I'm making a program that converts bytes from a string into a binary system and then store them into a vector. I need to use bitset to convert them. My question is: how can i store the results in a vector b? I thought about saving them one number by one number, but how the loop would look like?
string key = "codekeys";
char text;
vector<int> k;
vector<int> b;
void f() {
for(char& text : key) {
k.push_back(text);
}
cout << "k size: " << k.size() << endl;
for(int i=0; i<k.size(); i++) {
cout << k[i] << " in binary " << bitset<8> (k[i]) << endl;
}
}
If you make b a vector of bitsets then you can store them easily.
string key = "codekeys";
char text;
vector<int> k;
vector<bitset<8>> b;
void f() {
for(char& text : key) {
k.push_back(text);
b.push_back(bitset<8>(text)); // convert to bitset and store in b
}
cout << "k size: " << k.size() << endl;
for(int i=0; i<k.size(); i++) {
cout << k[i] << " in binary " << b[i] << endl; // print b
}
}
Related
So, I have a vector of boats. I need to access these boats and modify them (i.e. delete them) regularly, so it would be really nice if I could print their index along with all their other information, but I can't seem to figure out how.
The closest I got to it was with a simple for loop, but that eventually prints the current index along with the previous ones, as the vector size grows (since my i was < vector.size())
vector <Boat> berths_reg;
//print vector elements info
void Boat::print_info()
{
cout << endl;
for(int i = 0; i < berths_reg.size(); i++)
{
cout << "Index : " << i << endl;
}
cout << "Boat type : " << type << endl;
cout << "Boat length : " << length << endl;
cout << "Draft depth : " << draft << endl;
cout << endl;
}
//iterate through vector to print all elements
void print_vector()
{
vector <Boat> ::iterator it;
for (it = berths_reg.begin(); it != berths_reg.end(); ++it)
{
it->print_info();
}
}
//Storing boats (objects data) inside vector
void add_boat(Boat* b, string type, int length, int draft)
{
b->get_type(type);
b->get_length(length);
b->get_draft(draft);
berths_reg.push_back(*b);
}
Simply print both the index and the info within the same loop:
void print_vector()
{
for(int i = 0; i < berths_reg.size(); ++i)
{
cout << "Index : " << i << endl;
berths_reg[i].print_info();
}
}
In the following code, when run using GNU GCC v8.2.0, code does not terminate:
int main(void)
{
/* code */
int myArray[] = {2, 4};
int otherArray[] = {777, 888};
for(int i = 0; i<4; i++)
{
myArray[i] = 0;
cout << "myArray[" << i << "]=";
cout << myArray[i] << endl;
cout << "add: " << &myArray[i] << endl;
}
for(int i = 0; i<2; i++)
{
cout << "otherArray[" << i << "]=";
cout << otherArray[i] << endl;
cout << "add: " << &otherArray[i] << endl;
}
return 0;
}
output:
add:0x28ff24
myarray[2]=0
add:0x28ff28
myarray[0]=0
add:0x28ff20
myarray[1]=0
add:0x28ff24
myarray[2]=0
add:0x28ff28
myarray[0]=0
add:0x28ff20
myarray[1]=0
add:0x28ff24
myarray[2]=0
add:0x28ff28
myarray[0]=0
add:0x28ff20
myarray[1]=0
add:0x28ff24
myarray[2]=0
add:0x28ff28
myarray[0]=0
add:0x28ff20
myarray[1]^C
for(int i = 0; i<4; i++)
Replace the 4 in the 'for loop' by 2 like this:
for(int i = 0; i<2; i++)
Since you're using a static array so it's better to specify the fixed size, but the most important is to be aware when you try to access the array by comparing the index being processed with the size of the array to avoid this behavior.
You are invoking undefined behaviour by writing the indexes 0-3 of the 2 element array myArray.
As this is undefined behaviour there are no guarantees as to what is happening or what will happen if you run the code again in the future. A likely explanation for your observed behaviour is that when you write myArray[2] that is actually overwriting the value of i causing your loop to restart back at 0.
The simple solution is to make myArray larger or change your for loop limit to 2.
