Vector usage in C + +

Vector is a container in C + + that replaces a built-in array.

It is part of the C + + standard library.

You must include a preprocessing #include<vector> when you use it.

Vectors are used in two ways:

1. Vector<int> Vector (elem_size)

The contents of the parentheses of this method can be more than just the number of elements.

The vector cannot be initialized like an array in C.

int array[6] = {1, 2, 3, 4, 5, 6};

But you can initialize an existing array to the vector:

Vector<int> vector (array, array+6);

or initialize a portion of the array to the vector:

Vector<int> Vector (array+1, array+4);

Part of the value of the copy here is: 2,3,4 (top 3 digits, but the value of the 3 digits is somewhat strange)

Note: The values in parentheses are pointers.

Example:

1 #include <stdio.h>
2 #include <vector>
3 #include <iostream>
4 #include <string>
5

6 using namespace Std;
7
8 int Main ()
9 {
Ten int i = 0;
One vector<string> v;
//for (i = 0; i < i++) {
//V.push_back ("Wanglei");//load element into vector
14//}
string Word;
for (int i=0 i < ++i) {
CIN >> Word;
V.push_back (word);
19}
cout << "Words read are:/n";
for (Vector<string>::iterator it = V.begin (); it!= v.end (); ++it) {
cout << *it << ';
23}
cout << Endl;
25
for (i = 0; i < v.size (); i++) {
cout << V[i] << "";
28}
29
cout << Endl;
The first use of//vector: A method similar to a built-in array
const int elem_size = 10;
array[elem_size int] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
Vector<int> vector (array, array+10);
//for (int i=0 i < elem_size; ++i) {
+//Vector[i] = V[i];
37//}
for (int i=0 i < elem_size; ++i) {
cout << Vector[i];
40}
cout << Endl;
0;
43}

Compiling: $ g++ A.C

Run: $./a.out

Results:

Enter a text:
Hello world! I ' m a C + + programmer. How do I do? My name is..
Words Read are:
Hello world! I ' m a C + + programmer. How do I do?
Hello world! I ' m a C + + programmer. How do I do?
Pointers as parameters for the vector constructor:
0123456789

2. STL Usage:

Define an empty vector

vector<string> text;

The elements are then added through the push_back () function.

Example

 15     string Word;
 16     for (int i=0 i < ++i) {
 17      & nbsp;  cin >> Word;
 18         v.push_back (word);
 19    }
 20     cout << "Words read are:/n";
 21     for (Vector<string>::iterator it = V.begin (); it!= v.end (); ++it) {
 22         cout << *it << ';
 23    }
 24     cout << Endl;