So I have a vector that I want to iterate through randomly, and by random I mean that each element is only accessed once but I don't want to shuffle the vector because the vector elements are large. So I want this functionality:
std::vector<SomeLargeObjectWithoutACopyConstructor> myvec;
// ...fill myvec
std::random_shuffle(myvec.begin(),myvec.end());
for (auto& value : myvec)
{
// do stuff
}
Only I don't want to do this because the object type has no copy constructor and is large, so I don't want to shuffle the vector, just the iteration path. Is there a simple and efficient way of iterating randomly through a vector while ensuring that each object is only accessed once?
I'm having trouble getting my loop to work correctly. If I iterate the for loop once it works as expected and displays proper output. When I try to iterate two times or more the program gets stuck in an infinite loop.
What happens is, after having called the collisionDestroy-function and the program tries to execute the nest loop in the outer for-loop, it all crashes with the text "Expression: vector iterator not decrementable", which I understand is because the iterator will have already become useless. The question is: know this, how do I fix it? I can't seem to get a hang of it.
Here's the collisionDestroy-function (the collisionReaction does nothing but sets a few local variables):
void Enemy::collisionDestroy(std::vector<Sprite*>& sprites) { for (std::vector<Sprite*>::iterator iter = sprites.begin(); iter != sprites.end(); iter++) { Enemy* tmp = dynamic_cast<Enemy*>(*iter); if (this == tmp && collisionType == 3 || collisionType == 1) { sprites.erase(iter); break; } } }
Ok here I have a program that reads a word from a text file randomly and matches it with the definition. The user has to guess what the word is according to the definition.
I'm having trouble with my for loop, I'm not getting any errors. But I just know something is off.
using namespace std; int main(){ int number; int count = 0; int numOfGuess = 0;
[Code] ...
This is words.txt:
apple#the usually round, red or yellow, edible fruit of a small tree boat#a vessel for transport by water horse#a solid-hoofed plant-eating domesticated mammal with a flowing mane and tail, used for riding television#a system for transmitting visual images and sound that are reproduced on screens soup#a liquid dish, typically made by boiling meat, fish, or vegetables, etc. bottle#a container, typically made of glass or plastic and with a narrow neck barber#a person who cuts hair toast#sliced bread browned on both sides by exposure to radiant heat radar#a system for detecting the presence, direction, distance, and speed of aircraft, ships, and other objects red#of a color at the end of the spectrum next to orange and opposite violet
Lexer.cpp: In member function 'void Lexer::PrintSource()': Lexer.cpp:29:42: error: 'struct std::pair<const std::basic_string<char>, std::vector<std::basic_string<char> > >' has no member named 'begin' for(auto SubIterator = Iterator->begin(); SubIterator != Iterator->end(); SubIterator++) ^ Lexer.cpp:29:76: error: 'struct std::pair<const std::basic_string<char>, std::vector<std::basic_string<char> > >' has no member named 'end' for(auto SubIterator = Iterator->begin(); SubIterator != Iterator->end(); SubIterator++) ^
How can a set a pointer , to a matrix example matrix[20][20] and iterate ( loop ) in each row first sort of X first and then Y through it using the pointer , how to setup dynamic allocation
through pointer = new matrix[20][20]
and finally call delete on pointer when done with the matrix.
I need to allow the user to input an integer of any length and print out the word of each number in the integer. So the user would enter "324562" and then the output would be "three two four five six two". I'm struggling to understand the best way to do it in C. I know I need a loop that goes through the int but I don't know how to do it
I need to iterate through a vector in a const function, and, as my function is called very often, to get more performances I need my iterator to be declared somewhere else than the function, so it doesn't have to get deleted and recreated over and over again. So here is my code:
A C++ container type called std::map is used to store elements that are formed by a combination of key value and mapped value. How do you iterate through this container and find the value mapped to a specific key?
The example enable a client to iterate the internal std::vector using being() and end().