To detect this sort of behaviour use std::array instead and call the at function which has bounds checking and will throw an exception when you go outside the bounds of the array. e.g.:
#include <array>
#include <iostream>
int main(void)
{
/* code */
std::array< int, 2 > myArray = { 2, 4 };
std::array< int, 2 > otherArray = { 777, 888 };
for(int i = 0; i<4; i++)
{
myArray.at(i) = 0;
std::cout << "myArray[" << i << "]=";
std::cout << myArray[i] << "\n";
std::cout << "add: " << &myArray.at(i) << "\n";
}
for(int i = 0; i<2; i++)
{
std::cout << "otherArray[" << i << "]=";
std::cout << otherArray.at(i) << "\n";
std::cout << "add: " << &otherArray.at(i) << "\n";
}
return 0;
}
std::array also has the bonus of a size() method which can make your code safer too:
for(int i = 0; i<myArray.size(); i++)
{
myArray.at(i) = 0;
std::cout << "myArray[" << i << "]=";
std::cout << myArray[i] << "\n";
std::cout << "add: " << &myArray.at(i) << "\n";
}
I want to increase the size of the array of string after declaring it once, how can it be done. I need to increase the size in the following code..
#include<iostream>
using namespace std;
#include<string>
int main()
{
int n;
string A[] =
{ "vaibhav", "vinayak", "alok", "aman" };
int a = sizeof(A) / sizeof(A[0]);
cout << "The size is " << a << endl;
for (int i = 0; i < a; i++)
{
cout << A[i] << endl;
}
cout << "Enter the number of elements you want to add to the string"
<< endl;
cin >> n;
cout << "ok now enter the strings" << endl;
for (int i = a; i < n + a; i++)
{
cin >> A[i];
}
a = a + n;
A.resize(a); // THIS KIND OF THING
for (int i = 0; i < a; i++)
{
cout << A[i] << endl;
}
return 0;
}
Plain and simple: you cannot.
You can get a larger array, copy all your stuff over and use that instead. But why do all that, when there is a perfectly good class already there, doing it all for you: std::vector.
#include <iostream>
#include <string>
#include <vector>
int main()
{
std::vector<std::string> A = {"vaibhav", "vinayak", "alok", "aman"};
std::cout << "The size is " << A.size() << std::endl;
for(string s : A)
{
std::cout << s << std::endl;
}
// want to enter more?
sd::string more;
std::cin >> more;
A.push_back(more);
std::cout << "The size is " << A.size() << std::endl;
for(string s : A)
{
std::cout << s << std::endl;
}
return 0;
}
Convert your code over to use std::vector and this problem becomes much easier to solve.
#include<iostream>
#include<string>
#include<vector>
int main(){
int n;
std::vector<std::string> A = {"vaibhav", "vinayak", "alok", "aman"};
int a = A.size();
std::cout << "The size is " << a << std::endl;
//Prefer Range-For when just iterating over all elements
for(std::string const& str : A){
std::cout << str << std::endl;
}
std::cout << "Enter the number of elements you want to add to the string" << std::endl;
std::cin >> n;
std::cout << "ok now enter the strings" << std::endl;
for(int i = 0; i < n; i++ ) {
//emplace_back automatically resizes the container when called.
A.emplace_back();
std::cin >> A.back();
//If you're using C++17, you can replace those two lines with just this:
//std::cin >> A.emplace_back();
}
for(std::string const& str : A){
std::cout << str << std::endl;
}
return 0;
}
Also, don't use using namespace std;, since it leads to expensive to fix bugs and makes your code harder to read for other C++ programmers.
I want to increase the size of the array of string after declaring it
once, how can it be done.
It cannot be done. Use std::vector if the element count isn't known at compile time or can change dynamically. It even has a resize member function named exactly like the one in your code.
You cannot increase the size of a Raw Array, you could use an std::vecto<std::string> as this type of array can grow at runtime.
However, you could also create a class that will store an array of string and create your own implementation to resize the raw array. Which would be creating a bigger array and copying all the other values over, then setting the class array to the new array (or just return it)
I use pointers to print the contents of a string array for this program, I have trouble in printing out the item's names. Whatever I enter how many items, it prints out only one item. For example, when I entered pencil, pen, book, it only printed out the last item 3 times: book book book instead of printing: pencil pen book.
void getPrint(string *names, int num){
cout <<"Here is the items you entered: ";
for (int i=0; i<num; i++){
cout <<*names<<" ";
}
Maybe you want to treat the pointer to a single string as an array:
void getPrint(string * names, int num)
{
for (int i = 0; i < num; ++i)
{
cout << names[i] << " ";
}
cout << endl;
}
There are other possibilities:
cout << names++ << " ";
cout << *(names + i) << " ";
Look up pointer dereferencing in your favorite reference.
