two(std::experimental::string_view sv)
{
boost::copy(
sv | boost::adaptors::filtered([](const char c) -> bool
{
if(c == ' ')
{
std::cout << " (pause) "; //note that this spits out exactly one pause per space character
std::this_thread::sleep_for(std::chrono::seconds(1));
return false;
}
return true;
})
, std::ostreambuf_iterator<char>(std::cout)
);
}
int main() {
const std::string s{"This is a string"};
method_one(s);
std::cout << std::endl;
method_two(s);
std::cout << std::endl;
return 0;
}
Live on coliru, if you're into that.
you can implement your own method:
//StrParse.h
#pragma once
#include <iostream>
static counter = 0;
char* strPar(char* pTxt, char c)
{
int lenAll = strlen(pTxt);
bool strBeg = false;
int nWords = 0;
for(int i(0); i < lenAll; i++)
{
while(pTxt[i] != c)
{
strBeg = true;
i++;
}
if(strBeg)
{
nWords++;
strBeg = false;
}
}
int* pLens = new int[nWords];
int j = 0;
int len = 0;
for(i = 0; i < lenAll; i++)
{
while(pTxt[i] != c)
{
strBeg = true;
i++;
len++;
}
if(strBeg)
{
pLens[j] = len;
j++;
strBeg = false;
len = 0;
}
}
char** pStr = new char*[nWords + 1];
for(i = 0; i < nWords; i++)
pStr[i] = new char[pLens[i] + 1];
int k = 0, l = 0;
for(i = 0; i < lenAll; i++)
{
while(pTxt[i] != c)
{
strBeg = true;
pStr[k][l] = pTxt[i];
l++;
i++;
}
if(strBeg)
{
pStr[k][l] = '\0';
k++;
l = 0;
strBeg = false;
}
}
counter++;
if(counter <= nWords)
return pStr[counter - 1];
else
return NULL;
}
//main.cpp
#include "StrParse.h"
void main()
{
char* pTxt = " -CPlusPlus -programming -is -a - superb thing ";
char* pStr1 = NULL;
int i = 1;
char sep;
std::cout << "Separator: ";
sep = std::cin.get();
std::cin.sync();
while(pStr1 = strPar(pTxt, sep))
{
std::cout << "String " << i << ": " << pStr1 << std::endl;
delete pStr1;
i++;
}
std::cout << std::endl;
}
I have been attempting to find a way to sort an array of pointers (pointing to strings) and then display the non-sorted list and the sorted list but no mater what I try the 2nd printed list is always identical to the original non-sorted list. Any help you could offer would be greatly appreciated (and I'm sorry if my code is a mess I'm a new student)
this is my main(lab5.cpp)
#include <cstdlib>
#include <iostream>
#include "student.h"
#include <string>
using namespace std;
int main(int argc, char *argv[])
{
student stu;
stu.list();
system("PAUSE");
return EXIT_SUCCESS;
}
This is my header(student.h)
#include <string>
class student
{
public:
student( );
void setnameage();
int getage(int);
std::string getname(int);
void sort();
void list();
private:
std::string name[50];
std::string nameL[50];
int age[50];
std::string * Pname ;
int * Page;
int amount;
};
This is my object (student.cpp)
#include <iostream>
#include <iomanip>
#include "student.h"
#include <string>
using namespace std;
//constructor
student::student()
{
int i = 0;
amount = 0;
Pname = name;
Page = age;
while (i != 50)
{
age[i] = 0;
name[i] = "A";
i = i +1 ;
}
std::cout << "Enter number of students(max 50) \n" << ">";
std::cin >> amount;
}
//sets the neame and the age
void student::setnameage()
{
int i = 0;
while (i != amount)
{
std::cout << "Enter name " << i+1 <<" (last, first):";
std::cin >> name[i] >> nameL[i];
std::cout << "enter age";
std::cin >> age[i];
i++;
}
}
//get age
int student::getage(int i)
{
return age[i];
}
//get name
std::string student::getname(int i)
{
return name[i];
}
//sorts the aray of pointers
void student::sort()
{
std::string tempL;
int tempN;
i = 0
for (int i = 1; i <= amount-1; i++)
{
for(int j=i+1; j <= amount; j++)
{
if(Pname[i].compare(Pname[j]) > 0)
{
tempN = Page[i];
Page[i] = Page[j];
Page[j] = tempN;
// tempL = Pname[i];
Pname[i].swap(Pname[j]);
//Pname[j] = tempL;
}
}
}
}
//displayes the final results
void student::list()
{
setnameage();
int i = 0;
std::cout << "original list\n-------------";
while(i != amount)
{
std::cout<< "\n" << getname(i) << ">" << getage(i);
i++;
}
sort();
i = 0;
std::cout << "\nAlphabetized list\n-------------";
while(i != amount)
{
std::cout<< "\n" << Pname[i] << ">" << Page[i];
i++;
}
}
First let me say your program has a lot of design problems, but to answer your actual question:
The trouble is you don't have an array of 50 pointers, you just have one pointer to the start of the array. In your sort function you have this line to swap the string pointers:
Pname[i].swap(Pname[j]);
But this doesn't swap the pointers, it swaps the original strings. So instead of ending up with the original array of strings, and a re-ordered array pointing to those strings, you just end up with an array of re-ordered strings.
