C Programming - Const - Discussion

Discussion Forum : Const - Find Output of Program (Q.No. 3)
What will be the output of the program?
int fun(int **ptr);

int main()
    int i=10;
    const int *ptr = &i;
    return 0;
int fun(int **ptr)
    int j = 223;
    int *temp = &j;
    printf("Before changing ptr = %5x\n", *ptr);
    const *ptr = temp;
    printf("After changing ptr = %5x\n", *ptr);
    return 0;
Address of i
Address of j
Error: cannot convert parameter 1 from 'const int **' to 'int **'
Garbage value
Answer: Option
No answer description is available. Let's discuss.
23 comments Page 1 of 3.

Rajlaxmi said:   2 years ago
const int *ptr = &i; This is a pointer to the constant integer, where the integer is stored in RODATA.(We can't modify the value pointed by ptr anymore through ptr i.e. *ptr = ; is not allowed further).

int fun(int **ptr)

Here ptr is a double pointer to an integer. As fun is a different function new stack frame will be initialized for fun().

*ptr = temp;
Overriding the value inside the function is local to the fun and *ptr is within the newly initialized stack frame for fun. So this won't throw any errors.

const *ptr = temp;
As we already have a declaration for this as int **, this leads to a compilation error.
The analysis is according to GCC compiler.

Kareena said:   3 years ago
Hello everyone.

int i=10;
const int *ptr = &i;

Here, ptr is a pointer to a constant integer.
And therefore it should point to a constant integer.
But ptr is pointing to i, which is not a constant integer.

It should be like this:

const int i=10;
const int *ptr = &i;

TDas said:   3 years ago
Const *ptr=temp; here *ptr is already a constant pointer which is holding the address of i. Therefore,it can not be reinitialized with another pointer variable temp which is holding the address of j.

Ramana said:   4 years ago
In the function defination **ptr is integer type and it is redeclared as const int *. So it will come error as ptr is redeclared as different kind of symbol.

Prathyusha said:   6 years ago
In my ubuntu os, error: \'ptr\' redeclared as different kind of symbol
puzzle4.c:11:15: note: previous definition of \'ptr\' was here
int fun(int **ptr)

Can anyone help me to solve this?

Babu said:   6 years ago
What is the meaning of %5x ? what type of format specifier is this?

Uma said:   6 years ago
Can anyone tell what does this **ptr here?

Does this tell the address of address?

Kavya said:   7 years ago
How to rectify the error? Anyone help me.

Siva said:   7 years ago
Can anyone explain to me?

How will the result come ptr=29ff0c ptr=29fed8?

Arshita said:   7 years ago
How will the result come as ptr=29ff0c ptr=29fed8 how it comes?

Can anyone explain me?

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