{"id":547,"date":"2009-12-25T15:35:54","date_gmt":"2009-12-25T20:35:54","guid":{"rendered":"http:\/\/vgable.com\/blog\/?p=547"},"modified":"2009-12-31T03:28:01","modified_gmt":"2009-12-31T08:28:01","slug":"a-c-puzzler","status":"publish","type":"post","link":"https:\/\/vgable.com\/blog\/2009\/12\/25\/a-c-puzzler\/","title":{"rendered":"A C &Puzzler[]"},"content":{"rendered":"

Here’s a C-puzzler for you!<\/p>\n

given this function,<\/p>\n

void foo(char* s){\n\tprintf(\"s is at: %p\\n s is: '%s'\\n\", s, s);\n}<\/pre>\n
and that<\/p>\n
\nchar s[] = \"Joy!\";\nfoo(s);\n<\/pre>\n
prints out<\/p>\n
\ns is at: 0xbffff46b<\/code>
\ns is: ‘Joy!’\n<\/p><\/blockquote>\n
what will this next line print?<\/p>\n
foo(&s); \/\/WHAT WILL THIS DO?<\/strong>\n<\/pre>\n
Pick all that apply:<\/p>\n
    \n
  1. Print “Joy!”<\/li>\n
  2. Print garbage<\/li>\n
  3. Print the same address for s<\/code><\/li>\n
  4. Print the a different address for s<\/code><\/li>\n
  5. Crash<\/li>\n
  6. Go into an Infinite loop<\/li>\n<\/ol>\n
    Answer<\/h3>\n
    Answer: one and three<\/small><\/p>\n
    Yeah, it’s not what I expected either, especially since:<\/p>\n
    @encode(__typeof__(s)) = [5c]\n@encode(__typeof__(&s)) = ^[5c]<\/pre>\n
    In fact, all of these are equvalent (modulo type warnings):<\/p>\n
    \nfoo(s);\nfoo(&s[0]);\nfoo(&(*s));\nfoo(&s);\n<\/pre>\n
    Explanation<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"
    Here’s a C-puzzler for you! given this function, void foo(char* s){ printf(“s is at: %p\\n s is: ‘%s’\\n”, s, s); } and that char s[] = “Joy!”; foo(s); prints out s is at: 0xbffff46b s is: ‘Joy!’ what will this next line print? foo(&s); \/\/WHAT WILL THIS DO? Pick all that apply: Print “Joy!” Print […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[53,18,7,5,4],"tags":[553,613,76,554],"class_list":["post-547","post","type-post","status-publish","format-standard","hentry","category-announcement","category-bug-bite","category-c","category-objective-c","category-programming","tag-arrays","tag-c","tag-gcc","tag-pointers"],"_links":{"self":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/547","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/comments?post=547"}],"version-history":[{"count":7,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/547\/revisions"}],"predecessor-version":[{"id":554,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/posts\/547\/revisions\/554"}],"wp:attachment":[{"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/media?parent=547"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/categories?post=547"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vgable.com\/blog\/wp-json\/wp\/v2\/tags?post=547"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}