{"id":5117,"date":"2014-03-30T19:02:23","date_gmt":"2014-03-30T19:02:23","guid":{"rendered":"https:\/\/unknownerror.org\/index.php\/2014\/03\/30\/problem-about-ctype-collection-of-common-programming-errors\/"},"modified":"2014-03-30T19:02:23","modified_gmt":"2014-03-30T19:02:23","slug":"problem-about-ctype-collection-of-common-programming-errors","status":"publish","type":"post","link":"https:\/\/unknownerror.org\/index.php\/2014\/03\/30\/problem-about-ctype-collection-of-common-programming-errors\/","title":{"rendered":"problem about ctype-Collection of common programming errors"},"content":{"rendered":"<ul>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/1719392531c762e6f4f09a254850997f?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nAlex Essilfie<br \/>\nvb.net casting directcast ctype<br \/>\nEver since I moved from VB6 to VB.NET somewhere in 2005, I&#8217;ve been using CType to do casting from one data type to another. I do this because it is simply faster to type, used to exist in VB6 and I do not know why I have to be using DirectCast if there is apparently no difference between them.I use TryCast once in a while because I understand that sometimes casting can fail. I however cannot get the difference between CType and DirectCast.Can anyone tell me the difference in plain simple English<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/c838b4a7a51b2b15050341630d2e39d6?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nBrij<br \/>\n.net vb.net ctype<br \/>\nIn VB.NET CType can be used to convert one type to another.CType(expression,type)I have the &#8220;expression&#8221; stored in an instance object class, say &#8220;objExp&#8221;. I have the &#8220;type&#8221; stored in an instance of Type class, say&#8221;objType&#8221;.I am trying CType(objExp, objType) I am getting compile error, how should I go about it ? &#8220;objType&#8221; is fetched and assigned at runtime.<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/8c78b970aac9302a50c3d646b916c1e6?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nJ. Steen<br \/>\nvb.net casting ctype<br \/>\nI would like to be able to cast a value dynamically where the type is known only on runtime. Something like this:myvalue = CType(value, &#8220;String, Integer or Boolean&#8221;)The string that contains the type value is passed as argument and also read from a database, and the value is stored as string in the databaseIs this possible?<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/ee73700af97e245d502bc0664972931b?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nuser1655331<br \/>\nvb.net ctype dynamictype<br \/>\nI would like to know if this is ok, lets say I have a class somewhere on my project and at some point I will need to cast an object to this class type or another but I can only know this at runtime, so at design time can I do something like this??Dim obj = &#8216;will be assigned something of some type. Dim typeObj As Type = Type.GetType(&#8220;xxxx.Foo&#8221;) Dim fooVar As Foo = CTypeDynamic(obj, typeObj)will this work as lets says:Dim x As String = &#8220;3&#8221; Dim n As Integer = CType(x, Integer)<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/5b1764e41ab6cbd617ed858814b3b84e?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nElite Mx<br \/>\nc99 integer-overflow ctype<br \/>\nWhat is the proper way to deal with character values which when casted to an unsigned char fall between {INT_MAX + 1 &#8230; UCHAR_MAX} where UCHAR_MAX is greater than INT_MAX.int is_digit(char c) {unsigned char uchar = c;if(uchar &gt; INT_MAX)return MAYBE;return isdigit((int)uchar) ? YES : NO; }<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/75ee864ee3bef78f2a144398789fed25?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nJens<br \/>\nc compiler-warnings ctype<br \/>\nI have the following code to read an argument from the command line. If the string is 1 character long and a digit I want to use that as the exit value. The compiler gives me a warning on the second line (array subscript has type &#8216;char&#8217; ) This error comes from the second part after the &#8220;&amp;&amp;&#8221; .if (args[1] != NULL) {if ((strlen(args[1]) == 1) &amp;&amp; isdigit(*args[1]))exit(((int) args[1][0]));elseexit(0);} }Also, when I use a different compiler I get two errors on the next line (exit)<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/i.stack.imgur.com\/B8r65.png?s=32&amp;g=1\" \/><br \/>\njamesdlin<br \/>\nc ctype<br \/>\nThe various is&#8230; functions (e.g. isalpha, isdigit) in ctype.h aren&#8217;t entirely predictable. They take int arguments but expect character values in the unsigned char range, so on a platform where char is signed, passing a char value directly could lead to undesirable sign extension. I believe that the typical approach to handling this is to explicitly cast to an unsigned char first.Okay, but what is the proper, portable way to deal with the various isw&#8230; functions in wctype.h? wchar_t, like c<\/li>\n<li><img decoding=\"async\" src=\"http:\/\/www.gravatar.com\/avatar\/db869d4e8c636d15bd18678f6ced444b?s=32&amp;d=identicon&amp;r=PG\" \/><br \/>\nShafik Yaghmour<br \/>\nc c11 ctype<br \/>\nTraditionally, it was strictly speaking an error to pass a signed char to the ctype.h predicates because they were only defined for -1 to 255, so -128 to -2 could end up reading outside array bounds.Was this ever fixed, or do you still strictly speaking have to use unsigned char to avoid undefined behavior in modern versions of C?<\/li>\n<\/ul>\n<p>Web site is in building<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Alex Essilfie vb.net casting directcast ctype Ever since I moved from VB6 to VB.NET somewhere in 2005, I&#8217;ve been using CType to do casting from one data type to another. I do this because it is simply faster to type, used to exist in VB6 and I do not know why I have to be [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-5117","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/5117","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=5117"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/5117\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=5117"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=5117"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=5117"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}