I'm trying to overload an operator << so that it prints to a .txt file. Would these two codes basically do the same thing? If so, which one is the more efficient one to use?
ofstream& operator<<(ofstream& fout, const Grid& g);
ostream& operator<<(ostream & out, const Grid& g);
I've been working on a student data base that reads in the students name, birth date, social security, and department name (or major). I have all these items in the header files respectively; nameType, dateType, personType, and studentType.
I am now to create another header file called HWONEHEADER that contains the functions showMenu, loadStudent, insertStudent, searchByName, and SaveStudents. This is how far ive gotten
#ifndef HW
#define HW
#include <iostream>
#include <fstream>
#include <iomanip>
#include "studentType.h"
[Code] .....
Here is the cpp file i have.
int main() {
studentType department;
cin>>department;
cout<<department;
[Code] .....
I need with the HWONEHEADER using the ifstream and ofstream operators to load all the students information into a file called student.dat I'am extremely confused because i can't find anything in my textbook about using ifstream and ofstream operators.
I am using the following code to print in SDL screen
SDL_GL_RenderText( timer, font, color, &position);
sprintf(timer," Time : %d",time);
to print in SDL screen(used with opengl) , i am doing project on C++, as "sprintf" is C style function , so i can't do like this , i am trying to use" ostringstream" , but i am not sure how to use it.
I have a class called Point that has functions for getting and setting x, y, and z coords., distance, and midpoint. I need to write a function that prints the class and must use ostream & displayPoint( ostream & ); as the prototype. I did some googling and came up with
std::ostream& Point::displayPoint(std::ostream& out)
{
out << "(" << out.getx() << ", " << out.gety() << ", " << out.getz();
return out;
}
in order to print (x, y, z).
My IDE (Xcode) says "No member named 'getx' in std::__1::basic_ostream<char>"
I don't understand much about ostream reference
I have been trying to figure this out for a text based game. Lets say your money is 500. Then you save your game, but when you start the game the starting is 50, so when you load it, you still have 500 money, I tried lots of test, and im having trouble?
View 10 Replies View RelatedI'm using cout to print lots of lines. But i want to put together them in one variable etc. Then , i want to print it. I think i can do it with ostream but I cant do it . Is there any example use of ostream.
I want to use it such that:
x<< "hello" << endl;
x<< "mike" << endl;
x<< "how " << endl;
x<< "are" << endl;
x<< "you" << endl;
cout << x;
Will print
hello
mike
how
are
you
How can i do it?
I am trying to use ofstream to write in a txt file in a function called recurrently. for a simplified example:
void func_write(double x) {
ofstream myfile;
myfile << "the result = " << x << endl;
} int main() {
ofstream myfile;
[Code] .....
To this stage, it does not work, because the myfile in func_write cannot write in the txt file opened in main function. I don't want to open, append and close the txt file each time the function is called, that will take more time to execute all (imagine with 500 calls).
I am writing an eVoting program the addTally function adds 1 to the Candidate's voting tally when called and prints it back to the file from where it took the input replacing the old text. Now, Why I am getting error when running this program. Whenever i comment out the output file in addTally Function including where its used, it works.
Vote Function
void Vote(vector<int> &id_list, ofstream &voter_list) {
int ID;
bool valid_id;
char choice;
cout << " **** Voting Menu ****
[code]....
Function Adds one to the tally
void addTally(char choice) {
ifstream inCandidate("Candidates.txt");
ofstream outCandidate("Candidates.txt");
string Data_Line;
vector <string> Candidates;
string C_name[5];
int Tally[5];
[code]....
so this is part of a larger project but here is a test file that I haven't been able to get running. I don't understand why the minute I put an ofstream object as an instance variable the program flips out.
#include <iostream>
#include "FileNotFoundException.h"
int main() {
using namespace std;
try {
std::cout << "This is a test.";
throw FileNotFoundException("Testing...");
[code]....
The following code writes to a file on either local disk to a remote disk (commented out code) on Windows 7 platform.
