C++ :: Reserve Space For Array?
Oct 12, 2013
In my code I have a template class.
In the contructor, I create a new array arrray.
A pointer to this array is saved as an attribute.
The purpose of this attribute is that I should be able to call the array from within another function be typing *p or *(p+1) etc.
The only thing I forgot is that the array doesn't exist anymore when the constructor is done, right?
This means the space is no longer reserved for this array and the space is used for other things.
Is there a way to keep the array space reserved (even when the array does not exist anymore at the end of the function)?
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Nov 26, 2014
I have a situation where map elements will be inserted all throughout a continuous loop. I know that there's no reserve function for maps like there are for vectors, but I know exactly the maximum amount of elements there will be in the map, I just don't know the value of each individual map.
Would it be possible if I just inserted the maximum amount of elements in the beginning of the program, and change the value of each/any individual element later on? For example:
std::map<int, std::string> map;
//There will be a maximum of 200 elements in this map
for (int i = 0; i < 200; i++) {
map[i];
}
//Change the value of individual elements as I wish
Is it more efficient than initializing on declaration if initializing will be done often?
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Mar 7, 2014
We can construct vector in following ways
vector<int>v1; //create an empty vector
vector<int>v2(arr,arr+4); ///to create vector from an array
vector<int<v3(v2); //throuh copy constructor
But I have come across some program in a forum,they have create vector like this
vector<int>v(10,5)
I am clueless ,is this allowed?,what syntax allows this?
if a vector is create like this
vector<int>v(3);
v.push_back(1);
v.push_back(2);
v.push_back(3)
v.resize(2);
Now I am curious to know what are the changes those will happen in vector v because of resizing it?
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Sep 15, 2014
I am writing a program that minicks the library reserve system at my university and the problem is that when i run the code and reserve a room i am to keep track of the amount of times the room has been visited. To do this i set up a array roomcount and I count up by one every time i assign a room, The bug lies with when you reserve a room, then run option three, it will show that the previous visits is at 1, which is good. but then if i leave the room(option 2) and then run option 3 again to view the status of the rooms, the previous visits is set back to 0, which is not good. Ive been staring at this for hours and asked numerous people by we can't seem to figure out why the roomcount variable resets.
#include <stdio.h>
#include <math.h>
int main (void) {
int choice;
int roomchoice;
int i = 0;
[Code] .....
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Apr 29, 2014
I have a character Array 'Hello'
I want to add a space in whatever space the users chooses.
"Where do you want to add space? --> " 3 String after space is added --> 'Hel lo
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Jul 25, 2013
The assignment is to read a data file with a list of names, capitalize the first character of the first and last name by making an array and subtracting 32 from the character, and then outputting the names onto the screen. So far I have:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main () {
string line;
ifstream myfile ("Names.txt");
[Code] ....
this allows me to read a name, and capitalize the first letter of the first name. How to capitalize the first letter of the last name.
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May 14, 2013
How do you find the amount of space in a char array?
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Apr 7, 2013
I want to do this but do not know exactly how to do it:
Create an array of space ship objects and write a program that continually updates their positions until they all go off the screen. Assume that the size of the screen is 1024 pixels by 768 pixels.
I have begun to write a bit code but the problem is when you want to see the space ship moving step for step on the screen I do not know how to create the ship visible so you can see it is moving. Here's my code so far
Code:
#include <iostream>
using namespace std;
struct SpaceShips
{
int x_coordinate;
int y_coordinate;
[Code ......
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Sep 20, 2014
how to input with space what i mean is like this, for example:
Product Code: 0000001
Product Name: Mobile Phone
if the users input is like that in the (Product Name)it will skip the next input that is the
Price: Quantity: 100
Manufacturer: Alcatel
something like that...
Heres the code
Code:
if(b<=10)
{/*Start for IF Statement*/
for(a=1;a<=b;a++)
{/*Start of FOR loop*/
printf("
");
printf("Product Code : ");
scanf("%s", &prod_code);
}
[code]....
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Dec 2, 2014
I used pointer(or is it not?) to make it one part only alphabets and the other one digits. The coding, calculate_charges.c and the open file, customer.txt are attached at the end of the post.
Code:
#include <stdio.h>
#include <string.h>
#define SIZE 3
void trimback(char input[], int strnameindex);
void trimfrnt(char input[], int strnameindex);
}
[code]....
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Feb 1, 2013
What would the worst, average and best case space complexity be for a data structure of type map<string, vector<int> > in big O notation? I'm parsing through a document and storing each word as a key and im attaching an associated int (in a vector) to it as the value.
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Mar 16, 2013
Can we use using declaration within name space scope? is it safe to use it?
I think we can use using declaration for class scope and function scope only.
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Sep 24, 2014
I want the user to be able to enter a command then a character, like for example: push r....I want the command to be stored in the array command, and the character to be stored in the variable c.
Now I wonder what the best way to get rid of the space is, using scanf or getchar (see below for code, only thing that I changed between the 2 versions is the statement before the comment "get rid of space")? Or maybe it doesnt matter?
