1.Basics of C++

From: 

http://www.cplusplus.com/doc/tutorial/

/*

C++ Language Tutorial

1.Basics of C++
2.Control Structures
3.Compound data types
4.Object Oriented Programming
5.Advanced concepts
6.C++ Standard Library

*/

Table of contents

/*

Basics of C++
Structure of a program 
Variables and types 
Constants 
Operators 
Basic Input/Output 


Program structure
Control Structures 
Functions 
Overloads and templates 
Name visibility 


Compound data types
Arrays 
Character sequences 
Pointers 
Dynamic Memory 
Data structures 
Other data types 


Classes
Classes (I) 
Classes (II) 
Special members 
Friendship and inheritance 
Polymorphism 


Other language features
Type conversions 
Exceptions 
Preprocessor directives 


C++ Standard Library
Input/Output with files 

*/

View Code

---

1.Basics of C++

The codes:

 

// 1. Basics of C++


/***********************************
1
Structure of a program
*/

// my first program in C++
#include <iostream>
using namespace std;

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


// my second program in C++

#include <iostream>

using namespace std;

int main ()
{
  cout << "Hello World! ";
  cout << "I'm a C++ program";
  return 0;
}


/* my second program in C++
   with more comments */

#include <iostream>
using namespace std;

int main ()
{
  cout << "Hello World! ";     // prints Hello World!
  cout << "I'm a C++ program"; // prints I'm a C++ program
  return 0;
}


/***********************************
2
Variables. Data Types.
*/

// operating with variables

#include <iostream>
using namespace std;

int main ()
{
  // declaring variables:
  int a, b;
  int result;

  // process:
  a = 5;
  b = 2;
  a = a + 1;
  result = a - b;

  // print out the result:
  cout << result;

  // terminate the program:
  return 0;
}



// initialization of variables

#include <iostream>
using namespace std;

int main ()
{
  int a=5;               // initial value = 5
  int b(2);              // initial value = 2
  int result;            // initial value undetermined

  a = a + 3;
  result = a - b;
  cout << result;

  return 0;
}



// my first string
#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string mystring = "This is a string";
  cout << mystring;
  return 0;
}



// my first string
#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string mystring;
  mystring = "This is the initial string content";
  cout << mystring << endl;
  mystring = "This is a different string content";
  cout << mystring << endl;
  return 0;
}


/*********************************
3
Constants
*/

// test escape codes

#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string s;
  s="one\ntwo\nthree\n";
  cout << s;
  s="string expressed in \
two lines";
  cout << s << endl;
  s="string expressed in \
    two lines";  //space...
  cout << s << endl;
  s="b,c want:\142\143"; //octal
  cout << s << endl;
  s="b,c want:\x62\x63"; //hexadecimal
  cout << s << endl;  
  return 0;
}


// defined constants: calculate circumference

#include <iostream>
using namespace std;

#define PI 3.14159
#define NEWLINE '\n'

int main ()
{
  double r=5.0;     // radius
  double circle;

  circle = 2 * PI * r;
  cout << circle;
  cout << NEWLINE;

  return 0;
}

// test constants
#include <iostream>
using namespace std;

#define PI 3.14
const n=10;

int main ()
{
  PI=3.14159; //error 
  n=100; //error

  return 0;
}


/******************************************
4
Operators
*/

// assignment operator

#include <iostream>
using namespace std;

int main ()
{
  int a, b;         // a:?,  b:?
  a = 10;           // a:10, b:?
  b = 4;            // a:10, b:4
  a = b;            // a:4,  b:4
  b = 7;            // a:4,  b:7

  cout << "a:";
  cout << a;
  cout << " b:";
  cout << b;

  return 0;
}


// test rvalue

#include <iostream>
using namespace std;

int main ()
{
  int a, b;
  a=2+(b=5);
  cout<<a<<" "<<b<<endl;
  a=b=a;
  cout<<a<<" "<<b<<endl;

  return 0;
}



// compound assignment operators

#include <iostream>
using namespace std;

int main ()
{
  int a, b=3;
  a = b;
  a+=2;             // equivalent to a=a+2
  cout << a;
  return 0;
}


// more...
#include <iostream>
using namespace std;

int main ()
{
  int a, b=3;
  a = b;
  a+=2; //5
  cout << a << endl;
  a-=2; //3
  cout << a << endl;
  a*=2; //6
  cout << a << endl;
  a/=3; //2;
  cout << a << endl;
  a%=b; // 2 mod 3=2
  cout << a << endl;
  a>>=1; // shift right 1, 10->1
  cout << a << endl;
  a<<=3; // shift left 3, 1->1000
  cout << a << endl;
  a&=15; // 1000 and 1111 -> 1000
  cout << a << endl;
  a^=15; // 1000 xor 1111 -> 0111
  cout << a << endl;
  a|=15; // 0111 or 1111 -> 1111
  cout << a << endl;  
  
  return 0;
}

// difference of: ++a a++
#include <iostream>
using namespace std;

int main ()
{
  int a, b=3;
  a=++b; // increased befor...
  cout << a << endl;
  b=3;
  a=b++; // include after...
  cout << a << endl;
  
  return 0;
}



// conditional operator
#include <iostream>
using namespace std;

int main ()
{
  int a,b,c;
  a=2;
  b=7;
  c = (a>b) ? a : b;
  cout << c;
  return 0;
}


// comma operator
#include <iostream>
using namespace std;

int main ()
{
  int a,b,c;
  c = ( a=2, b=7, a>b?a:b ); //
  cout << c;
  return 0;
}


// type casting operator
#include <iostream>
using namespace std;

int main ()
{
  int i;
  double f=3.14;
  i=(int)f;
  cout << i << endl;
  i=int(f);
  cout << i << endl;
  i=98;
  cout << char(i) << endl; // same as pascal
  return 0;
}


/*************************************
5
Basic Input/Output
*/

// cout
#include <iostream>
using namespace std;

int main ()
{
  cout << "First sentence.\n";
  cout << "Second sentence.\nThird sentence.";
  return 0;
}


// i/o example

#include <iostream>
using namespace std;

int main ()
{
  int i;
  cout << "Please enter an integer value: ";
  cin >> i;
  cout << "The value you entered is " << i;
  cout << " and its double is " << i*2 << ".\n";
  return 0;
}


// cin with strings
#include <iostream>
#include <string>
using namespace std;

int main ()
{
  string mystr;
  cout << "What's your name? ";
  getline (cin, mystr);
  cout << "Hello " << mystr << ".\n";
  cout << "What is your favorite team? ";
  getline (cin, mystr);
  cout << "I like " << mystr << " too!\n";
  return 0;
}



// stringstreams
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

int main ()
{
  string mystr;
  float price=0;
  int quantity=0;

  cout << "Enter price: ";
  getline (cin,mystr);
  stringstream(mystr) >> price; //convert strings to numerical values 
  cout << "Enter quantity: ";
  getline (cin,mystr);
  stringstream(mystr) >> quantity;
  cout << "Total price: " << price*quantity << endl;
  return 0;
}



// more
#include <iostream>
#include <string>
using namespace std;

int main ()
{
  int i,j;
  char c;
  cin>>i>>j;
  cin>>c;
  cout<<i<<" "<<j<<endl;
  cout<<c<<endl;
  return 0;
}
// cin always uses blank space character?

 

 

 

 

 

 

 

 

 

TOP

 

 

 

 

 

 

转载于:https://www.cnblogs.com/xin-le/p/4083900.html