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C++ Pointers cookbook Cheat Sheet by

everything about pointers in c++

Array of Pointers

int *ptr[a­rra­ysize] = array of pointers, pointing to int

Pointer to function

int (*FuncPTR)(int a,int b); //called funcptr is a pointer to function
// actually is used as a parameter of another func and can pass any func to the desired func as a parameter with this method
int func1(int);
int func2(int);
int func3(int (*FuncPTR)(int));
now we can pass func1 or func2 to func3 ;

Array of Pointers to functions

void (*f[3])(int)={function1,function2,function3};
// f is an array of pointers , pointing to functions of type void which all of them take one parameter of type int .
 

Pointer vs array

int b[10]; int *bptr;
bptr=b; OR bptr=&b[0];
*(bptr+3) // shows the value of b[3]
 bptr+3 // points to &b[3] 
//an array can be used like a pointer too -> *(b+3)=value of b[3] 
//pointer to an array can be used like an array -> bptr[3] = value of b[3]

NULL pointer

int  *ptr = NULL; //The value of ptr is 0
if(ptr)     // succeeds if p is not null
if(!ptr)    // succeeds if p is null
 

passing pointers to functions

WHEN PASSING ARGUMENTS
   unsigned long sec;       
   getSeconds( &sec );
IN FUNCTION HEADER
void getSeconds(unsigned long *par)

Pointer to pointer

A pointer to a pointer is a form of multiple indirection or a chain of pointers 
   int  var;
   int  *ptr;
   int  **pptr;
   var = 3000;
   ptr = &var; // take the address of var
   pptr = &ptr;// take the address of ptr using address of operator &
 

Return pointer from functions

int * getRandom( ) {
   static int  r[10];
   return r;
}
// main function to call above defined function.
int main () {
   int *p;
   p = getRandom();
   }

Array of strings

char *color={"red","blue","yellow','green"}; 
//color is an array of pointers , pointing to the first character of each string
       
 

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