C Programming - Const - Discussion

Discussion Forum : Const - Find Output of Program (Q.No. 4)

Const

What will be the output of the program?

#include<stdio.h>

int main()
{
    const int x=5;
    const int *ptrx;
    ptrx = &x;
    *ptrx = 10;
    printf("%d\n", x);
    return 0;
}

Error

Garbage value

Answer: Option

Explanation:

Step 1: const int x=5; The constant variable x is declared as an integer data type and initialized with value '5'.

Step 2: const int *ptrx; The constant variable ptrx is declared as an integer pointer.

Step 3: ptrx = &x; The address of the constant variable x is assigned to integer pointer variable ptrx.

Step 4: *ptrx = 10; Here we are indirectly trying to change the value of the constant vaiable x. This will result in an error.

To change the value of const variable x we have to use *(int *)&x = 10;

Discussion:

18 comments Page 2 of 2.

Hari said: 1 decade ago

I also don't think step 4 willl work how can it will try to change the value of x answer is 5.

Rishi said: 9 years ago

What is const int x=5;int *ptrx;?

Please explain.

Prudhvi said: 1 decade ago

Any one give me a clear explanation to step 4.

Haritha said: 4 years ago

*(int *)&x = 10;

Please explain this.

Gaurav said: 8 years ago

*(int *)&x = 10;
Please explain this.

Bijay said: 1 decade ago

In gcc compiler it will work o/p:10.

Suresh said: 9 years ago

Why cannot print x values of 5?

Martyf said: 1 decade ago

It is very difficult paper.

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