【C++ Introduction and Basic】_initializer in parenthesis-优快云博客

Becoming an expert won’t happen overnight, but with a little patience, you’ll get there.

Programming Languages

Machine Language

Assembly Language

High-level Languages

compiler
interpreter

Most languages can be compiled or interpreted, however, traditionally languages like C, C++, and Pascal are compiled, whereas “scripting” languages like Perl and Javascripttend to be interpreted. Some languages, like Java, use a mix of the two.

C/C++

C++ (pronounced see plus plus) was developed by Bjarne Stroustrup at Bell Labs as an extension to C, starting in 1979.
C++’s claim to fame results primarily from the fact that it is an object-oriented language.
C++ was standardized in 1998 by the ISO committee .
C++ excels in situations where high performance and precise control over memory and other resources is needed.

Introduction to C++ development

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First Program

#include <iostream>

int main(){
    std::cout << "Hello World!";
    return 0;
}

> g++ .\01_test.cc -o 01_test
> .\01_test.exe

Introduction to objects and variables

Data

data is any information that can be moved, processed, or stored by a computer.

Objects and variables

In order to create a variable, we use a special kind of declaration statement called a definition .

int x; // define a variable named x, of type int

Data types

Variable assignment and initialization

assignment

#include <iostream>

int main()
{
    int width;
    width = 5; // copy assignment of value 5 into variable width

    // variable width now has value 5

    width = 7; // change value stored in variable width to 7

    // variable width now has value 7

    return 0;
}

initailization

int a; // no initializer
int b = 5; // initializer after equals sign; Copy initialization
int c( 6 ); // initializer in parenthesis; Direct initialization
int d { 7 }; // initializer in braces; Brace initialization

Introduction to iostream: cout, cin, and endl

std::endl vs ‘\n’

Using std::endl can be a bit inefficient, as it actually does two jobs:

it moves the cursor to the next line
it “flushes” the output

eg:

#include <iostream>

int main(){
    int x;
    std::cin >> x;
    std::cout << x;
    return 0;
}

cin	cout
12	12
fdffd	0
12fjlakj	12

Introduction to literals and operators

A literal (also known as a literal constant) is a fixed value that has been inserted directly into the source code.
In mathematics, an operation is a mathematical calculation involving zero or more input values (called operands) that produces a new value (called an output value).
Operators in C++ come in three different arities:
- unary
- binary
- ternary