I have this code:
int do_transact(ifstream & inFile, list<shared_ptr<Bike>> bikelist, status s)
{
int id, i = 0, size = bikelist.size();
float days;
string str, str2;
char name[50];
list<shared_ptr<Bike>>::iterator it = bikelist.begin();
if (s == NO_STATUS) //performs rental
{
inFile >> id;
inFile >> days;
inFile >> str;
inFile >> str2;
strcpy_s(name, str.c_str());
while (i < size)
{
if (id == (*it)->id_num) // rents bike
{
cout << "vvvvvv PERFORMING RENTAL vvvvvv" << endl << endl;
cout << "The price of this rental will be: $" << (days)*((*it)->cost_per_day) << endl;
strcpy_s((*it)->to_whom, name);
(*it)->rented_code = RENTED;
cout << "Thank you for your business!" << endl << endl;
return 0;
}
i++;
it++;
}
}
}
I am trying to change to_whom and rented_code in the original list, but it is not updating.
What is the syntax I need in order to change these values the way I need?
Related
I am passing map by reference in the canSum function where i am mutating its value and adding pairs but at the end when I iterate over the map I find the value of map has not been updated.
canSum function is a recursive function which takes a number (targetSum) and an array and finds if it is possible to form targetSum by any combinations of number in the array (numbers can be repeated).
#include<iostream>
#include<vector>
#include<map>
using namespace std;
bool canSum(int targetSum,vector<int> a,map<int, bool> &m){
if(!(m.find(targetSum) == m.end()))
return m[targetSum];
if (targetSum == 0)
return true;
if(targetSum<0)
return false;
for (int num : a)
{
if (canSum(targetSum - num, a,m)==true)
{
// m[targetSum] = true;
m.insert(pair<int, bool>(targetSum, true));
return m[targetSum];
}
}
m[targetSum] = false;
return m[targetSum];
}
int main(){
int targetSum, t;
vector<int> a;
map<int, bool> m;
m[0] = true;
cout << "enter target" << endl;
cin >> targetSum;
cout << "enter array, press esc to stop entering"<<endl;
while(cin>>t){
a.push_back(t);
}
for (int j = 0; j < a.size(); j++)
{
cout << a[j]<<" ";
}
cout << endl;
for (auto itr = m.begin(); itr != m.end(); ++itr) {
cout << '\t' << itr->first
<< '\t' << itr->second << '\n';
}
if(canSum(targetSum, a,m)){
cout << endl << "true" << endl;
}
else cout << endl << "false" << endl;
return 0;
}
Please help me. Thank you.
The for loop to print the map should be after the function call like.
if(canSum(targetSum, a,m)){
cout << endl << "true" << endl;
}
else cout << endl << "false" << endl;
for (auto itr = m.begin(); itr != m.end(); ++itr) {
cout << '\t' << itr->first
<< '\t' << itr->second << '\n';
}
Instead of
for (auto itr = m.begin(); itr != m.end(); ++itr) {
cout << '\t' << itr->first
<< '\t' << itr->second << '\n';
}
if(canSum(targetSum, a,m)){
cout << endl << "true" << endl;
}
else cout << endl << "false" << endl;
To see mutations in the map due to the function
i've seen this interesting method to encrypt/decrypt messages with RSA on YouTube and it works, I've tested it : https://www.youtube.com/watch?v=tXXnHXslVhw&t=98s minute 1:45 . I am not that good at math, is there a name for what this guy is doing?
void En() {
crypted= text;
unsigned long long temp=0;
unsigned long long enc = 0;
for (int i = 0; i < text.length() / 2; i++)
{
if (text[i]>='a' && text[i] <= 'z')
{
temp = (text[i] - 96) * 26 + text[i + 1] - 96;
enc = pow(temp, public_key);
enc= enc % N
cout << enc << endl;
enc_v2 = enc;
}
}
cout << "Enc: " << enc << endl;}
void De() {
unsigned long long temp2 = 0;
unsigned long long temp = 0;
char ch=' ', ch2=' ';
for (int i = 0; i < text.length()/2; i++)
{
cout << enc_v2 << private_key;
temp = pow(enc_v2, private_key);
cout << "Temp :" << temp;
temp = temp % N;
cout << "Temp modulo :" << temp;
temp2 = temp;
temp = temp / 26;
cout << " Temp char 1 :"<< temp;
ch = temp + 96;
temp2 = temp2 - temp * 26;
cout << " Temp char 1 :" << temp2;
ch2 = temp2 + 96;
}
cout << "Text: " << ch << ch2;}
P.S. I know about the pow and modular exponentiation , this in only to show what he is doing.
