C++ :: Searching STD Vector Of Strings - Counting Matching Elements And Erasing Them
Jul 19, 2013
I have read that the Erase-remove idiom is the way to go. I have a rough understanding of how this works but am unsure whether I can implement a match-counter along with it.
For counting alone, I would use something like this:
Code:
std::vector<std::string> v; // contains duplicate strings in different elements
std::string term = "foo"; // search term, changing at runtime as well
unsigned int matches = 0;
for( auto e : v ) {
if( e == term ) {
[Code] .....
I'm not sure how (or if) I can combine the two things. That is, I don't know how to integrate a function comparing two (changing) strings into the remove_if() method. Nor do I know how to increment a counter during iteration.
The vector is extremely large, so speed is paramount. I think there are many other avenues for optimization, but decreasing the vector's size for each consecutive search could deliver a big speed boost for subsequent searches I imagine, as traversing it holds the biggest cost.
I am working on a project for class where I use a parent Shape class with circle, rectangle, ect. Classes inheriting from that. Along side these I use a class called Scene. In main I need to create a scene and add some shapes to a vector in scene.
vector<Shape*> shapes
I need to use functions addShape(Shape* shape) and a delete shape method. I have the addShape finished. The problem I am having is with the delete method. Is there a way that I can use something like deleteShape(Shape* shape)? Is it possible for me to delete a specific shape from the vector by passing in that shape, or can it only be done using index? I have looked at the documentation for std::vector as well as std::vector::erase. I am wondering this because if I use index values and do something like
void Scene::deleteShape(unsigned int x) { shapes.erase(shapes.begin() + x ); }
It will lead to some errors later on due the the changing size and indexes of the vector and elements.
I am erasing a object from the vector. I want to know that do i need to delete the object before I call the erase method or calling the vector erase method is suffice. See the following example.
Class A { int val; };
Class B { vector<A *> vectorA; void AddA(int val) { A *a = new A; a->val = val; vectorA.push_back(a);
[Code] ....
I don't know which DeleteVectorEntry to use which makes sure that there is no memory leak in my program.
We are generating emails for freshman students, however, the system probably due to server overload fails to generate some emails. So I'm working on this c code( probably was a wrong choice) to search for regexp matching the generated emails and deleting from the list of students and propective emails.
I"m currently at the stage of making sure the code can find all the matching regexp from the student list file before deleting! But the code fails to read all matching regexp?
Code: //Filename: SearchReplace.c //Usage: This searches for lines in a file containing a particular work and deletes the lines. //Licence: GNU P.L. #include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h>
[code] .....
What I'm missing. It recognizes some regexp and fails to recognise some. Been staring for hours!
I do not know how to write the part indicated in Bold that represents the number of elements of contour. As seen from the code used for the tesselation OpenGL.
I want to count the elements so if the server sends a bad item id it won't crash every client in range lol. I heard that the sizeof keyword returns the size of the array in bytes. I used to think the size of keyword would return the element count but found out it isn't.
And came across the following error during link stage: "/usr/include/c++/4.6/bits/stl_vector.h:1080:4: error: no matching function for call to ‘std::vector<cv::Point_<int> >::_M_fill_initialize(std::vector<cv::Point_<int> >::size_type, int&)’ "
I need to count Words in a string in <stdio.h> and <string.h> format ONLY, must be in WHILE Loop! Our professor acts like were programming students when were just marketing students
Currently im creating a simple phone directory. I am having a problem when searching the vector. It only lets me search for the exact key in the directory when I need to to search for strings that are close to the name. For example when I search "car" it will state that its not in the directory when it should pull up Carr, Derek and Carr David.
I am trying to write a program that counts specific words that a user inputs "Howdy/howdy/Whoop/whoop" (yes I go to Texas A&M, hence those specific words) I am having an issue where it wont count the first word even if it is "Howdy"
For example if I put it:
"Howdy howdy whoop Whoop" - it only outputs that it counted 3 words
now if I were to do:
"Hello Howdy howdy whoop Whoop" - it would count 4.
Code:
#include "std_lib_facilities_4.h" int main(){ cout << "Please enter desired words, when you have entered all words, please type CTRL+d (EOF Command) " << endl; //It was assumed that EOF command was going to be used here hence the necessity of 'CTRL+d' vector<string>words;
I want to have it so that when i ask for the person witch item they want to drop on the ground it goes into another vector that i can pick back up the item if they want it back and erase when they walk away.
I'm writing a program with a class containing a private std::vector<bool>. I chose bool because the vector represents a 2D array (think grid) and I only need 2 states per cell. I kept it one-dimensional as this hardly complicates things.
My problem is that I don't know how to initialize the vector, i.e. fill it with 0's.
The grid's resolution is not known at compile time, so I imagine I have to set the size (and content) of the vector in the class constructor.
Here's what I have tried among several things:
Code: World::World(const u_short worldsize) { grid.reserve(worldsize * worldsize); // grid is the private vector; square dimensions. std::fill(grid.begin(), grid.end(), 0); std::cout << grid.size(); } The output is 0. Only std::vector::push_back seems to have an effect on size(), but judging by its description, it doesn't look like the right candidate to populate a vector with zeros. Correct me if I'm wrong.
Frankly I expected line 3 to set the vector's size.
I had a question about memory allocation/how iterators work for a std::vector<foo> of a user defined class 'foo'. Say foo contains variables of variable size, so that each member of the std::vector<foo> does not require the same amount of memory space.
Does c++ allocate the same amount of memory for each element, equal to the amount of memory required for the largest element? Or does it use some sort of array of pointers pointing to the location of each element in the vector to make the iterator work? Or does it use some other method? I am wondering because I wrote a code which reads data from a binary files and stores most of it in std::vectors.
The code seems to be using significantly more memory than the sum of the size of all the binary files, and I am using vectors made up of the datatype within the binary files (float). So I was wondering if internally the code was allocating space for each vector element which is the size of the largest element as a way to handle indexing/iterators. I ran my code through a memory leak checker and it found no errors.
I am currently trying to implement a 2d vector to store x and y of type int.
I have successfully passed it to the function, however i am unable to store the values in it. It always returns with a segmentation fault and my program terminates from there. May i know how do i store them properly and call them out?
Below is my code snippet
int reconstructSecret(int x, int y, vector< vector<int> > &inVec ,int constructSecret) { int getX,getY,formula,accum,count,getSecret,startPosition,nextPosition,numerator,denominator; getX=x; getY=y; int result;
[Code] .....
The main method
vector< vector<int> > inVec; for(int i=0;i<constructSecret;i++) { cout<<"please key in the "<<i<< "share of x value:"; cin>>x;
"Write a declaration for a function that takes two int parameters and returns an int, and declare a vector whose elements have this function pointer type."
I think std::copy appears to do what I'm looking for.
I'm in need of a vector member function that would allow me to "insert" a number of elements from one vector into another vector without resizing or destroying either.
An example of what I'm wanting to do is assign the contents of two[3-5][50-54] to one[7-9][2-6]. Other than looping through both vectors using .at(), is there a way to copy this?
This would be continuous within a user controlled loop with differing elements being exchanged.
