4 付録

4.1 型のサイズを調べる

   1 #include <stdio.h>
   2 
   3 int main(void){
   4   
   5   printf("----- size ---------\n");
   6   printf("\tchar\t%d\n", sizeof(char));
   7   printf("\tint\t%d\n", sizeof(int));
   8   printf("\tdouble\t%d\n", sizeof(double));
   9 
  10   return 0;
  11 }

----- size ---------
        char    1
        int     4
        double  8

4.2 変数のアドレスと内容を調べる

   1 #include <stdio.h>
   2 
   3 int main(void){
   4 
   5   double x=-7.696151733398438e-4;
   6   int i=55;
   7   char a='a';
   8   unsigned char *p;
   9   
  10   printf("--- char a ---------------\n");
  11   printf("%p\t%02x\n", &a, a);
  12 
  13   p=(unsigned char *)&i;
  14 
  15   printf("--- int i ----------------\n");
  16   printf("%p\t%02x\n", p, p[0]);
  17   printf("%p\t%02x\n", p+1, p[1]);
  18   printf("%p\t%02x\n", p+2, p[2]);
  19   printf("%p\t%02x\n", p+3, p[3]);
  20 
  21   p=(unsigned char *)&x;
  22 
  23   printf("--- double x -------------\n");
  24   printf("%p\t%02x\n", p, p[0]);
  25   printf("%p\t%02x\n", p+1, p[1]);
  26   printf("%p\t%02x\n", p+2, p[2]);
  27   printf("%p\t%02x\n", p+3, p[3]);
  28   printf("%p\t%02x\n", p+4, p[4]);
  29   printf("%p\t%02x\n", p+5, p[5]);
  30   printf("%p\t%02x\n", p+6, p[6]);
  31   printf("%p\t%02x\n", p+7, p[7]);
  32 
  33   return 0;
  34 }

	--- char a ---------------
	0xbffff6ab      61
	--- int i ----------------
	0xbffff6ac      37
	0xbffff6ad      00
	0xbffff6ae      00
	0xbffff6af      00
	--- double x -------------
	0xbffff6b0      00
	0xbffff6b1      00
	0xbffff6b2      00
	0xbffff6b3      00
	0xbffff6b4      00
	0xbffff6b5      38
	0xbffff6b6      49
	0xbffff6b7      bf

ホームページ: Yamamoto's laboratory
著者: 山本昌志