C++ RSS C++ RSS

Adding binary values from a file

Reply

•
•
Join Date: Dec 2006
Posts: 14
Reputation: DynamitMsk is an unknown quantity at this point 
Solved Threads: 0
DynamitMsk DynamitMsk is offline Offline
Newbie Poster

Adding binary values from a file

 
0
  #1
Dec 16th, 2006
Hello, I'm working o a function that takes a file with binary numbers and returns the sum of those numbers. Here's where I'm now

C++ Syntax (Toggle Plain Text) 
  1. int Sum (char *fileName)
  2. {
  3. char * numEnd;
  4. long temp(0);
  5. int result(0);
  6. string line;
  7.  ifstream file (fileName);
  8.   if (file.is_open())
  9.   {
  10.     while (! file.eof() )
  11.     {
  12.       getline (file,line);
  13. //Convert line to an long and sum up with the rest 
  14.       temp = strtol(line, &numEnd, 2);
  15.       result = result + temp;    
  16. //Done
  17.     }
  18. // close the stream
  19.     file.close();
  20.   }
  21. return result;
  22. }

and here's an error I'm getting when building it:
error C2664: 'strtol' : cannot convert parameter 1 from 'std::string' to 'const char *'

I thought strtol needed a pointer to the string, but changing line to pointer to line didn't help. Anyone can point me in a right direction?
Reply With Quote Quick reply to this message  
•
•
Join Date: Dec 2006
Posts: 14
Reputation: DynamitMsk is an unknown quantity at this point 
Solved Threads: 0
DynamitMsk DynamitMsk is offline Offline
Newbie Poster

Re: Adding binary values from a file

 
0
  #2
Dec 16th, 2006
OK, I got it. Any comments on code quality or improvements are still welcome!

C++ Syntax (Toggle Plain Text) 
  1. int Sum (char *fileName)
  2. {
  3. char * numEnd;
  4. long temp(0);
  5. int result(0);
  6. string line;
  7.  ifstream file (fileName);
  8.   if (file.is_open())
  9.   {
  10.     while (! file.eof() )
  11.     {
  12.       getline (file,line);
  13. //Convert line to an int and sum up with the rest 
  14.       char *linePt = &line[0];
  15.       temp = strtol(linePt, &numEnd, 2);
  16.       result = result + temp;    
  17. //Done
  18.     }
  19. // close the stream
  20.     file.close();
  21.   }
  22. return result;
  23. }
Reply With Quote Quick reply to this message  
•
•
Join Date: Apr 2006
Posts: 5,050
Reputation: John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold John A is a splendid one to behold 
Solved Threads: 331
Moderator
John A's Avatar
John A John A is offline Offline
Vampirical Lurker

Re: Adding binary values from a file

 
1
  #3
Dec 17th, 2006
It's because strtol was an old C function written far before C++ strings were invented. Although C++ strings have overloaded functions to make transitions from the older-style char strings to C++ strings and vice-versa, this problem can't be as transparently solved when passing a C++ string to a function that is expecting a char string. To remedy this, C++ strings include a nifty member function called c_str() that can quickly return the char string equivalent. Thus, you could code it like this:
C++ Syntax (Toggle Plain Text) 
  1. temp = strtol(line.c_str(), &numEnd, 2);

Better yet, use the C++ streams, the modern equivalent of a lot of the old C string functions, rather than mixing C and C++.

Hope this helps
"Technological progress is like an axe in the hands of a pathological criminal."
Reply With Quote Quick reply to this message  
Reply

Quick Reply to Thread
This thread is more than three months old.
Perhaps start a new thread instead?
•
•
•
•
•
•
•
•
Message:
•
•
•
•



Similar Threads
Other Threads in the C++ Forum
Thread Tools Search this Thread



6 api array based binary bitmap c++ c/c++ char class classes code coding compile console conversion count delete deploy desktop developer directshow dll download dwmapi dynamic dynamiccharacterarray email encryption error file forms fstream function functions game givemetehcodez graph gui hangmangame happy homeworkhelp homeworkhelper iamthwee ifstream input int integer java job lib linkedlist linker loop looping loops map math matrix memory mobile modal multiple news node number numbertoword output parameter pointer problem program programming project python random read recursion reference rpg snakes string strings temperature template templates test text text-file tree url variable vector video win32 windows winsock word wordfrequency wxwidgets
About Us | Contact Us | Advertise | DaniWeb | Acceptable Use Policy | RSS Feed

©2003 - 2009 DaniWeb® LLC