Code:
#include <iostream>
#include <fstream>
using namespace std;
int main () {
ofstream outfile;
[Code].....
The documentation does not specify what is a valid filename (path and filename). For example, will the "\server emp" path work on all operating systems to access a samba share? Does the constructor accept forward and backward slashes as folder separator on all operating systems?
So the problem is that if you do launch << " Url = "http://google.com";
That C++ will detect that the second " is the end when really it isn't it is part of the VB script any way around this?
Then the second part that may be screwing this up is the // after the http.
Full code [URL] ....
I'm trying to move a dictionary into a group of bite-sized files based off of the length of the strings in each file (I'm ignoring strings of length 1 for obvious reasons). Since I don't know what the longest word is (and I'm not going to look for it), and I don't want redundant files, I decided to use a vector of output file streams that I would put all the words into, but I can't get the file to open.
I took a look at it and found the failbit is 1, but the badbit is 0, so apparently it's a logic error on opening the stream [URL] .... I looked online and decided to try using pointers, but that didn't work either, so now I'm asking what the problem might be, because I can't think of any reason why it isn't working.
void createDictionary() {
//declare variables
string dictionaryName;//name of dictionary file
ifstream dictionaryIn;//file of original dictionary
vector<shared_ptr<ofstream>> dictionaryOut;//files where dictionary will be put based off of word length
string word;//input from the dictionary file
vector<int> lengths;//vector containing available lengths and their locations
unsigned long long counter = 0;
[Code] ....
To generate output data, I'm printing a bunch of vector contents to files. Because the type of variable can differ between vectors, I wrote a templated printing function to print out whatever the content of the vector is. It looks like this:
template <class T>
void SomeClass::PrintVector(std::vector<T>& Values, std::string& outFile) {
std::ofstream out(outFile, std::ios::app);
[Code] ....
I added the fixed because some larger values were being printed in scientific notation. Everything works well. My test code includes 3 vectors of doubles and 3 vectors of unsigneds. All the unsigneds work well and two of the doubles work well, but the third doubles vector prints nonsense unless I disable the fixed.
The calling code is the exact same. I know the values in the vector are correct, because a) if I comment out the "fixed" flag it works, and b) one of the unsigned vectors is sorted based on the values in that double vector (after it is printed, so the sort cannot corrupt the vector print) and works perfectly.
The "nonsense" looks like chinese/weird characters, if that matters.
I have to output a series of data, I have to control the width of parts of my data. like following:
double a[] = {1.0, 2.0, 3.0};
double b[] = {1.5, 2.5, 3.5};
ofsteam myfile("result.txt");
for(int i=0; i<3; i++) {
myfile.width(5);
myfile << i+1 << " : " << a[i] << " - " << b[i] << end;
}
I only want to fix the width of a[i], b[i], but let the rest to be output normally.
how I can make it?
I'm having a little problem with std:fstream - in my program, the user selects the location of a file which I want to remember. So, I have something like this:
Code: std::string fileLocation;
//Code here creates an 'open file' dialog box which lets the user choose which file to open.
//The string 'fileLocation' now contains the path to the chosen file.
std::ofstream prefs("prefs.txt");
if (prefs.is_open())
{
prefs << fileLocation;
prefs.close();
}
This works fine if the file chosen is in the same directory as the program, however, if they try to choose a directory outside of where the program is kept, it saves the text file into that directory instead of the same one as the program. So, it looks like outputting a directory into an ofstream actually changes the location to which the file is saved.
Is there a way to save the file directory to a text file using ofstream and still have the text file save in the same directory as the program?
The + operator has left to right associativity then for the program f1() + f2(), why f1() is not called first compared to f2()?
View 5 Replies View RelatedI wrote this program using an online compiler i am getting a lot of errors.
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main() {
string birthmonth;
string birthday;
[Code] ....
I have a code that uses multi threads using OMP. However, Inside the code I allocate too many memory using "new".
I know that the memory allocation using new must be done in serial. Therefore I am not getting a good performance out of the multi-threaded program.
