в 14:21, 25 мая 2010

2010-05-25T14:21:17Z

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2010-05-25T10:29:49Z

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==arguments passed by pointer==

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

int main(){
void centimize(double*);

double var = 10.0;
cout << "var = " << var << " inches" << endl;

centimize(&var);
cout << "var = " << var << " centimeters" << endl;
return 0;
}
void centimize(double* ptrd){
*ptrd *= 2.54;
}</source>

==arguments passed by reference==

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

int main(){
void centimize(double&);

double var = 10.0;
cout << "var = " << var << " inches" << endl;

centimize(var);
cout << "var = " << var << " centimeters" << endl;
return 0;
}
void centimize(double& v){
v *= 2.54;
}</source>

==array passed by pointer==

<source lang="cpp">#include <iostream>
using namespace std;
const int MAX = 5;

int main(){
void centimize(double*);

double varray[MAX] = { 10.0, 43.1, 95.9, 59.7, 87.3 };

centimize(varray);

for(int j=0; j<MAX; j++)
cout << "varray[" << j << "]=" << varray[j] << " centimeters" << endl;
return 0;
}
void centimize(double* ptrd){
for(int j=0; j<MAX; j++)
*ptrd++ *= 2.54;
}</source>

==Arrays of pointers to functions==

<source lang="cpp">#include <iostream>

void Square (int&,int&);
void Cube (int&, int&);
void Swap (int&, int &);
void GetVals(int&, int&);
void PrintVals(int, int);

int main()
{
int valOne=1, valTwo=2;
int i;
const int MaxArray = 5;
void (*pFuncArray[MaxArray])(int&, int&);

pFuncArray[0] = GetVals;
pFuncArray[1] = Square;
pFuncArray[2] = Cube;
pFuncArray[3] = Swap;
pFuncArray[4] = Square;

for (i=0;i<MaxArray; i++)
{
pFuncArray[i](valOne,valTwo);
PrintVals(valOne,valTwo);
}
return 0;
}

void PrintVals(int x, int y)
{
std::cout << "x: " << x << " y: " << y << std::endl;
}

void Square (int & rX, int & rY)
{
rX *= rX;
rY *= rY;
}

void Cube (int & rX, int & rY)
{
int tmp;

tmp = rX;
rX *= rX;
rX = rX * tmp;

tmp = rY;
rY *= rY;
rY = rY * tmp;
}

void Swap(int & rX, int & rY)
{
int temp;
temp = rX;
rX = rY;
rY = temp;
}

void GetVals (int & rValOne, int & rValTwo)
{
std::cout << "New value for ValOne: ";
std::cin >> rValOne;
std::cout << "New value for ValTwo: ";
std::cin >> rValTwo;
}</source>
<pre class=codeResult>New value for ValOne: 1
New value for ValTwo: 2
x: 1 y: 2
x: 1 y: 4
x: 1 y: 64
x: 64 y: 1
x: 4096 y: 1</pre>

==Function pointer for overloaded function==

<source lang="cpp">#include <iostream>
using namespace std;
int myfunc(int a);
int myfunc(int a, int b);
int main()
{
int (*fp)(int a); // pointer to int f(int)
//int (*fp)(int a, int b);
fp = myfunc; // points to myfunc(int)
cout << fp(5);
return 0;
}
int myfunc(int a)
{
return a;
}
int myfunc(int a, int b)
{
return a*b;
}</source>
<pre class=codeResult>5"</pre>

==orders two arguments using pointers==

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

int main(){
void order(int*, int*);

int n1=99, n2=11;
int n3=22, n4=88;

order(&n1, &n2);
order(&n3, &n4);

cout << "n1=" << n1 << endl;
cout << "n2=" << n2 << endl;
cout << "n3=" << n3 << endl;
cout << "n4=" << n4 << endl;
return 0;
}
void order(int* numb1, int* numb2){
if(*numb1 > *numb2){
int temp = *numb1;
*numb1 = *numb2;
*numb2 = temp;
}
}</source>

==sorts an array using pointers==

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

int main(){
void bsort(int*, int);
const int N = 10;
int arr[N] = { 37, 84, 62, 91, 11, 65, 57, 28, 19, 49 };

bsort(arr, N);

for(int j=0; j<N; j++)
cout << arr[j] << " ";
cout << endl;
return 0;
}
void bsort(int* ptr, int n){
void order(int*, int*);
int j, k;

for(j=0; j<n-1; j++)
for(k=j+1; k<n; k++)
order(ptr+j, ptr+k);
}
void order(int* numb1, int* numb2){
if(*numb1 > *numb2){
int temp = *numb1;
*numb1 = *numb2;
*numb2 = temp;
}
}</source>

