A pointer is a variable whose value is the address of another variable, i.e., direct address of the memory location. Like any variable or constant, a pointer must be declare before storing any variable address. The general form of a pointer variable declaration is:
Syntax:
type *var_name;
Here, type is the pointers base type. It must be a valid C/C++ data type and var-name is the name of the pointer variable. The asterisk * is being used to designate a variable as a pointer. Following are the valid pointer declaration for their respective data type:
int *ip; float *fp; double *dp; char *cp;
In this article, the focus is to differentiate int* p() and int (*p)().
int* p(): Here “p” is a function that has no arguments and returns an integer pointer.
int* p() returntype function_name (arguments)
Below is the program to illustrate the use of int* p():
// C++ program to demonstrate the use // of int* p() #include <bits/stdc++.h> using namespace std;
// Function that returns integer pointer // and no arguments int * p()
{ int a = 6, b = 3;
int c = a + b;
int * t = &c;
return t;
} // Driver Code int main()
{ // Declare pointer a
int * a = p();
cout << *a;
} |
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int (*p)(): Here “p” is a function pointer which can store the address of a function taking no arguments and returning an integer. *p is the function and ‘p‘ is a pointer.
Below is the program to illustrate the use of int (*p)():
// C++ program to demonstrate the use // of int* (*p)() #include <bits/stdc++.h> using namespace std;
// Function with no arguments // and return integer int gfg()
{ int a = 5, b = 9;
return a + b;
} // Driver Code int main()
{ // Declaring Function Pointer
int (*p)();
// Storing the address of
// function gfg in function
// pointer
p = gfg;
// Invoking function using
// function pointer
cout << p() << endl;
} |
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