{"id":521,"date":"2013-07-26T15:22:48","date_gmt":"2013-07-26T22:22:48","guid":{"rendered":"http:\/\/192.168.1.2\/wordpress\/?p=521"},"modified":"2013-07-26T17:01:34","modified_gmt":"2013-07-27T00:01:34","slug":"c-pointer","status":"publish","type":"post","link":"http:\/\/cywang.no-ip.org\/wordpress\/?p=521","title":{"rendered":"C Pointer"},"content":{"rendered":"

\n\tPointer Related: Array, Structure, Single Pointer (*), Double Pointer (**), Reference (&)\n<\/p>\n

\n\t\n<\/p>\n

\n\t1-D Array: integer<\/span>\n<\/p>\n

\r\nint a[5] = {10,20,30,40,50};<\/pre>\n
\n\tOutput\n<\/p>\n
\n\ta[0] = 10      &a[0] = 0x5FBFF8E0      a + 0 = 0x5FBFF8E0
\n\ta[1] = 20      &a[1] = 0x5FBFF8E4      a + 1 = 0x5FBFF8E4
\n\ta[2] = 30      &a[2] = 0x5FBFF8E8      a + 2 = 0x5FBFF8E8
\n\ta[3] = 40      &a[3] = 0x5FBFF8EC      a + 3 = 0x5FBFF8EC
\n\ta[4] = 50      &a[4] = 0x5FBFF8F0      a + 4 = 0x5FBFF8F0\n<\/p>\n
\n\t\u200b\"1D_Array\"<\/a>\n<\/p>\n
\n\t2-D Array: integer<\/span>\n<\/p>\n
\r\nint a[3][2] = {10,20,30,40,50,60};\r\n\/\/ or\r\nint a[3][2] = { {10,20},{30,40},{50,60}};\r\n\/\/ or\r\nint **a; \r\n\/*\r\n    **a = 10, *(*a+1) = 20\r\n    **(a+1) = 30, *(*(a+1)+1) = 40\r\n*\/\r\n<\/pre>\n
\n\ta[x][y] = *(a[x] + y) = *( *(a+x) + y )<\/span>\n<\/p>\n
\n\tOutput\n<\/p>\n
\n\ta[0][0] = 10      a[0] + 0 = 0x5FBFF8E0   ;   a[0][1] = 20      a[0] + 1 = 0x5FBFF8E4 
\n\ta[1][0] = 30      a[1] + 0 = 0x5FBFF8E8   ;   a[1][1] = 40      a[1] + 1 = 0x5FBFF8EC 
\n\ta[2][0] = 50      a[2] + 0 = 0x5FBFF8F0   ;   a[2][1] = 60      a[2] + 1 = 0x5FBFF8F4 
\n\ta[0] = 0x5FBFF8E0      a + 0 = 0x5FBFF8E0      *(a+0) = 0x5FBFF8E0
\n\ta[1] = 0x5FBFF8E8      a + 1 = 0x5FBFF8E8      *(a+1) = 0x5FBFF8E8
\n\ta[2] = 0x5FBFF8F0      a + 2 = 0x5FBFF8F0      *(a+2) = 0x5FBFF8F0\n<\/p>\n
\n\t\"2D_Array\"<\/a>\n<\/p>\n
\n\tchar * vs. char []<\/span>\n<\/p>\n
\r\nchar ch1[] = "abcde";\r\nprintf("0x%X 0x%X \\t %s\\n",ch1,&ch1,ch1);\r\n    \r\nchar *ch2 = "abcde";\r\nprintf("0x%X 0x%X \\t %s\\n",ch2,&ch2,ch2);<\/pre>\n
\n\tOutput\n<\/p>\n
\n\tch1(%X) = 0x5FBFF8F2   &ch1 = 0x5FBFF8F2      ch1(%s) = abcde
\n\tch2(%X)<\/span> = 0xE37            &ch2 = 0x5FBFF8F0      ch2(%s) = <\/span>abcde\n<\/p>\n
\n\t\"char<\/a>\n<\/p>\n
\n\t \n<\/p>\n
\n\tStructure\n<\/p>\n
\r\nstruct student\r\n{\r\n    char firstname[20];\r\n    char *lastname;\r\n    int score;\r\n};\r\nstruct student s1 = {"Carlos", "Wang", 100};\r\nprintf("%s %s = %d\\n",s1.firstname,s1.lastname,s1.score);\r\nprintf("&s1 = 0x%X\\n",&s1);\r\n\r\nprintf("&s1.firstname = 0x%X \\t s1.firstname(%%X) = 0x%X \\t s1.firstname(%%s) = %s\\n",&s1.firstname,s1.firstname, s1.firstname);\r\n\r\nprintf("&s1.lastname = 0x%X \\t s1.lastname(%%X) = 0x%X \\t s1.lastname(%%s) = %s\\n",&s1.lastname,s1.lastname, s1.lastname);\r\n<\/pre>\n
\n\tOutput\n<\/p>\n
\n\tCarlos Wang = 100
\n\t&s1 = 0x5FBFF8D0
\n\t&s1.firstname = 0x5FBFF8D0      s1.firstname(%X) = 0x5FBFF8D0      s1.firstname(%s) = Carlos
\n\t&s1.lastname = 0x5FBFF8E8      s1.lastname(%X) = 0xE1D      s1.lastname(%s) = Wang\n<\/p>\n
\n\t \n<\/p>\n
\n\t <\/p>\n","protected":false},"excerpt":{"rendered":"
Pointer Related: Array, Structure, Single Pointer (*), Double Pointer (**), Reference (&)<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[7],"tags":[],"class_list":["post-521","post","type-post","status-publish","format-standard","hentry","category-cc"],"_links":{"self":[{"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/521","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=521"}],"version-history":[{"count":14,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/521\/revisions"}],"predecessor-version":[{"id":526,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/521\/revisions\/526"}],"wp:attachment":[{"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=521"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=521"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/cywang.no-ip.org\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=521"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}