A scoping example
#include <iostream>
using std::cout;
using std::endl;
void useLocal( void );
void useStaticLocal( void );
void useGlobal( void );
int x = 1;
int main()
{
int x = 5;
cout << x << endl;
{
int x = 7;
cout << "local x in main"s inner scope is " << x << endl;
}
cout << x << endl;
useLocal();
useStaticLocal();
useGlobal();
useLocal();
useStaticLocal();
useGlobal();
cout << x << endl;
return 0;
}
void useLocal( void )
{
int x = 25;
cout << "local x is " << x << " on entering useLocal" << endl;
x = x + 20;
cout << "local x is " << x << " on exiting useLocal" << endl;
}
void useStaticLocal( void )
{
static int x = 50;
cout << "local static x is " << x << " on entering useStaticLocal"
<< endl;
x = x + 20;
cout << "local static x is " << x << " on exiting useStaticLocal"
<< endl;
}
void useGlobal( void )
{
cout << "global x is " << x << " on entering useGlobal" << endl;
x = x + 20;
cout << "global x is " << x << " on exiting useGlobal" << endl;
}5
local x in main"s inner scope is 7
5
local x is 25 on entering useLocal
local x is 45 on exiting useLocal
local static x is 50 on entering useStaticLocal
local static x is 70 on exiting useStaticLocal
global x is 1 on entering useGlobal
global x is 21 on exiting useGlobal
local x is 25 on entering useLocal
local x is 45 on exiting useLocal
local static x is 70 on entering useStaticLocal
local static x is 90 on exiting useStaticLocal
global x is 21 on entering useGlobal
global x is 41 on exiting useGlobal
5
Assign value to a variable
#include <iostream>
using namespace std;
int main()
{
int length; // this declares a variable
length = 7; // this assigns 7 to length
cout << "The length is ";
cout << length; // This displays 7
return 0;
}The length is 7"
Comparing data values
#include <iostream>
using std::cin;
using std::cout;
using std::endl;
int main() {
char first = 10;
char second = 20;
cout << "The value of the expression first < second is: "
<< (first < second)
<< endl
<< "The value of the expression first == second is: "
<< (first == second)
<< endl;
return 0;
}The value of the expression first < second is: 1
The value of the expression first == second is: 0
Dynamic initialization.
#include <iostream>
using namespace std;
int main() {
double radius = 4.0, height = 5.0;
// dynamically initializ volume
double volume = 3.1416 * radius * radius * height;
cout << "Volume is " << volume;
return 0;
}Volume is 251.328"
Finding maximum and minimum values for data types
#include <limits>
#include <iostream>
using std::cout;
using std::endl;
using std::numeric_limits;
int main() {
cout << "The range for type short is from "
<< numeric_limits<short>::min()
<< " to "
<< numeric_limits<short>::max();
cout << "The range for type int is from "
<< numeric_limits<int>::min()
<< " to "
<< numeric_limits<int>::max();
cout << "The range for type long is from "
<< numeric_limits<long>::min()
<< " to "
<< numeric_limits<long>::max();
cout << "The range for type float is from "
<< numeric_limits<float>::min()
<< " to "
<< numeric_limits<float>::max();
cout << "The range for type double is from "
<< numeric_limits<double>::min()
<< " to "
<< numeric_limits<double>::max();
cout << "The range for type long double is from "
<< numeric_limits<long double>::min()
<< " to "
<< numeric_limits<long double>::max();
cout << endl;
return 0;
}The range for type short is from -32768 to 32767The range for type int is from -
2147483648 to 2147483647The range for type long is from -2147483648 to 214748364
7The range for type float is from 1.17549e-038 to 3.40282e+038The range for type
double is from 2.22507e-308 to 1.79769e+308The range for type long double is fr
om 0 to 1.#INF
Using the unary scope resolution operator
#include <iostream>
using std::cout;
using std::endl;
int n = 7;
int main()
{
double n = 10.5;
cout << "Local double value of n = " << n
<< "\nGlobal int value of n = " << ::n << endl;
return 0;
}Local double value of n = 10.5
Global int value of n = 7
