Want to now what is the use of double pointer

[ammu]

Hi friends,

I'm new to c programming..........I need to know what is the use of double pointer and when will we use it?


Thanks
Ammu

[matsp]

Are you talking about something like this:
int **ptr;
??
The same reason as you'd have a pointer to integer vs. the integer itself.

A double pointer is simply an address of another pointer. The most common use is as an argument to a function where you need to be able to modify the pointer itself - so you need to have a pointer to the pointer, otherwise it can't be modified.

Another common case is two-dimensional arrays with dynamic sizing, in which case you'd have a pointer to a set of pointers to the actual data.

If you are asking about:
double *ptr;
then the question is "why do we need a pointer", and the above sort of explains some of that, but perhaps you would like to show us some code.

--
Mats

[Salem]

Well the first ever example you come across is this
int main ( int argc, char **argv )

[matsp]

Well the first ever example you come across is this
int main ( int argc, char **argv )

That is of course if the author didn't decide to do:

int main ( int argc, char *argv[] )

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Mats