Thank you!
So I am trying to send floats back and forth between clients and a server. I am able to send floats to the server and the server reads them perfectly. But unfortunately I can't seem to get the server sending the floats back to the other clients. Our current code that doesn't work looks like this.
Send function on server side
int Server::Send(float dt) {
{
char message[BUFLEN];
std::string msg = std::to_string(x2) + "#" + std::to_string(z2);
strcpy(message, (char*)msg.c_str());
if (sendto(server_socket, message, sizeof(message), 0, ptr->ai_addr, ptr->ai_addrlen) == SOCKET_ERROR)
{
std::cout << "Sendto() failed..." << std::endl;
}
else
{
std::cout << "Sent: " << message << "\n" << std::endl;
}
Receiving on Client side
int Client::Recieve(float dt) {
char buf[BUFLEN];
struct sockaddr_in fromAddr;
int fromlen;
fromlen = sizeof(fromAddr);
memset(buf, 0, BUFLEN);
int bytes_recieved = -1;
int sError = -1;
bytes_recieved = recvfrom(client_socket, buf, BUFLEN, 0, (struct sockaddr*) &fromAddr, &fromlen);
sError = WSAGetLastError();
if (sError != WSAEWOULDBLOCK && bytes_recieved > 0)
{
std::cout << "Recieved: " << buf << std::endl;
std::string tmp = buf;
std::size_t pos = tmp.find("#");
tmp = tmp.substr(0, pos - 1);
x2 = std::stof(tmp, NULL);
tmp = buf;
tmp = tmp.substr(pos + 1);
z2 = std::stof(tmp, NULL);
std::cout << "tx: " << x2 << " ty: " << z2 << std::endl;
}
else
std::cout << "Not Receiving" << std::endl;
Any help would be awesome!
I'm trying to read in multiple element types from a text file.
Here's an example input:
push 0
push 1
push 3
push 5
add
push 3
The code below work until the last line, then I get a BAD_ACCESS error after trying anything after it reads in a line without 'b'. Any suggestions?
ifstream infile("example.txt");
while (!infile.eof())
{
infile >> a >> b;
if (a == "push")
push(b);
if (a == "add")
{
add();
}
if (a == "subtract")
{
int y = subtract();
cout << y << endl;
}
if (a == "multiply")
{
int y = multiply();
cout << y << endl;
}
if (a == "divide")
{
int y = divide();
cout << y << endl;
}
if (a == "pop")
{
cout << b;
b = NULL;
}
cout << a << b << endl;
}
I want to delete items out of my QMultiHash. Looking at the docs, I believe I am doing it correctly but it always crashes after the first delete. What am I doing wrong?
Here is my code:
for (QMultiHash<int, Frame*>::iterator i = m_FrameBuffer.begin(); i != m_FrameBuffer.end(); ++i) {
if ( (frameNumber - i.key()) >= ( 5 ) ) { // Delete frames 5 frames old or more
qDebug() << "DELETE ==> Key:" << i.key() << "Value:" << i.value() << " Difference: " << (frameNumber - i.key());
int removed = m_FrameBuffer.remove(i.key());
qDebug() << "Removed this many: " << removed;
}
}
Here is the output:
FRAME COUNT: 1
FRAME COUNT: 2
FRAME COUNT: 3
FRAME COUNT: 4
FRAME COUNT: 5
DELETE ==> Key: 2 Value: Frame(0x138a400) Difference: 5
Removed this many: 1
The program has unexpectedly finished.
Your iterator becomes invalid after you remove items from a container while iterating it. Try this:
QList<int> keys = m_FrameBuffer.keys();
foreach (int key, keys)
{
int diff = frameNumber - key;
if (diff >= 5)
{
qDebug() << "DELETE ==> Key:" << key
<< "Value:" << m_FrameBuffer.value(key)
<< "Difference: " << diff;
int removed = m_FrameBuffer.remove(key);
qDebug() << "Removed this many: " << removed;
}
}
Also you can use QMutableHashIterator for it:
QMutableHashIterator<int, Frame*> it(m_FrameBuffer);
while (it.hasNext())
{
it.next();
int key = it.key();
int diff = frameNumber - it.key();
if (diff >= 5)
{
qDebug() << "Items to be removed:"
<< m_FrameBuffer.values(it.key()).size();
it.remove();
}
}