You should change std::string* pName; to std::string* pName[50];. At the start of your program, initialise the array to point to the strings.
for (int i = 0; i < 50; i++) pName[i] = &name[i];
Then in your sort function you should use std::swap() to swap the pointers themselves:
std::swap(pName[i], pName[j]);
Finally, since pName[i] is now a pointer, whenever you actually want to access the string you have to dereference the pointer. For example,
if(Pname[i].compare(Pname[j]) > 0)
becomes
if(Pname[i]->compare(*Pname[j]) > 0)
The same problem exists with your method of sorting the ages.
A much better design for your program would be to use std::list<std::pair<std::string, int>> to store the names and ages. Then you can use the built in sorting functions to sort the list (and easily make a copy of it if you need to keep the original as well).
I have been trying to use this c++ program to sort 5 names alphabetically:
#include <iostream>
#include <cstring>
#include <conio.h>
using namespace std;
int main()
{
char names[5][100];
int x,y,z;
char exchange[100];
cout << "Enter five names...\n";
for(x=1;x<=5;x++)
{
cout << x << ". ";
cin >> names[x-1];
}
getch();
for(x=0;x<=5-2;x++)
{
for(y=0;y<=5-2;y++)
{
for(z=0;z<=99;z++)
{
if(int(names[y][z])>int(names[y+1][z]))
{
strcpy(exchange,names[y]);
strcpy(names[y],names[y+1]);
strcpy(names[y+1],exchange);
break;
}
}
}
}
for(x=0;x<=5-1;x++)
cout << names[x];
return 0;
}
If I enter Earl, Don, Chris, Bill, and Andy respectively, I get this:
AndyEarlDonChrisBill
Could someone please tell me whats wrong with my program?
You could use std::set or std::multiset (if you will allow repeated items) of strings, and it will keep the items sorted automatically (you could even change the sorting criteria if you want).
#include <iostream>
#include <set>
#include <algorithm>
void print(const std::string& item)
{
std::cout << item << std::endl;
}
int main()
{
std::set<std::string> sortedItems;
for(int i = 1; i <= 5; ++i)
{
std::string name;
std::cout << i << ". ";
std::cin >> name;
sortedItems.insert(name);
}
std::for_each(sortedItems.begin(), sortedItems.end(), &print);
return 0;
}
input:
Gerardo
Carlos
Kamilo
Angel
Bosco
output:
Angel
Bosco
Carlos
Gerardo
Kamilo
You can use the sort function:
#include <algorithm>
#include <vector>
using namespace std;
...
vector<string> s;
sort(s.begin(),s.end());
You are using too much unnecessary loops. Try this simple and efficient one. You need to just swap when a string is alphabetically latter than other string.
Input
5
Ashadullah
Shawon
Shakib
Aaaakash
Ideone
Output
Aaaakash
Ashadullah
Ideone
Shakib
Shawon
#include <bits/stdc++.h>
using namespace std;
int main()
{
string s[200],x[200],ct,dt;
int i,j,n;
cin>>n;
for(i=0;i<n;i++)
{
cin>>s[i];
}
for(i=0;i<n;i++)
{
for(j=i+1;j<n;j++)
{
if(s[i]>s[j])
{
ct=s[i];
s[i]=s[j];
s[j]=ct;
}
}
}
cout<<"Sorted Name in Dictionary Order"<<endl;
for(i=0;i<n;i++)
{
cout<<s[i]<<endl;
}
return 0;
}
Your code implements a single-pass of bubble sort. Essentially missing the 'repeat until no changes are made to the array' loop around the outside.
The code does not take care when the names are already in order. Add the following
else if(int(names[y][z])<int(names[y+1][z]))
break;
To the if statement.
Putting this here in case someone needs a different solution.
