C Language Doubt Point

Const

The compiler typically does not allocate memory for normal const, but instead saves them in the symbol table.

This makes it a constant during compilation, with no storage and read operations, making it highly efficient

const INT * Const P4 = &a;

const INT * P4 = &a;

int * Const P4 = &a;

Memory skills look at the position of *

If the const on the left side of the * indicates that the value cannot be changed, but pointing can change

If const on the right side of the * indicates that the point cannot be changed, but the value can be changed

If on * But both sides there is a const identity point and the value cannot be changed

5) malloc function:

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

The first address of the newly requested memory space is stored in P

If you do not assign a value to a malloc application, the amount of garbage stored is

int *p = (int *) malloc (4 * sizeof (int));//16 bytes

Calloc: Allocating memory space for the specified number of blocks and lengths

Format: calloc (number of blocks, length)

Allocated 4 pieces of memory with 4 bytes each

Their addresses are also contiguous and can be automatically initialized to 0.

int *P1 = (int *) calloc (4, sizeof (int));

Relloc can extend the size of existing memory space

return new memory space address

p = realloc (p, + * sizeof (int));

Using a function to initialize the memset, the intermediate is the ASIC code;

memset (P, ' A ', 16);

if (P! = NULL) {

*p = 10;

* (p + 1) = 100;

* (p + 2) = 1000;

}else{

printf ("Failed to request memory space!") ");

}

printf ("%p%p%p", *p, * (P + 1), * (P + 2));

return 0;

}

C Language Doubt Point