If I prompt the user for n number of printers, is there a way of creating n number of vectors on the fly as opposed to creating vectors and putting them in your class structure at the start?
I have to create as many printer queues as a user specifys. I am using vectors for this. I am planning to put them into a class structure.
Thanks.
Jump to PostYou can have a vector of vectors
vector< vector<MyClass> > printerList;
Jump to Post
vector<vector<PCB> > printers(3, vector<PCB>()); // 3 vectors
Jump to PostThe above code could be more succinctly written as
vector<vector<PCB> > printers(input);
Jump to PostHere's a simple example:
#include <iostream> #include <vector> #include <string> class MyClass { public: MyClass(std::string arg = "default") : m_arg(arg) {} void display() const { std::cout << m_arg << std::endl; } private: std::string m_arg; }; int main() { size_t n = 0; // assuming valid input for …
You can have a vector of vectors
vector< vector<MyClass> > printerList;
Thanks! Let me see if I can figure out how to implement that.
I tried a few things and they're not working.
Let's say I have this: vector< vector<PCB> > printers;
How do I create n vectors out of this?
int input;
cin >> input;
Where would I use input to create the vectors?
Thanks.
vector<vector<PCB> > printers(3, vector<PCB>()); // 3 vectors
Thank you. I tried it in my code and it didn't cause an error.
How to I write to and read from each vector now? What is the syntax I'll need?
The above code could be more succinctly written as vector<vector<PCB> > printers(input);
I see, thanks! I'll try that.
So, let's say I want to push back a value to printer 1 as opposed to printer 2 if input is 2 and 2 vectors are created? What is the syntax to differentiate between each vector?
Here's a simple example:
#include <iostream>
#include <vector>
#include <string>
class MyClass {
public:
MyClass(std::string arg = "default") : m_arg(arg) {}
void display() const {
std::cout << m_arg << std::endl;
}
private:
std::string m_arg;
};
int main()
{
size_t n = 0;
// assuming valid input for brevity
std::cout << "Enter the number of vectors (at least 3): ";
std::cin >> n;
std::vector<std::vector<MyClass> > classes_vector(n);
MyClass mc("This is first");
MyClass mca("This is also first");
MyClass mc1("This is second");
MyClass mc2("This is third");
classes_vector[0].push_back(mc);
classes_vector[0].push_back(mca);
classes_vector[1].push_back(mc1);
classes_vector[2].push_back(mc2);
for (auto cl : classes_vector[0])
{
cl.display();
}
for (auto cl : classes_vector[2])
{
cl.display();
}
// simple flush
std::cin.ignore(90, '\n');
std::cin.get();
return 0;
}
Thanks.
I tried it but am having the following issue:
When I try to access private member tau in the PCB class with the getTau() member function through readyQueues[0].getTau() at line 241, I get an error message stating:
[Error] 'class std::vector<PCB>' has no member named 'getTau'
Here is the code:
#include <iostream>
#include <string>
#include <limits>
#include <vector>
#include <iomanip>
#include <cstdlib>
using namespace std;
/**
* Global Variables
*/
string k;
int pmem, plen;
int dmem, dlen;
int cmem, clen;
string dname, pname, cname, drw, prw, crw;
int g_pid = 0;
float tempTau;
/**
* Process Control Block Class
*/
class PCB
{
public:
PCB() : pid (0), filename ( "InitialString" ), memoryLocation ( 0 ), rw ( "InitialString" ), fileLen ( 0 ), procTime( 0 ), tau( 0 ) { }
void setPid( int p );
int getPid() const;
void setFilename( string f );
string getFilename() const;
void setMemoryStart( int m );
int getMemoryStart() const;
void setFileLength( int l );
int getFileLength() const;
void setRW( string r );
string getRW() const;
void setTime( float t );
float getTime() const;
void setTau( float t );
float getTau() const;
void setAlpha( float a );
float getAlpha() const;
void setCylin( int cc );
int getCylin() const;
//float calculate();
float calculateTau();
void setCpuTime( float c );
float getCpuTime() const;
private:
int pid;
string filename;
int memoryLocation;
string rw;
int fileLen;
int procTime;
int cylinder;
float tau;
static float alpha;
float cpuTime;
static float time;
};
/*
* Computer structure
*/
struct computer
{
int printer;
int disk;
int cd;
int num;
vector<PCB> readyQueue;
vector<PCB> diskQueue;
vector<PCB> diskQueueCopy;
vector<PCB> printerQueue;
vector<PCB> printerQueueCopy;
vector<PCB> cdQueue;
vector<PCB> cdQueueCopy;
vector<int> time;
vector<PCB> vCylinder;
vector< vector<PCB> > printerQueues;
void screen();
void prompt();
void runningPrompt();
void calculate();
int & findMin( vector<int> & v );
int findPos( vector<int> & vv );
void removeElem();
};
/**
* Sys Gen Process begins here. Prompt the user for input.