/* sorting example */
#include <iostream>
using namespace std;
bool isSwap( string str1, string str2, int i)
{
if(str1[i] > str2[i])
return true;
if(str1[i] == str2[i])
return isSwap(str1,str2,i+1);
return false;
}
int main()
{
string str[7] = {"you","your","must","mike", "jack", "jesus","god"};
int strlen = 7;
string temp;
int i = 0;
int j = 0;
bool changed = false;
while(i < strlen-1)
{
changed = false;
j = i+1;
while(j < strlen)
{
if(isSwap(str[i],str[j],0))
{
temp = str[i];
str[i] = str[j];
str[j] = temp;
changed = true;
}
j++;
}
if(changed)
i = 0;
else
i++;
}
for(i = 0; i < strlen; i++)
cout << str[i] << endl;
return 0;
}
It's crashing at the very end of the main() function where it needs to delete the starters objects. The error message that pops up when I run the program says: Debug assertion failed! Expression: _BLOCK_IS_VALID(pHead->nBlockUse). How do i fix it from crashing when deleting the starters objects?
#include <iostream>
#include <fstream>
#include "olympic.h"
using namespace std;
ofstream csis;
int main() {
const int lanes = 4;
Ranker rank(lanes);
csis.open("csis.txt");
// First make a list of names and lane assignments.
Competitor* starters[lanes];
starters[0] = new Competitor("EmmyLou Harris", 1);
starters[1] = new Competitor("Nanci Griffith", 2);
starters[2] = new Competitor("Bonnie Raitt", 3);
starters[3] = new Competitor("Joni Mitchell", 4);
// The race is run; now assign a time to each person.
starters[0]->setTime((float)12.0);
starters[1]->setTime((float)12.8);
starters[2]->setTime((float)11.0);
starters[3]->setTime((float)10.3);
// Put everyone into the ranker.
for (int i = 0; i < lanes; i++)
rank.addList(starters[i]);
// Now print out the list to make sure its right.
cout << "Competitors by lane are:" << endl;
csis << "Competitors by lane are:" << endl;
for (int i = 1; i <= lanes; i++)
rank.getLane(i)->print();
// Finally, show how they finished.
cout << "Rankings by finish are:" << endl;
csis << "Rankings by finish are:" << endl;
for (int i = 1; i <= lanes; i++)
rank.getFinish(i)->print();
for (int i = 0; i < lanes; i++)
delete starters[i];
csis.close();
}
ranker.cpp:
#include "ranker.h"
#include "competitor.h"
#include <stdlib.h>
Ranker::Ranker(int lanes) {
athlete = new Competitor*[lanes];
numAthletes = 0;
maxAthletes = lanes;
}
int Ranker::addList(Competitor* starter) {
if (numAthletes < maxAthletes && starter != NULL) {
athlete[numAthletes] = starter;
numAthletes++;
return numAthletes;
}
else
return 0;
}
Competitor* Ranker::getLane(int lane) {
for (int i = 0; i < numAthletes; i++) {
if (athlete[i]->getLane() == lane) {
return athlete[i];
}
}
return NULL;
}
Competitor* Ranker::getFinish(int position) {
switch(position) {
case 1:
return athlete[3];
break;
case 2:
return athlete[2];
break;
case 3:
return athlete[1];
break;
case 4:
return athlete[0];
break;
}
return NULL;
}
int Ranker::getFilled() {
return numAthletes;
}
Ranker::~Ranker() {
delete [] athlete;
}
competitor.h:
#ifndef _COMPETITOR_H
#define _COMPETITOR_H
class Competitor {
private:
char* name;
int lane;
double time;
public:
Competitor(char* inputName, int inputLane);
Competitor();
void setTime(double inputTime);
char* getName();
int Competitor::getLane();
double getTime();
void print();
~Competitor();
};
#endif
competitor.cpp:
#include "competitor.h"
#include <string>
#include <iostream>
#include <iomanip>
using namespace std;
Competitor::Competitor(char* inputName, int inputLane) {
name = inputName;
lane = inputLane;
}
Competitor::Competitor() {
name = 0;
lane = 0;
time = 0;
}
void Competitor::setTime(double inputTime) {
time = inputTime;
}
char* Competitor::getName() {
return name;
}
int Competitor::getLane() {
return lane;
}
double Competitor::getTime() {
return time;
}
void Competitor::print() {
cout << setw(20) << name << setw(20) << lane << setw(20) << setprecision(4) << time << endl;
}
Competitor::~Competitor() {
delete [] name;
}
Call stack:
before crash: http://i.imgur.com/d4sKbKV.png
after crash: http://i.imgur.com/C5cXth9.png
After you've added Competitor class, it seems the problem is that you delete its name in Competitor's destructor. But you assign it from string literal which can't really be deleted. I'm sure the stack trace leading to assertion will prove that.
One way of solving the problem would be using std::string to store the name.
Problem is when deleting the char* value on destructor, which is assigned with const char instead new char. So i have slightly changed the constructor to copy the const char to new char.
Competitor::Competitor(char* inputName, int charlen, int inputLane)
{
name = new char[charlen + 1];
memcpy(name , inputName, charlen );
name [charlen] = '\0';
lane = inputLane;
}