Code:
include <stdio.h>
#define MAX 200
void push(char c); // Puts a new element last in queue
char pop(void); // Gets the first element in queue
static char s[MAX];
}
[code]....
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Jan 15, 2013
I am allocating space only for two characters but it fits all of them, if you run this it will print the whole string literal "hello my friend". How is that possible?
I am using gcc 4.6.3., I know about strncpy().
#include<iostream>
#include<cstring>
using namespace std;
int main(){
char* str = new char[2];
strcpy(str, "hello my friend");
cout << str << endl;
return 0;
}
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Sep 26, 2013
how can I read some strings that contains spaces and put them in a vector of strings, using the push_back() function?
I have a collection of functions, for example: [multiply_by_forty two, add_by_five]. All I want to do is to store the strings like: multiply_by, add_by in a vector of strings, and the arguments:forty two, five etc in another vector of strings, but with spaces. The function convert() converts written numbers to numbers (for ex the output of covert("forty two")is 42;)
Here is the code:
public:void split() {
vector < string > s1;
vector < string > s2;
[Code].....
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Jun 8, 2013
I was coding a program that can count space, new_line, and other characters in a paragraph, but it doesn't work.
#include <stdio.h>
int main(void)
{
[Code].....
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Mar 24, 2014
I have a problem, caught the last line of a file and do the division of the same variables in, date, time and value, but the file contains excess spaces in all lines and the date is coming with cuts, example 24/4/2014 appears 4/4/2014. How can I remove the space in the string without affecting the division of the line?
if (file) {
std::string line = getLastLine(file);
std::istringstream iss(line);
getline(iss, date, ' ');
getline(iss, time, ' ');
getline(iss, t); //variavel para temperatura em string
}
else {
std::cout << "error file
";
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Apr 25, 2013
I'm really new to SDL and i've been trying to make a spaceshooter game, so far I've got a ship you can move around in using the arrow key (square shaped) and a scrolling background. I'm up to making my ship fire bullets at the moment and it's really not working, i've finished lazy foo's tutorials on SDL and there's nothing on this.
Here's my code
#include "SDL.h"
#include "SDL_image.h"
#include "SDL_mixer.h"
#include "SDL_ttf.h"
#include <string>
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;
[Code] .....
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Jan 23, 2014
I have created a prompt which prompts the user for an integer and I have set up a loop to check for if it is an integer or not. My "bug" is that a user can enter an "integer" and "space" and "enter" and it does not give any error and assumes that "All is FINE!". I have gotten the value from the ascii table of 'SPACE' and put it as a check in my parameter of while, but it does not work.
Here is my code:
int x, y, boolean, i;
char buff[256];
printf("Enter the first integer value: ");
scanf("%s", buff);
i = 0;
boolean = 0; //initializing our boolean var that will eventually decide if we have an error or not
[code]....
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Nov 13, 2014
I am having trouble finding out how to space out the binary numbers that I am displaying. Currently they are displaying all as one EX: 10001000
How can I get them to be space out properly like: 1000 1000?
Im guessing its something in my loop. Here's my function for converting to binary:
void DisplayBinary(int num) {
int ctr;
unsigned int mask = 32768;
printf("
The input number in binary is: ");
for (ctr = 1; ctr <= 16; ctr++) {
[Code] ....
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Mar 18, 2015
My code
#include<iostream>
#include<string>
using namespace std;
string strip(string message) { //removing elements that is not A-Z or a-z
string stripped;
for(int x = 0; x < message.length(); x++) {
[code]....
The output in my code shows like this:
[e]Encipher
[d]decipher
[x] Exit
Enter choice: e
Enter message to Encrypted:
i love you
Enter Key:
love
The encrypted message is: tzjzpmjy
Back to main menu? (y/n):
However , I want the output to display the spaces as the user's input.
ex. The encrypted message is: t zjzp mjy.
This is the same as i love you in the user's input.
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Feb 13, 2014
how to carry out the conversions. The assignment is the normal hex to octal and Quart (base 4) via bit munipulation which I have worked out myself. However, I have been trying all day to figure out how to read in a string such as H1234, or O4567. How to parse the input I can handle the remainder myself. I'm just stuck and I've tried for hours.
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Jan 23, 2013
this function has to check if an array is not descending it has to be recursive and it's space complexity has to be O(log(n))
Code:
int is_sorted(int a[ ], int n) {
int check=n-1;
if(n==1 || n==0) return 1;
if(a[check]<a[check-1])return 0;
else return(is_sorted(a,n-1));
}
this is what i came up with. i know it's space complexity is O(n) how do i make it O(log(n))?
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Sep 2, 2013
I was just going through Radix Sort algorithm. Though I got the logic and the concept used in it, I am still pretty much confused about the space complexity being O(k+n) for this algorithm. (where, k is the max no of digits in a number, and n is the no. of inputs to be sorted).
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Apr 20, 2013
I'm planning to make a C++ project using a 3D library to visualise space and planets, maybe using raytracing. I wanted to know which library is the most appropriate to achieve it.
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Aug 26, 2014
If every record of a binary file is to be fixed length then shouldn't some space be wasted if variables are different size in a struct?
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