*/
void computer::prompt()
{
cout << "Welcome to the Sys Gen Process"<<endl;
cout<<"Please enter the number of printers in the system (between 1 and 9)"<<endl;
while( ! ( cin >> printer ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
while(printer<1 || printer>9)
{
cout<<"Sorry, that is an invalid value, please re-enter amount of printers:"<<endl;
while( ! ( cin >> printer ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
}
vector<vector<PCB> > printerQueues( printer ); // 3 vectors
cout<<"Thank you. Please enter the number of disks in the system (between 1 and 9)"<<endl;
while( ! ( cin >> disk ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
while(disk<1 || disk>9)
{
cout<<"Sorry, that is an invalid value, please re-enter amount of disks:"<<endl;
while( ! ( cin >> disk ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
}
cout<<"Please enter the number of CD/RW's in the system (between 1 and 9)"<<endl;
while( ! ( cin >> cd ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
while(cd<1 || cd>9)
{
cout<<"Sorry, that is an invalid value, please re-enter amount of CD/RW's:"<<endl;
while( ! ( cin >> cd ) )
{
cout << "That was not an integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
}
cout << "Please enter an initial burst tau: " << endl;
PCB t;
string inputTau;
cin >> inputTau;
tempTau = atof(inputTau.c_str());
while( tempTau <= 0 )
{
cout << "Please enter a value such as 0.9" << endl;
cin >> inputTau;
tempTau = atof(inputTau.c_str());
}
t.setTau( tempTau );
cout << "Please enter a value for alpha: " << endl;
string inputAlpha;
float tempAlpha;
cin >> inputAlpha;
tempAlpha = atof(inputAlpha.c_str());
while( tempAlpha <= 0 )
{
cout << "Please enter a value such as 0.9" << endl;
cin >> inputAlpha;
tempAlpha = atof(inputAlpha.c_str());
}
t.setAlpha( tempAlpha );
cout << "Please enter how many cylinders for each disk: " << endl;
string inputCylinder;
int tempCylinder;
for( int i = 1; i < disk + 1; i++ )
{
cout << "Disk[" << i << "]:" << endl;
cin >> inputCylinder;
tempCylinder = atof(inputCylinder.c_str());
while( tempCylinder <= 0 )
{
cout << "Please enter an integer value: " << endl;
cin >> inputCylinder;
tempCylinder = atof(inputCylinder.c_str());
}
t.setCylin( tempCylinder );
vCylinder.push_back( t );
}
}
/**
* This runningPrompt Function receives input from the keyboard regarding processes
*/
void computer::runningPrompt()
{
cout << "You may enter a command or type 'exit' to exit the system." << endl;
PCB process;
while (k != "exit")
{
cout << "Please enter command: ";
cin >> k;
if( k[0] == 'A' )
{
if( !readyQueue.empty() )
{
cout << "Interrupt detected" << endl;
cout << "How long? " << endl;
string inputTime;
cin >> inputTime;
int timeTemp;
timeTemp = atof( inputTime.c_str());
while( timeTemp <= 0 )
{
cout << "Please enter an integer value: " << endl;
cin >> inputTime;
timeTemp = atof(inputTime.c_str());
}
g_pid++;
process.setPid( g_pid );
process.setTau( timeTemp );
readyQueue.push_back( process );
}
else
{
cout << "New Process created." << endl;
g_pid++;
process.setPid( g_pid );
process.setTau( tempTau );
readyQueue.push_back( process );
}
calculate();
}
if( k[0] == 'L' ) // this is a test construct
{
PCB j;
printerQueues[0].push_back( j );
cout << printerQueues[0].getTau() << endl;
//cout << j.getTau() << endl;
//cout << j.getAlpha() << endl;
//j.calculate();
//cout << j.getTau() << endl;
//cout << readyQueue[0].calculate() << endl;
//cout << readyQueue[1].calculate() << endl;
}
if( k[0] == 't' )
{
if( !readyQueue.empty() )
{
cout << "Process terminating." << endl;
readyQueue.erase( readyQueue.begin() );
}
else
{
cout << "Ready queue is empty." << endl;
}
}
if( k[0] == 'S' )
{
screen();
}
if( k[1] == '1' )
num = 1;
if( k[1] == '2' )
num = 2;
if( k[1] == '3' )
num = 3;
if( k[1] == '4' )
num = 4;
if( k[1] == '5' )
num = 5;
if( k[1] == '6' )
num = 6;
if( k[1] == '7' )
num = 7;
if( k[1] == '8' )
num = 8;
if( k[1] == '9' )