Code: class foo { public: typedef std::vector<std::string>const_iterator iter; iter begin () const; iter end () const;
[Code] .....
In the future I see the need for this class to be able to control sequence (sorting) and also show a subset of the complete list based on a search parameter.
Using std::sort appear to solve the ability to sort the collection.
How can I return an iterator to the client which only iterates a sub-set of all items in the std::vector?
An example would be, I add this method to the class;
Code: void find(const std::string& st);
So if the client performs (below) only items in std::vector that contains the character "a" should be possible to iterate.
Code: foo f; f.search("a");
One option would be to operate with two collection inside the foo class. One more static containing all items and the other containing the sorted and filtered items. This would lead to some copying but should work. Far from perfect.
I need to use dynamic memory allocation and use pointers to iterate through the arrays that I have already in this program. I am lost, nothing I do works and where to use the pointers. I am just looking for a push in the right direction so I can finish this project and how I can implement pointers in my program.
So I have an issue with a homework assignment that I am coding. I am attempting to get a function to iterate through an array and search for a number that was stored in an array by the user. So far I can take the number, get the numbers displayed but in my menuChoice2 function, for some reason the program is not confirming whether or not the number is entered, and is only telling me that the number has not been found, instead of confirming that the number is in the array.
Here is my code thusfar:
#include <stdio.h> #include <stdlib.h> #include <stdbool.h> // Variables that are Globally declared int menuChoice = 0; int usernum[1000] = { ' ' };
[Code] .....
To be clear I am not getting any errors but something is telling me that the error is in the formatting of menuChoice2.
I am trying to iterate a matrix in order to exchange rows and columns element by element. Although the function that exchanges the rows has come out well, i don't seem to figure out how to do the same on columns.The columns switch for a matrix like
I am trying to write a loop that will iterate through a char array in C and pull the IP addresses and test them to see if they respond. My ultimate goal is to have the first one that responds returned in the function, but the loop is not running correctly. It will run through right the first time, but then will start over again.
Code output: Contents of srList b4 loop: 1.1.1.1 Server List: 1.1.1.1 result is "1.1.1.1" Hitting else loop Contents of srList in else: 2.2.2.2 result is "2.2.2.2" result is "2.2.2.2" Contents of srList b4 loop: 1.1.1.1 Server List: 1.1.1.1 result is "1.1.1.1" Hitting else loop Contents of srList in else: (null)
I am very much a beginner at C and a large amount of it still tends to go over my head, I've created a 2d array which its size is generated from user input and filled with random integers. Next I need to locate the maximum and minimum figures in the integer and as dull..This is the code I have so far
Code:
#include <stdio.h>#include <stdlib.h> int main () { int firstDimension, secondDimension, firstDimensionIndex, secondDimensionIndex,index; int **table; }
I am making a game and I am attempting to get the zombies to move randomly but for the life of me, I simply don't have the knowledge with srand to do it
I can't get the sum of two randomly generated numbers - I don't believe the program is adding wrong what I think might be happening is upon hitting enter its adding two new randomly generated numbers -
Code: // Program functions as a math tutor #include <cstdlib> #include <iostream> #include <ctime> using namespace std; int main() { // Constants const int Min_Value = 1;
I want to create a randomly ordered array of integers where there are no duplicates. Is there a way of doing this in one iteration? Or maybe even a standard function for this?
I'm looking for something like this: A2 = [3 2 1 6 7 8 4 5]
I want to create a word game using c. My question is it possible to set questions and the system will randomly display each? If yes, what's the right code?
The program is supposed to be printing 21 different numbers that are randomly generated. Why am I getting the same number 21 times? Using dev C++ compiler.
Code:
/*prints random numbers between 1 - 99*/ #include <stdio.h> #include <stdlib.h> #include <time.h>
Is there any way to generate random types I build? I know rand command returns random integers, but I want to create some classes and and a function that will generate randomly 3 objects of the types I have created.
