In the following rules for the case when array decays to pointer:
An lvalue [see question 2.5] of type array-of-T which appears in an expression decays (with three exceptions) into a pointer to its first element; the type of the resultant pointer is pointer-to-T.
(The exceptions are when the array is the operand of a sizeof or & operator, or is a literal string initializer for a character array.)
How to understand the case when the array is "literal string initializer for a character array"? Some example please.
Thanks!
The three exceptions where an array does not decay into a pointer are the following:
Exception 1. — When the array is the operand of sizeof
.
int main()
{
int a[10];
printf("%zu", sizeof(a)); /* prints 10 * sizeof(int) */
int* p = a;
printf("%zu", sizeof(p)); /* prints sizeof(int*) */
}
Exception 2. — When the array is the operand of the &
operator.
int main()
{
int a[10];
printf("%p", (void*)(&a)); /* prints the array's address */
int* p = a;
printf("%p", (void*)(&p)); /*prints the pointer's address */
}
Exception 3. — When the array is initialized with a literal string.
int main()
{
char a[] = "Hello world"; /* the literal string is copied into a local array which is destroyed after that array goes out of scope */
char* p = "Hello world"; /* the literal string is copied in the read-only section of memory (any attempt to modify it is an undefined behavior) */
}