num = 9;
if ( k[0] == 'd' )
{
if( disk >= num )
{
if( !readyQueue.empty() )
{
cout << "This is a system call requesting Disk " << num << endl;
cout << "What is the filename? Please enter it: " << endl;
cin >> dname;
process.setFilename( dname );
cout << "What is the starting location in memory? Please enter it:" << endl;
while( ( ! ( cin >> dmem ) ) || dmem < 0 )
{
cout << "That was not a positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setMemoryStart( dmem );
cout << "Please enter the length of your file in an integer value:" << endl;
while( ( ! ( cin >> dlen ) ) || dlen < 0 )
{
cout << "That was not positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setFileLength( dlen );
cout << "Please enter r for read or w for write" << endl;
cin >> drw;
while( ! ( drw == "r" || drw == "w" ) )
{
cout << "Please enter a r or a w" << endl;
cin >> drw;
}
process.setRW( drw );
process.setPid( readyQueue.front().getPid() );
diskQueue.push_back( process );
readyQueue.erase( readyQueue.begin());
}
else
{
cout << "There are no processes in the ready queue." << endl;
}
}
else
{
cout << "Please enter a valid disk number" << endl;
}
}
if ( k[0] == 'p' )
{
if( printer >= num )
{
if( !readyQueue.empty() )
{
cout << "This is a system call requesting printer: " << num << endl;
cout << "What is the filename? Please enter it: " << endl;
cin >> pname;
process.setFilename( pname );
cout << "What is the starting location in memory? Please enter it:" << endl;
while( ( ! ( cin >> pmem ) ) || pmem < 0 )
{
cout << "That was not a positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setMemoryStart( pmem );
cout << "Please enter the length of your file in an integer value:" << endl;
while( ( ! ( cin >> plen ) ) || plen < 0 )
{
cout << "That was not positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setFileLength( plen );
process.setPid( readyQueue.front().getPid() );
printerQueue.push_back( process );
readyQueue.erase( readyQueue.begin());
}
else
{
cout << "There are no processes in the ready queue." << endl;
}
}
else
{
cout << "Please enter a valid printer number" << endl;
}
}
if ( k[0] == 'c' )
{
if( cd >= num )
{
if( !readyQueue.empty() )
{
cout << "This is a system call requesting CD/RW: " << num << endl;
cout << "What is the filename? Please enter it: " << endl;
cin >> cname;
process.setFilename( cname );
cout << "What is the starting location in memory? Please enter it:" << endl;
while( ( ! ( cin >> cmem ) ) || cmem < 0 )
{
cout << "That was not a positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setMemoryStart( cmem );
cout << "Please enter the length of your file in an integer value:" << endl;
while( ( ! ( cin >> clen ) ) || clen < 0 )
{
cout << "That was not positive integer...\nTry again: ";
cin.clear();
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
}
process.setFileLength( clen );
cout << "Please enter r for read or w for write" << endl;
cin >> crw;
while( ! ( crw == "r" || crw == "w" ) )
{
cout << "Please enter a r or a w" << endl;
cin >> crw;
}
process.setRW( crw );
process.setPid( readyQueue.front().getPid() );
cdQueue.push_back( process );
readyQueue.erase( readyQueue.begin() );
}
else
{
cout << "There are no processes in the ready queue." << endl;
}
}
else
{
cout << "Please enter a valid CD/RW number. " << endl;
}
}
if( k[0] == 'D' )
{
if( !diskQueue.empty() )
{
readyQueue.push_back( process );
diskQueue.erase( diskQueue.begin() );
}
else
{
cout << "The disk queue is empty. " << endl;
}
}
if( k[0] == 'P' )
{
if( !printerQueue.empty() )
{
readyQueue.push_back( process );
printerQueue.erase( printerQueue.begin() );
}
else
{
cout << "The printer queue is empty. " << endl;
}
}
if( k[0] == 'C' )
{
if( !cdQueue.empty() )
{
readyQueue.push_back( process );
cdQueue.erase( cdQueue.begin() );
}
else
{
cout << "The CD/RW queue is empty. " << endl;
}
}
}
}
/**
* User can get a "Screen Shot" but typing "S" at command line.