The preferred solution is to use std::vector<string> or std::array<string>.
void getPrint(const std::vector<std::string>& names)
{
const unsigned int quantity = names.size();
for (unsigned int i = 0; i < quantity; ++i)
{
std::cout << names[i] << " ";
}
std::cout << endl;
}
There are two possibilies:
Array syntax
Your treat your std::string as an array and increment over its indices. To be consistent you can pass the argument in array syntax as well.
void getPrint(const std::string names[], const int num){
std::cout <<"Here is the items you entered: " << std::endl;
for (int i=0; i<num; i++){
std::cout <<names[i]<<" " << std::endl;
}
}
Pointer syntax
You pass your std::string as a pointer (on the first element of you array). To reach all your elements you have to increment the pointer itself.
void getPrint(const std::string* names, const int num){
std::cout <<"Here is the items you entered: " << std::endl;
for (int i=0; i<num; i++){
std::cout <<*(names++)<<" " << std::endl; // increment pointer
}
}
Since incrementing your pointer does not need the index i anymore you can shorten the whole thing a bit (but may not declare const num anymore).
void getPrint(const std::string* names, int num){
std::cout <<"Here is the items you entered: " << std::endl;
while(num--){
std::cout <<*(names++)<<" " << std::endl;
}
}
Hope I could help you.
Edit
As mentioned above any solution using the STL containers std::vector or std::array and passing them by reference are preferred. Since they provide .begin() and .end() methods one can use (C++11)
void getPrint(const std::vector<std::string>& names){
std::cout <<"Here is the items you entered: " << std::endl;
for (auto name: names){
std::cout << name << " " << std::endl;
}
}
I am new in C++, I created a struct called Device with two fields
string MacAdress
vector<string> RSSI
Then, I created a vector of structure: vector<Device> Devices
I want to extract the vector<string> RSSI and display its contant.
Here is where I got stuck in my main.cpp:
cout << "display MAC and RSSI"<< endl;
Device CurrentDevice;
for(int j=0; j<Devices.size();j++)
{
CurrentDevice = Devices.at(j);
vector<string>::const_iterator begin = CurrentDevice.GetRSSIs().begin();
vector<string>::const_iterator last = CurrentDevice.GetRSSIs().begin() + CurrentDevice.GetRSSIs().size();
vector<string> intermed(begin+1, last);
cout << "Size: "<< intermed.size() << endl;
for (int i = 0 ; i < intermed.size(); i++)
{
cout << intermed[i] << endl;
cout << "device n°"<< j+1<<" " << "MAC "<< " "<< CurrentDevice.GetMacAdress()<< endl;
for(int k=0; k<intermed.size();k++)
{
cout << "device n°" << j;
cout << "\tRSSI " << k << " = " << intermed.at(k)<< endl;
}
}
return 0;
}
I end up with Size=0
here is some simplified code that does not use iterators but should still do the job:
#include <iostream>
#include <string>
#include <vector>
int main()
{
struct Device {
std::string MacAddress;
std::vector<std::string> RSSI;
};
std::vector<Device> Devices;
// add some stuff to first object
Device CurrentDevice1;
CurrentDevice1.MacAddress = "A-B-C";
CurrentDevice1.RSSI.push_back("rssi11");
CurrentDevice1.RSSI.push_back("rssi12");
CurrentDevice1.RSSI.push_back("rssi13");
Devices.push_back(CurrentDevice1);
// add some stuff to second object
Device CurrentDevice2;
CurrentDevice2.MacAddress = "D-E-F";
CurrentDevice2.RSSI.push_back("rssi21");
CurrentDevice2.RSSI.push_back("rssi22");
Devices.push_back(CurrentDevice2);
// see object MAC's
for (int i = 0; i < Devices.size(); i++){
std::cout << "device " << i+1 << " MAC: " << Devices[i].MacAddress << std::endl;
}
// see object RSSI's
for (int j = 0; j < Devices.size(); j++){
for (int k = 0; k < Devices[j].RSSI.size(); k++){
std::cout << "device " << j + 1 << " RSSI: " << k +1 << " : " << Devices[j].RSSI[k] << std::endl;
}
std::cout << "\n";
}
return 0;
}
I'm not sure about what do you want to obtain, but I suppose the problem is in the following lines
vector<string>::const_iterator last = CurrentDevice.GetRSSIs().begin() + CurrentDevice.GetRSSIs().size();
vector<string> intermed(begin+1, last);
Do you want to obtain a copy of CurrentDevice.GetRSSIs()?
In this case, you can use begin() and end()
vector<string> intermed(CurrentDevice().GetRSSIs().begin(),
CurrentDevice().GetRSSIs().end());
or, simpler, invoke the copy constructor,
vector<string> intermed(CurrentDevice().GetRSSIs());