c++ - Why I have to give a negative two offset for seekg for end of file -


so reading file handling , wanted read text file end. decided seek pointer last character using,

seekg(-2,ios::end);

my complete code is:

fin.open("source.txt"); fin.seekg(-2,ios::end);  fin>>ch; if(fin.fail())     cout<<"uh oh!"; else     cout<<ch;

my question why have make offset -2 , not -1 assume ios::end places pointer 1 position after last valid character of file.

any help? thanks.

the reason of error use >> , have last character '\n' or space.

seeking -1 positions on '\n', ignored extractor >> (it skips whitespaces , '\n'). if position 1 character before, -2, on last non space character , works.

to see what's going on @ end of file: 

in.open("source.txt"); fin.seekg(-1,ios::end);  // -1 last char of file   ch = fin.get();  // read 1 character without ignoring if(fin.fail())     cout<<"uh oh!"; else     cout<<(int)ch <<"="<<ch<<endl;  // display char code (if not printable) , char

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