==Use function pointers as a function parameter==

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

void Square (int&,int&);
void Cube (int&, int&);
void Swap (int&, int &);
void GetVals(int&, int&);
void PrintVals(void (*)(int&, int&),int&, int&);

int main()
{
int valOne=1, valTwo=2;
void (*pFunc)(int&, int&);

pFunc = GetVals;
PrintVals ( pFunc, valOne, valTwo);
pFunc = Square;
PrintVals ( pFunc, valOne, valTwo);
pFunc = Cube;
PrintVals ( pFunc, valOne, valTwo);
pFunc = Swap;
PrintVals ( pFunc, valOne, valTwo);

return 0;
}

void PrintVals( void (*pFunc)(int&, int&),int& x, int& y)
{
cout << "x: " << x << " y: " << y << endl;
pFunc(x,y);
cout << "x: " << x << " y: " << y << endl;
}

void Square (int & rX, int & rY)
{
rX *= rX;
rY *= rY;
}

void Cube (int & rX, int & rY)
{
int tmp;

tmp = rX;
rX *= rX;
rX = rX * tmp;

tmp = rY;
rY *= rY;
rY = rY * tmp;
}

void Swap(int & rX, int & rY)
{
int temp;
temp = rX;
rX = rY;
rY = temp;
}

void GetVals (int & rValOne, int & rValTwo)
{
cout << "New value for ValOne: ";
cin >> rValOne;
cout << "New value for ValTwo: ";
cin >> rValTwo;
}</source>
<pre class=codeResult>x: 1 y: 2
New value for ValOne: 1
New value for ValTwo: 2
x: 1 y: 2
x: 1 y: 2
x: 1 y: 4
x: 1 y: 4
x: 1 y: 64
x: 1 y: 64
x: 64 y: 1</pre>

==Use typedef to define a function type for function pointer==

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

void Square (int&,int&);
void Cube (int&, int&);
void Swap (int&, int &);
void GetVals(int&, int&);

typedef void (*VPF) (int&, int&) ;
void PrintVals(VPF,int&, int&);

int main()
{
int valOne=1, valTwo=2;
VPF pFunc;

pFunc = GetVals;
pFunc = Square;
pFunc = Cube;

pFunc = Swap;

PrintVals ( pFunc, valOne, valTwo);
return 0;
}

void PrintVals( VPF pFunc,int& x, int& y)
{
cout << "x: " << x << " y: " << y << endl;
pFunc(x,y);
cout << "x: " << x << " y: " << y << endl;
}

void Square (int & rX, int & rY)
{
rX *= rX;
rY *= rY;
}

void Cube (int & rX, int & rY)
{
int tmp;

tmp = rX;
rX *= rX;
rX = rX * tmp;

tmp = rY;
rY *= rY;
rY = rY * tmp;
}

void Swap(int & rX, int & rY)
{
int temp;
temp = rX;
rX = rY;
rY = temp;
}

void GetVals (int & rValOne, int & rValTwo)
{
cout << "New value for ValOne: ";
cin >> rValOne;
cout << "New value for ValTwo: ";
cin >> rValTwo;
}</source>
<pre class=codeResult>x: 1 y: 2
x: 2 y: 1</pre>

==Using function pointers==

<source lang="cpp">#include <iostream>

void Square (int&,int&);
void Cube (int&, int&);
void Swap (int&, int &);
void PrintVals(int, int);

int main()
{
void (* pFunc) (int &, int &);
int valOne=1, valTwo=2;
PrintVals(valOne, valTwo);
pFunc(valOne, valTwo);
PrintVals(valOne, valTwo);
pFunc = Square;
PrintVals(valOne, valTwo);
pFunc(valOne, valTwo);
PrintVals(valOne, valTwo);
pFunc = Cube;
PrintVals(valOne, valTwo);
pFunc(valOne, valTwo);
PrintVals(valOne, valTwo);
pFunc = Swap;
PrintVals(valOne, valTwo);
pFunc(valOne, valTwo);
PrintVals(valOne, valTwo);

return 0;
}

void PrintVals(int x, int y)
{
std::cout << "x: " << x << " y: " << y << std::endl;
}

void Square (int & rX, int & rY)
{
rX *= rX;
rY *= rY;
}

void Cube (int & rX, int & rY)
{
int tmp;

tmp = rX;
rX *= rX;
rX = rX * tmp;

tmp = rY;
rY *= rY;
rY = rY * tmp;
}

void Swap(int & rX, int & rY)
{
int temp;
temp = rX;
rX = rY;
rY = temp;
}</source>
<pre class=codeResult>x: 1 y: 2</pre>

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