malloc call

[Netadmin]

Can somebody explain to me what does (1<<20) mean in below code.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main (void) {
        int n = 0;
        char *p;

        while (1) {
                if ((p = malloc(1<<20)) == NULL) {
                        printf("malloc failure after %d MiB\n", n);
                        return 0;
                }
                memset (p, 0, (1<<20));
                printf ("got %d MiB\n", ++n);
        }
}

[\007]

It shifted the bit 20 to the left. 2^20 = 1048576 which is one MB. I guess it mallocs 1 mb of space for p. If the malloc fails then it returns NULL, which the statement also checks for.