How do strings and char arrays work in C?

Question

No guides I\'ve seen seem to explain this very well.

I mean, you can allocate memory for a char*, or write char[25] instead? What\'s the di

Answer 1

What is the difference between an allocated char* and char[25]?

The lifetime of a malloc-ed string is not limited by the scope of its declaration. In plain language, you can return malloc-ed string from a function; you cannot do the same with char[25] allocated in the automatic storage, because its memory will be reclaimed upon return from the function.

Can literals be manipulated?

String literals cannot be manipulated in place, because they are allocated in read-only storage. You need to copy them into a modifiable space, such as static, automatic, or dynamic one, in order to manipulate them. This cannot be done:

char *str = "hello";
str[0] = 'H'; // <<== WRONG! This is undefined behavior.

This will work:

char str[] = "hello";
str[0] = 'H'; // <<=== This is OK

This works too:

char *str = malloc(6);
strcpy(str, "hello");
str[0] = 'H'; // <<=== This is OK too

How do you take care of null termination of string literals?

C compiler takes care of null termination for you: all string literals have an extra character at the end, filled with \0.