*/
void computer::screen()
{
PCB p1;
cout << "Taking Snapshot." << endl;
cout << "Please select r, d, p, or c." << endl;
string rpdc;
cin >> rpdc;
while ( ! ( rpdc[0] == 'r' || rpdc[0] == 'p' || rpdc[0] == 'd' || rpdc[0] == 'c' ) )
{
cout << "Please enter r, p, d, or c. Thank you." << endl;
cout << "Enter selection" << endl;
cin >> rpdc;
}
if( rpdc[0] == 'r' )
{
cout << left << setw(9) << "PID" << left << setw(14) << "Filename"
<< left << setw(14) << "Memstart" << " R/W" << endl;
if( !readyQueue.empty() )
{
for( int i = 0; i < readyQueue.size(); i++ )
{
cout << left << setw(0) << "" << readyQueue[i].getPid() << left << setw(4) << " "
<< left << setw(14) << " " << left << setw(14) << " "
<< left << setw(14) << " " << " " << " " << endl;
}
}
else
{
cout << left << setw(0) << "" << "0" << left << setw(4) << " "
<< left << setw(14) << " " << left << setw(14) << " "
<< left << setw(14) << " " << " " << endl;
}
}
if( rpdc[0] == 'p' )
{
PCB l;
//cout << l.calculate() << endl;
//cout << l.calculateTau() << endl;
/*for( int i = 0; i < vCylinder.size(); i++ )
{
cout << vCylinder[i].getCylin() << endl;
} // This works <--------------------------------------------------*/
for( int i = 0; i < readyQueue.size(); i++ )
{
cout << readyQueue[i].getTau() << endl;
}
calculate();
cout << readyQueue[0].getTau() << endl;
cout << left << setw(8) << "PID" << setw(14) << "Filename"
<< setw(14) << "Memstart" << setw(14) << "FileLen" << " R/W" << endl;
if( !printerQueue.empty() )
{
for( int i = 0; i < printerQueue.size(); i++ )
{
cout << setw(0) << "p" << printerQueue[i].getPid() << setw(6) << " "
<< setw(14) << printerQueue[i].getFilename() << setw(14) << printerQueue[i].getMemoryStart()
<< setw(14) << printerQueue[i].getFileLength() << " - " << endl;
}
}
else
{
cout << left << setw(0) << "" << "0" << left << setw(4) << " "
<< left << setw(14) << " " << left << setw(14) << " "
<< left << setw(14) << " " << " " << endl;
}
}
if( rpdc[0] == 'd' )
{
cout << left << setw(8) << "PID" << left << setw(14) << "Filename"
<< left << setw(14) << "Memstart" << left << setw(14) << "FileLen" << " R/W" << endl;
if( !diskQueue.empty() )
{
for( int i = 0; i < diskQueue.size(); i++ )
{
cout << setw(0) << "d" << diskQueue[i].getPid() << setw(6) << " "
<< setw(14) << diskQueue[i].getFilename() << setw(14) << diskQueue[i].getMemoryStart()
<< setw(14) << diskQueue[i].getFileLength() << diskQueue[i].getRW() << endl;
}
}
else
{
cout << left << setw(0) << "" << "0" << left << setw(4) << " "
<< left << setw(14) << " " << left << setw(14) << " "
<< left << setw(14) << " " << " " << endl;
}
}
if( rpdc[0] == 'c' )
{
cout << left << setw(8) << "PID" << left << setw(14) << "Filename"
<< left << setw(14) << "Memstart" << left << setw(14) << "FileLen" << " R/W" << endl;
if( !cdQueue.empty() )
{
for( int i = 0; i < cdQueue.size(); i++ )
{
cout << left << setw(0) << "c" << cdQueue[i].getPid() << left << setw(5) << " "
<< left << setw(14) << cdQueue[i].getFilename() << left << setw(14) << cdQueue[i].getMemoryStart()
