IndiaBIX

C Programming - Const

Exercise : Const - Point Out Errors
6.
Point out the error in the program. 
#include<stdio.h>

int main()
{
    const int k=7;
    int *const q=&k;
    printf("%d", *q);
    return 0;
}
Error: RValue required
Error: Lvalue required
Error: cannot convert from 'const int *' to 'int *const'
No error
Answer: Option
Explanation:
No error. This will produce 7 as output.
7.
Point out the error in the program. 
#include<stdio.h>
#define MAX 128

int main()
{
    char mybuf[] = "India";
    char yourbuf[] = "BIX";
    char const *ptr = mybuf;
    *ptr = 'a';
    ptr = yourbuf;
    return 0;
}
Error: cannot convert ptr const value
Error: unknown pointer conversion
No error
None of above
Answer: Option
Explanation:

Step 1: char mybuf[] = "India"; The variable mybuff is declared as an array of characters and initialized with string "India".

Step 2: char yourbuf[] = "BIX"; The variable yourbuf is declared as an array of characters and initialized with string "BIX".

Step 3: char const *ptr = mybuf; Here, ptr is a constant pointer, which points at a char.

The value at which ptr it points is a constant; it will be an error to modify the pointed character; There will not be any error to modify the pointer itself.

Step 4: *ptr = 'a'; Here, we are changing the value of ptr, this will result in the error "cannot modify a const object".

8.
Point out the error in the program. 
#include<stdio.h>
const char *fun();

int main()
{
    *fun() = 'A';
    return 0;
}
const char *fun()
{
    return "Hello";
}
Error: RValue required
Error: Lvalue required
Error: fun() returns a pointer const character which cannot be modified
No error
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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