C - assigning a value to a null pointer

Question

Hi guys I'm new to C and pointers so I hope you'll forgive me.

I have the following code:

char *str = NULL;
*str = 'a';
printf("My string is :%s\n",str);

It compiles but I'm getting a segmentation error everytime. What is the cause of this and what how can I change it so that I can assign 'a' to my string?

Thanks in advance!

Answer 1

char *str = NULL;

The pointer str is not allocated yet. So you can not dereference it. Then you tried to deference by

*str = 'a';

The segmentation fault will occur.

If you want str with "a" value, you can do this way:

char *str = "a";
printf("My string is :%s\n",str);