C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Question about type conversion and casting          C++Talk.NET Forum Index -> C++ language (comp.lang.c++) View previous topic :: View next topic   Author Message seia0106 Guest Posted: Mon Jul 28, 2003 4:54 pm    Post subject: Question about type conversion and casting Hello I am writing a function to read a binary file. Here is a part of code #include <fstream> .. .. BYTE *pData; long lDataLen; pms->GetPointer(&pData); lDataLen = pms->GetSize(); // Read one line at a time till end of file.. if (m_inFile.getline(pData, lDataLen))pms->SetActualDataLength(strlen((char*)pData)+1); else {return S_FALSE;} ................... The error message that i get is this error C2664: 'class std::basic_istream<char,struct std::char_traits &__thiscall std::basic_istream<char,struct std::char_traits::getline(char *,int)' : cannot convert parameter 1 from 'unsigned char *' to 'char *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast Conflict in datatypes is causing this error. How can i solve this problem? Which type of casting is better here and how it should be used here. thanks Back to top John Harrison Guest Posted: Mon Jul 28, 2003 5:47 pm    Post subject: Re: Question about type conversion and casting "seia0106" <miahmed67 (AT) yahoo (DOT) com> wrote Quote: Hello I am writing a function to read a binary file. Here is a part of code #include <fstream . . BYTE *pData; long lDataLen; pms->GetPointer(&pData); lDataLen = pms->GetSize(); // Read one line at a time till end of file.. if (m_inFile.getline(pData, lDataLen))pms->SetActualDataLength(strlen((char*)pData)+1); else {return S_FALSE;} .................. The error message that i get is this error C2664: 'class std::basic_istream<char,struct std::char_traits &__thiscall std::basic_istream<char,struct std::char_traits::getline(char *,int)' : cannot convert parameter 1 from 'unsigned char *' to 'char *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast Conflict in datatypes is causing this error. How can i solve this problem? Which type of casting is better here and how it should be used here. thanks Why are you trying getline in a binary file? getline is for text files. Anyway you can cast pData to the required type, one of the few common instances where a cast is justified. if (m_inFile.getline((char*)pData,lDataLen)) But the fact that you cast pData to (char*) twice, suggests that maybe you would do better to declare is as char* in the first place. After all it does appear to be text data, and char* is used for text. john Back to top seia0106 Guest Posted: Tue Jul 29, 2003 1:14 pm    Post subject: Re: Question about type conversion and casting Thank you for the reply. The file is a text file. I have tried to do it the way you said but it is still not working. In this function *pData must be declared as a 'BYTE'type. So how to use a 'BYTE' type *pData as a first parameter of getline() method and in strlen()? The error is same that "cannot convert parameter 1 from 'const char ** ' to 'unsigned char ** '" I have looked into the text books for unsigned char type, char type and signed char type but I am little confused about their differences and uses. thanks in advance "John Harrison" <john_andronicus (AT) hotmail (DOT) com> wrote Quote: "seia0106" <miahmed67 (AT) yahoo (DOT) com> wrote in message news:4fe296bd.0307280854.7e7fa0cb (AT) posting (DOT) google.com... Hello I am writing a function to read a binary file. Here is a part of code #include <fstream . . BYTE *pData; long lDataLen; pms->GetPointer(&pData); lDataLen = pms->GetSize(); // Read one line at a time till end of file.. if (m_inFile.getline(pData, lDataLen))pms->SetActualDataLength(strlen((char*)pData)+1); else {return S_FALSE;} .................. The error message that i get is this error C2664: 'class std::basic_istream<char,struct std::char_traits &__thiscall std::basic_istream<char,struct std::char_traits::getline(char *,int)' : cannot convert parameter 1 from 'unsigned char *' to 'char *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast Conflict in datatypes is causing this error. How can i solve this problem? Which type of casting is better here and how it should be used here. thanks Why are you trying getline in a binary file? getline is for text files. Anyway you can cast pData to the required type, one of the few common instances where a cast is justified. if (m_inFile.getline((char*)pData,lDataLen)) But the fact that you cast pData to (char*) twice, suggests that maybe you would do better to declare is as char* in the first place. After all it does appear to be text data, and char* is used for text. john Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         C++Talk.NET Forum Index -> C++ language (comp.lang.c++) All times are GMT Page 1 of 1   Jump to: Select a forum C/C++----------------C LanguageC Language (Moderated)C++ Language (Moderated)C++ language (comp.lang.c++)C++ language, library and standards Non-English C/C++ Newsgroups----------------C++ (German)C++ (French)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.