I thought about allocating a big memory only once, and then advance the pointer every time I need to allocate a small memory.
For example, if I need to allocate chunks of 7 doubles:
Code:
main_memory = new double [10000];
double* x1 = main_memory;
main_memory+= 7;
double* x2 = main_memory;
main_memory+= 7
However, I do not know how to handle the memory deallocation. Beside, this is not thread safe method because main_memory is shared by all threads.
May be there is a boost library that does this, which I am not aware of.
I have two class GameOfLife and Cell and i want to overload square braket for class GameOfLife."if g is a GameOfLife object, g[10][5] will return the Cell at row 10 and column 5. If there is no such Cells, then it will return a new Cell with position (-1000,- 1000)."
but if g[10][1000] and 1000>cols,then it returns different Cell exp (3,2) How i do control the col ( [row][col] )?
Code: vector<Cell> GameOfLife::operator [](const int row){
vector<Cell> rowCell;
for(int i=0; i<cols; ++i)
{
if( isLive(row,i) )
rowCell.push_back( Cell(row,i) );
else
rowCell.push_back( Cell(-1000,-1000) );
}
return rowCell;
}
Came across the foll code:
#include<stdio.h>
main() {
int i=4,j=7;
j=j||(printf("you can")&&(i=5));
printf("%d %d",i,j);
}
output: 4 1
Although I am specifying the braces for the && operator so that it gets executed first..Then also the value of i remains 4 only..Why does not it gets changed to 5??Also the printf does not execute??
Switch case statements are a substitute for long if statements that compare a variable to several "integral" values ("integral" values are simply values that can be expressed as an integer, such as the value of a char).
So does that mean switch statements can only test if variable == value and nothing more, like > < >= <= != etc... ? I tried to make a program to test this and it seems like switch statements are limited to == but I'm not sure, maybe I'm doing something wrong.
This is the program I tried to make to test this:
Code:
#include <stdio.h>
int main () {
int n;
[Code]....
So is it true that switch statements only work with the built in == operator? if that was the case then I would feel rather meh about switch statements.
I have a small piece of code that used the set::insert function on a set of myClass. For that, I need to overload the < and > operators, which I have, but I still get a huge error saying it can't compare.
set<MyClass> mySet;
MyClass myClass
All the class information gets filled in. Then, I try to insert...
mySet.insert(myClass);
bool operator<(MyClass &lhs, MyClass &rhs) {
return lhs.name < rhs.name; //name is a string
}
The error says
...stl_function.h:230:22: error: no match for 'operator<' in '__x < __y'
MyFile.h:80:6: note: candidate is bool operator<(MyClass&, MyClass&)
I'm experimenting with a custom memory-pool for my application, and I initially planned to override the global new and delete operators to allocate memory in this pool. But since I'm using QT, this will apply to all the QT-related stuff as well. Should I instead just override the new and delete operators per class?
View 2 Replies View RelatedI have two files NumDays.h and ClientProgram.cpp
clientprogram.cpp basically has the main module below
int main(){
// Initialized UDT object Declarations
NumDays hoursWorked_John; // Instantiate with Default Constructor
NumDays hoursWorked_Sue(36.9); // Instantiate with Initializing Constructor
NumDays hoursUsed_Sue(4.5); // Instantiate with Initializing Constructor
[Code] .....
I can't figure out anything to put in for NumDays.cpp so it's not there.
In the following program.
void main() {
int a=1;
cout<<a++<<" "<<++a<<" "<<a++<<endl;
}
If I execute the above program i should get 1 3 3. But I'm getting different values when I executed this program. The values that I get after execution are 3 3 1.
I made a program that allows the user to enter information of credit cards on an array of size 5, however I need to allow the user to compare the five credit cards with each other and I am having problems with this particular part. I made my bool operator functions for the operator< and the operator> but how to make the user be able to select which cards he wants to compare and how to compare them. My code is the following:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
const int SIZE = 5;
enum OPCIONES {CARGAR=1, ABONAR, NADA};
[Code] ......