Vector or arraylist-which one is better? Why?
The answer to this question cannot be generalized. Sometimes it is better to use vector. Sometimes it is an arraylist. Sometimes neither of them is
The best choice. Don't expect a simple affirmative answer, because it depends on what you use them. Four of the following are to be considered:
Factors:
L API
L synchronous processing
L data growth
L usage mode
We wi
Label: style blog HTTP color OS Io ar Div html When setting the CPU parameters during the learning process of the nioshi II, the Reset vector and exception vector settings are encountered. Shows the parameter setting screen. Reset vector -- Reset vectorException vector -- execution VectorFirst, it indicates that both
mentioned. This is the function interval.
Description :A: Taking two-dimensional space as an example, the linear equation is changed to +c=0 ax+by+c=0.
The usage vector w instead (A, b) is represented by the feature vector x, which is the formula.B: For the straight line we learned. By substituting the negative instance point (0,0), we can see that the calculated result +1 is inconsistent with
STD: Difference Between Reserve and resize of Vector1. Reserve: Allocate space, change capacity but not size2.Resize: Allocate space. Changing the capacity also changes the size.
If you know the vector size, resize it as an array without allocating extra memory.
ReserveIt is a container reserved space, but does not actually create element objects. Before creating an object, you cannot reference the elements in the container. Therefore, when add
There is a copy function in the STL algorithm. We can easily write this code:#include #include #include using namespace STD;int_tmain (intARGC, _tchar* argv[]) {Doubledarray[Ten]={1.0,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9}; vectordouble>Vdouble (Ten); vectordouble>:: Iterator Outputiterator=vdouble.begin (); Copy (darray,darray+Ten, Outputiterator); while(Outputiterator!=vdouble.end ()) {coutreturn 0;}So you want to use copy to set the to vector, so you
Dynamically assigned vector pointer Vector If it is a dynamically allocated vector pointer, you can only use the array method (the above Code is red) when inserting elements into the vector. the push_back () function has an error. Why? Use the shared_ptr vector point
Previous blogs have written about vectors using the sort algorithm, and vector some of the processing methods that have been written before.Just write it today vector . Sort by using the sort algorithm.#include #include #include #include #include BOOLCompare_int (intAMP;LHS,int RHS) {returnLHS > RHS;}BOOLCompare_first_letter (Const STD::unique_ptrSTD::string> AMP;LHS,Const STD::unique_ptrSTD::string> RHS)
The arraylist, inclulist, and vestor classes all implement the java. util. List interface, but they have different features, mainly as follows:
I,Synchronization
Arraylist and inclulist are not synchronized, while vestor is. Therefore, if thread security is required, arraylist or javaslist can be used to save costs for synchronization. But in the case of multithreading, sometimes we have to use vector. Of course, you can also package arraylist and his
Vector series in practice c ++ -- sort the vector (unique_ptr (string) using the sort algorithm (sort function error "two parameters should be input, but three parameters are provided)
Previously, I wrote a blog post on sorting the vector using the sort algorithm.vector
>
.
Today, let's write a pairvector
>
Use the sort algorithm for sorting.
# In
In practice, the vector series in c ++ -- vector (unique_ptr () initialization (Ownership Transfer)
C ++ 11 provides us with smart pointers and brings us a lot of convenience.
What if unique_ptr is used as an element of the vector container?
The format is exactly the same:vector
> vec;
But how to add elements to vec?
See the following:
# Include
Vector initialization and traversal-dtor-blog
Vector initialization and traversal
STD: Vector
Int
>
Inttest; For(IntI=0; I10;++I){Inttest. push_back (I );} For (STD: Vector Int > : Iterator ITER = Inttest. Begin (); ITER ! = Inttest. End (); ++ ITER){STD: cout * ITER STD: Endl
For vector usage, the additional time consumed by copying data to prevent reallocate memory.
The following two combinations can be used to prevent reallocate.
1. Vector: resize () using array index
2. Vector: Reserve () Use push_back ().
So I tested these two cases on the Windows 2003 platform, and compared them with 3 in which push_back () is directly
Today we want to use vector to realize the function of two-dimensional array, and try to put the two-dimensional vector. Who knows when he got started, he met Ray.
The form of the code is roughly as follows:
VECTOR
The vacuuming operation was performed because the two-dimensional vector was reused. However, th
more and more widely valued.
Statistical Learning Theory is based on a solid set of theories and provides a unified framework for solving the problem of Finite Sample learning. It can include many existing methods and is expected to help solve many difficult problems (such as Neural Network Structure Selection and Local Minimization). At the same time, based on this theory, a new general learning method-Support Vector Machine (SVM) has been developed
In practice, the vector series in c ++ -- the second worst iterator failed (deleting elements in the vector)
Directly refer to the Code:
# Include
# Include
Using namespace std; int main () {vector
V; v. push_back (1); v. push_back (2); v. push_back (3); std: vector
: Itera
Previous blogs have talked about some of the ways to use Std::find and std::find_ if. But there is no telling of the classes stored in vectors that are defined by themselves. So how do you use Std::find and std::find_if to find it?First define a class:classitem{Private:STD::stringM_itemid;intM_price;intM_count; Public: Item (STD::stringIdintPriceintcount): M_itemid (ID), M_count (count), M_price (price) {}intGetCount ()Const{returnM_count; }STD::stringGetitemid ()Const{returnM_itemid; }intGetPri
The actual deletion element in the C + + vector uses the std::vector::erase () method in the container Vecrot.Std::remove () in C + + does not delete the element because the container's size () does not change, only the replacement of the element.1.std::vector::erase ()Function prototype: Iterator erase (iterator position); Delete the specified elementIterator Er
I write a simple program to distinguish between the vector container size () and the capacity () function, where the capacity function is to reserve space for the vector container, without having to reallocate the memory every time the element is added, thus improving the efficiency a lot. I through a small program to study, the following is the program and running results, more concise can be seen capacity
JQuery generates the svg vector QR code and jquerysvg Vector
JQuery generates a vector svg QR code and provides PNG and SVG page downloads to relieve pressure on the server.
The Code is as follows:
The above section describes how to use jQuery to generate an svg vector QR code. I hope it will be helpful to you. If you
vector Container
Vectors are a collection of objects of the same type, each with a corresponding integer index value. As with string objects, the standard library is responsible for managing the associated memory of the storage element. We refer to the vector as a container because it can contain other objects. All objects in a container must be of the same type.
Before using vectors, you must include the
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