I tried to clear here my logic for pointer basic
#include<iostream>
using namespace std;
int main(){
int zaki_live;
int *point_koro;
int show_koro;
zaki_live=50;
point_koro=&zaki_live;
show_koro=*point_koro;
//now printing the output
cout<<"Value of zaki_live :"<<zaki_live<<endl;
cout<<"Value of point_koro :"<<*point_koro<<endl;
cout<<"Value of show_koro_koro :"<<show_koro<<endl;
return 0;}
#include<iostream>
using namespace std;
int main(){
int var1;
int *var_show;
int var_output;
var1=20;
var_show=&var1;
var_output=*var_show;
//now printing the output
cout<<"Value of var1 :"<<var1<<endl;
cout<<"Value of *var_show :"<<var_show<<endl;
cout<<"Value of var_output :"<<var_output<<endl;
return 0;}
Actually in c++ pointer can be declare like this
type *var_name;
example:
int *ip;
double *dp;
float *fp;
char *ch;
#include<iostream>
using namespace std;
int main(){
int variable=20; //actual variable declaration
int *ip; //pointer variable
ip=&variable; //store the adddress of the variable in pointer varaibel
cout<<"value of the variable: ";
cout<<variable<<endl;
//print the address stored in pointer variable
cout<<"address stored in pointer :";
cout<<ip<<endl;
cout<<"address of the variable :";
cout<<&variable<<endl;
//access the value of the address through the pointer
cout<<"Value of ip *varibale: ";
cout<<*ip<<endl;
return 0;
}
C++ NULL Pointers
It actually represent no where
int *zaki=0;
int *dhaka=NULL;
Both the examples meaning the same attitude of the c++
It actually default by the operating systems
Here is one example:
#include<iostream>
using namespace std;
int main()
{
int *ptr=NULL;
cout<<"The value of ptr is: "<<ptr;
return 0;
}
We can also define by this
if(ptr) //it will proceed if p is not null
and
if(!ptr) //it will proceed if p is null
Pointer arithmetic
Incrementing a pointer:
#include<iostream>
using namespace std;
const int MAX=3;
int main()
{
int var[MAX]={10,100,200};
int *ptr;
ptr=var; //address of vcar in pointer ptr
for(int i=0;i<MAX;i++)
{
cout<<"Address of var["<<i<<"] = ";
cout<<ptr<<endl;
cout<<"Value of var["<<i<<"] = ";
cout<<*ptr<<endl;
ptr++;
}
return 0;
}
Decrementing a pointer:
#include<iostream>
using namespace std;
const int MAX=3;
int main()
{
int var[MAX]={10,100,200};
int *ptr;
ptr=&var[MAX-1];
for(int i=MAX;i>0;i--){
cout<<"Address of var["<<i<<"] = ";
cout<<ptr<<endl;
cout<<"Value of var["<<i<<"] = ";
cout<<*ptr<<endl;
//point to the previous location
ptr--;
}
return 0;
}
Comparison with pointer:
#include<iostream>
using namespace std;
const int MAX=3;
int main(){
int var[MAX]={10,100,200};
int *ptr;
//let us have address of the first element in pointer
ptr=var;
int i=0;
while(ptr<=&var[MAX-1]){
cout<<"Address of var["<<i<<"]: ";
cout<<ptr<<endl;
cout<<"Value of var["<<i<<"]: ";
cout<<*ptr<<endl;
//point to previous location
ptr++;
i++;
}
return 0;
}
C++ pointer vs arrays:
#include<iostream>
using namespace std;
const int MAX=3;
int main(){
int var[MAX]={10,100,200};
for(int i=0;i<MAX;i++)
{
*var=i;
cout<<var<<endl;
}
return 0;
}
C++ Array of pointers
#include<iostream>
using namespace std;
const int MAX=3;
int main(){
int var[MAX]={10,100,200};
int *ptr[MAX];
for(int i=0;i<MAX;i++){
ptr[i]=&var[i];
}
for(int i=0;i<MAX;i++)
{
cout<<"Value of var["<<i<<"] = ";
cout<<*ptr[i]<<endl;
}
return 0;
}
and also can store data like this with pointer and array mutually
#include<iostream>
using namespace std;
const int MAX=4;
int main()
{
char *names[MAX]={"Zara Ali","Mitha Ali","Sara Ali","Zaki Live"};
for(int i=0;i<MAX;i++)
{
cout<<"Value of names["<<i<<"] = ";
cout<<names[i]<<endl;
}
return 0;
}
C++ Pointer to Pointer:
#include<iostream>
using namespace std;
int main()
{
int var;
int *ptr;
int **pptr;
var=300;
ptr=&var; //take the address of teh var
pptr=&ptr;//take the address of ptr using the address operator &
//print
cout<<"Value of var: "<<var<<endl;
cout<<"Value available at *ptr: "<<*ptr<<endl;
cout<<"Value available at **pptr:"<<**pptr<<endl;
return 0;
}