<< left << setw(14) << cdQueue[i].getFileLength() << cdQueue[i].getRW() << endl;
}
}
else
{
cout << left << setw(0) << "" << "0" << left << setw(4) << " "
<< left << setw(14) << " " << left << setw(14) << " "
<< left << setw(14) << " " << " " << endl;
}
}
}
/**
* Member function definititions follows:
*/
void PCB::setPid(int p)
{
pid = p;
}
int PCB::getPid() const
{
return pid;
}
void PCB::setFilename( string f )
{
filename = f;
}
string PCB::getFilename() const
{
return filename;
}
void PCB::setMemoryStart( int m )
{
memoryLocation = m;
}
int PCB::getMemoryStart() const
{
return memoryLocation;
}
void PCB::setFileLength( int l )
{
fileLen = l;
}
int PCB::getFileLength() const
{
return fileLen;
}
void PCB::setRW( string r )
{
rw = r;
}
string PCB::getRW() const
{
return rw;
}
void PCB::setTime( float t )
{
time = t;
}
float PCB::getTime() const
{
return time;
}
int & computer::findMin( vector<int> & v )
{
int minIndex = 0;
for( int i = 1; i < v.size( ); i++ )
if( v[ minIndex ] > v[ i ] )
minIndex = i;
return v[ minIndex ];
}
int computer::findPos( vector<int> & v )
{
int minIndex = 0;
for( int i = 1; i < v.size( ); i++ )
if( v[ minIndex ] > v[ i ] )
minIndex = i;
return minIndex;
}
void computer::removeElem()
{
time.erase( time.begin() + ( findPos( time ) ) );
}
void PCB::setTau( float t )
{
tau = t;
}
float PCB::getTau() const
{
return tau;
}
void PCB::setAlpha( float a )
{
alpha = a;
}
float PCB::getAlpha() const
{
return alpha;
}
void PCB::setCylin( int cc )
{
cylinder = cc;
}
int PCB::getCylin() const
{
return cylinder;
}
void computer::calculate()
{
float t;
t = ( readyQueue[0].getTau() - readyQueue[1].getTau());
readyQueue[0].setTau( t );
}
float PCB::calculateTau()
{
float f;
f = ( (getAlpha() * getTau()) + (getAlpha() * getTime()) );
return f;
}
void PCB::setCpuTime( float c )
{
cpuTime = c;
}
float PCB::getCpuTime() const
{
return cpuTime;
}
float PCB::alpha = 0;
float PCB::time = 0;
/**
* main() begins here--
*/
int main()
{
computer c;
c.prompt();
c.runningPrompt();
return 0;
}
readyQueues[0] is the vector, so you need to specify which element (PCB instance) of the vector you wish to access.
e.g.
printerQueues[0][0].getTau();
printerQueues[0].at(0).getTau();
printerQueues[0].front().getTau();
printerQueues[0].back().getTau();
As an aside, assuming you are using ASCII character encoding (or something else with digits in order, such as UTF-8), you can simplify the section in lines 265-282 as:
if (isdigit(k[1]) && k[1] != '0')
num = k[1] - '1';
It isn't a huge improvement, but it should make it more readable. You'll need to #include <cctype> at the start of the source file. If you actually do want it to set it when zero, simply remove the second part of the conditional cluase.
Thanks nullptr and Schol-R-LEA.
nullptr, I have tried all 4 of you suggestions above and they all cause a segmentation fault. They all compile however.
Thanks.
Is the issue the way I am trying to fill the vectors at line 115?
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