strncpy function with two character arrays

[embeddedlover]

I have the following two code snippets:

Code 1:

char *a = "India";
char *b = "and";
strncpy(a,b,3);

Code 2:

char a[10] = "India";
char b[10] = "and";
strncpy(a,b,3);

Code snippet 2 works and snippet 1 doesn't work why?

 

[navenmou]

dude
in snippet 1 you are trying to copy the in string pointer....if you do like this the compiler will give run time error segmentation fault...once read about strings using pointers concept you will get idea....

 

[horace1]

in

char *a = "India";

"India" is a string constant and the variable a is a pointer to it. You can use ato read the characters but an attempt to write to it will cause a segmentation error.
in

char a[10] = "India";

a is an array length 10 initialised with the string "India", you can read or write the array elements.

 

[embeddedlover]

thank you, got it.... char *a defines a character pointer, pointing to character constant "India".
where as char b[10] defines an array, which can have an string assigned within it's space.
We can copy string from one array to another but not character pointer.
the way we declared matters here...

you can use ato read the characters but an attempt to write to it will cause a segmentation error.

writing is not allowed
but assigning the following way is allowed isn't?

char *a = "India";
char *b = "and";
a = b;

 

[horace1]

but assigning the following way is allowed isn't?

char *a = "India";
char *b = "and";
a = b;

yes, a and b are pointers which can hold the address of any char. You have assigned a to point to the start of string constant "and", i.e. both a and b holds the address of 'a'

you cannot do the following

char a[] = "India";
char b[] = "and";
a = b;

the identifiers a and b are constant pointers to the start of the arrays and the assignment a=b is illegal