dataseg.c

C源码集

#include <stdio.h>

int main ()
{
	char *PtoString = "The boy stood on the burning deck\n";

	/* the string is sored in the data segment.
	   PtoString holds the address of its first character */

	"I wandered lonely as a cloud\n";

	/* this also puts a string into the data segment, but we
	 don't provide a variable to store the address so don't
	 know how to get at it!

	 Some compilers recognise this and decide not to store
	 the string at all */

	 printf("Humpty Dumpty sat on a wall\n");

	 /* another string for the data segment. There's no
	    variable to store the address but the address is
	    passed to printf so printf can print the characters
		 stored at successive locations until it meets a '\0' */

	 printf("%s", PtoString);

	 /* yes, even this writes to the data segment! it stores three
		 characters - %, s and the null \0. The address of the first
		 character, the %, is passed to printf which encounters the %s
		 specifier. This tell sit to take the address stored in PtoString
		 and to walk down the characters until it meets null */

	 printf(PtoString);

	 /* pass the pointer directly to printf. Rather than having to
		 go through a %s, it gets a pointer to T atthe beginning of
		 the string	 */

	 return 0;
}