Chapter 3 Strings, Vectors, and Arrays

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P74-P118

A string represents a variable-length sequence of characters. A vector holds a variable-length sequence of an object of a given type.

A using declaration for the namespace

using namespace:name;
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The header file should not contain a USING declaration.

Library type String

#include <string>
using namespace std;
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(1) Definition and initialization

string s1;
sting s2(s1);
string s3("value");
string s3 = "value";
string s4(n, 'c');
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(2) String operations

s.empty(); / / to empty s.s considering (); // number of characters s[n]; // reference s1+s2 to the NTH character in s; // s1 and S2 connect <,<=,>,>= // compareCopy the code

::: warning

The Standards bureau allows literal and string literals to be converted to string objects. Literals and strings are different types.

: : :

(3) Handle characters in string objects

::: tip C++ program headers should use cname instead of name.h :::

Iterate over each value in a given sequence to perform some kind of operation

for (declaration : expression)
    statement
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The library type vector

A library vector represents a collection of objects, all of which are of the same type.

Vector is a class template, not a type.

(1) Define and initialize vector

vector<T> v1;
vector<T> v2(v1);
vector<T> v2 = v1;
vector<T> v3(n, val);
vector<T> v4(n); vector<T> v5{a,b,c... } vecrot<T> v5={a,b,c... }Copy the code

If parentheses are used, the supplied values are used to construct a vector.

If we use curly braces, we initialize the vector with a list.

(2) Add elements to vector

Start by defining an empty vector to which push_back is used at run time.

(3) Other vector operations

v.empty(a); v.size(a); v.push_back(t);
v[n];
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::: warning

Subscripts can only be performed on elements that are confirmed to exist.

: : :

Introduction to iterators

Iterator operator

*iter            // Dereference, return reference
iter->mem        // equivalent to (*iter).mem++iter --iter iter1 == iter2 iter1 ! = iter2 iter + n iter - n iter += n iter -= n iter1 - iter2// The result of subtracting two iterators is the distance between them>, > =, <, < =// Position comparison
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::: warning

Any loop body that uses an iterator cannot add elements to the container to which the iterator belongs.

: : :

An array of

(1) Array, pointer

When we use an array subscript, we usually define it as size_t.

::: warning

Defining an array must specify the type of the array. Auto inference is not allowed.

No array of references exists.

If two Pointers point to unrelated objects, they cannot be compared.

: : :

Multidimensional array

A multidimensional array is really an array of arrays.

size_t cnt = 0;
for(auto &row : a)
	for (auto &col : row){
		col = cnt;
		++cnt;
	}
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int *ip[4];    // An array of integer Pointers
int (*ip)[4];  // Point to an array of 4 integers
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The term

Begin string and vector members that return an iterator to the first element. Also a library function that takes an array and returns a pointer to the first element of the array.

A member of the end string and vector that returns a trailing iterator. Also a library function that takes an array and returns a pointer to the next element at the end of the array.