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2010-05-25T14:21:06Z

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2010-05-25T10:27:23Z

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==Demonstrates the use of return values with reference type.==

<source lang="cpp">
#include <iostream>
#include <string>
using namespace std;

double& referenceMin( double&, double&);

int main()
{
double x1 = 3.1, x2 = x1 + 10.5, y;
y = referenceMin( x1, x2);
cout << "x1 = " << x1 << " "
<< "x2 = " << x2 << endl;
cout << "Minimum: " << y << endl;
++referenceMin( x1, x2);
cout << "x1 = " << x1 << " "
<< "x2 = " << x2 << endl;
++referenceMin( x1, x2);

cout << "x1 = " << x1 << " "
<< "x2 = " << x2 << endl;
referenceMin( x1, x2) = 10.1;

cout << "x1 = " << x1 << " "
<< "x2 = " << x2 << endl;
referenceMin( x1, x2) += 5.0;
cout << "x1 = " << x1 << " "
<< "x2 = " << x2 << endl;
return 0;
}
double& referenceMin( double& a, double& b){
return a <= b ? a : b;
}

</source>

==Expressions with reference type exemplified by string assignments.==

<source lang="cpp">
#include <iostream>
#include <string>
#include <cctype>
using namespace std;
void strToUpper( string& );
int main(){
string text("Test with assignments \n");
strToUpper(text);
cout << text << endl;
strToUpper( text = "lower case");
cout << text << endl;
strToUpper( text += " and lower case!\n");
cout << text << endl;
return 0;
}
void strToUpper( string& str){
int len = str.length();
for( int i=0; i < len; ++i)
str[i] = toupper( str[i]);
}

</source>

==Function parameters==

<source lang="cpp">
#include <iostream>
#include <string>
using namespace std;
void printMessage(string, int);
int main ()
{
string name;
int age;
cout << "Enter name: ";
cin >> name;
cout << "Enter age: ";
cin >> age;
printMessage(name, age);
return 0;
}
void printMessage (string theName, int theAge)
{
cout << "Your name is " << theName
<< " and your age is " << theAge << endl;
}

</source>

==Function: reference version and pointer version==

<source lang="cpp">
#include <iostream>
using namespace std;
void referenceVersion(int &i); // reference version
void pointerVersion(int *i); // pointer version
int main()
{
int i = 10;
int j = 20;
referenceVersion(i);
pointerVersion(&j);
cout << i << " " << j << "\n";
return 0;
}
// using a reference parameter
void referenceVersion(int &i)
{
i = -i;
}
// using a pointer parameter
void pointerVersion(int *i)
{
*i = - *i;
}

</source>

==Function uses two arguments==

<source lang="cpp">
#include <iostream>
#include <string>
using namespace std;
void printMessage(string, string);
int main ()
{
string name1, name2;
cout << "Enter first name: ";
cin >> name1;
cout << "Enter last name: ";
cin >> name2;
printMessage(name1, name2);
return 0;
}
void printMessage (string firstName, string lastName)
{
cout << "Your name is " << firstName << " " << lastName << endl;
}

</source>

==Passed by value and passed by reference==

<source lang="cpp">
#include <iostream>
using namespace std;
void addNumbers(int, int, int&);
int main ()
{
int firstNum, secondNum, sum = 0;
cout << "Enter first number: ";
cin >> firstNum;
cout << "Enter second number: ";
cin >> secondNum;
addNumbers (firstNum, secondNum, sum);
cout << firstNum << " + " << secondNum << " = " << sum;
return 0;
}
void addNumbers (int x, int y, int& z)
{
z = x + y;
}

</source>

==Passes the variable to be doubled by reference==

<source lang="cpp">
#include <iostream>
using namespace std;
void doubleIt(int&);
int main ()
{
int num;
cout << "Enter number: ";
cin >> num;
doubleIt(num);
cout << "The number doubled in main is " << num << endl;
return 0;
}

void doubleIt (int& x)
{
cout << "The number to be doubled is " << x << endl;
x *= 2;
cout << "The number doubled in doubleIt is " << x << endl;
}

</source>

==Passing Arguments by Reference==

<source lang="cpp">
#include <iostream>
using namespace std;
void doubleIt(int);
int main ()
{
int num;
cout << "Enter number: ";
cin >> num;
doubleIt(num);
cout << "The number doubled in main is " << num << endl;
return 0;
}
void doubleIt (int x)
{
cout << "The number to be doubled is " << x << endl;
x *= 2;
cout << "The number doubled in doubleIt is " << x << endl;
}

</source>

==Passing Arguments by Value==

<source lang="cpp">
#include <iostream>
#include <string>
using namespace std;
void printMessage(string);
int main ()
{
string str;
cout << "Enter a string: ";
cin >> str;
printMessage(str);
return 0;
}
void printMessage (string s)
{
cout << "You inputted " << s;
}

</source>

==Pass string (char *) into a function==

<source lang="cpp">
#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
void center(char *s);
int main()
{
center("www.java2s.com");
center("www.java2s.com");
return 0;
}
void center(char *s)
{
int len;
len = 40+(strlen(s)/2);
cout << setw(len) << s << "\n";
}

</source>

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