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zzhang2006Flag for United States of America

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sscanf convert C-strings and floating point in one line

I have the follow C code to read a line from a file "store-data.txt" into a C string "record"
and then I use the sscanf to convert into two strings and a floating point with the format string:
 char format1[] = "%s %s %6.2f" and the file contains

"Royal_Crown  CrownRoyal  35.99"

The problem is it doen't read the floating point correctly while after taking the two strings.
The output was:

Got the record from the file: Royal_Crown  CrownRoyal 35.99
Royal_Crown  CrownRoyal  1.22298e-38

Thanks
------------------ The code:

char field_winename[20];
        char field_producer[20];
        float field_price;

 //
      ifstream infile("store-data.txt");
        infile.getline(record,80);   // read in a line from store-data.txt, into  "record"
        cout << "Got the record from the file: " << record << endl;

        num_words = sscanf(record,format1,field_winename,
                                          field_producer,
                                          &field_price
                          );
C

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Jaime Olivares
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evilrix
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Why not read the line into a std::string rather than a char array? Once it's in the string use the string to initialise an istringstream and then read the specific values of from that.

http://www.cplusplus.com/reference/iostream/istringstream/
http://www.cplusplus.com/reference/string/getline/
http://www.cplusplus.com/reference/string/string/


//Untested example
string line;

ifstream infile("store-data.txt");
getline(infline, line);
istringstream ss(line);

string field_winename;
string field_producer;
float field_price;

ss >> field_winename;
ss >> field_producer;
ss >> field_price;

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Jaime Olivares
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evilrix
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BTW are you away you only put this in the C zone but you are using C++ constructs? Would you like that zone added?
the question is very clear: sscanf convert C-strings and floating point in one line
So, it is a C-Language question, although other portions of the code are C++ related.
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evilrix
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>> although other portions of the code are C++ related.
Meaning it *is* C++ code meaning we *can* look at exploring C++ solutions. Thanks for telling a Zone Advisor how to do his job.
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zzhang2006
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ASKER

Thank you all!
Intinity08's solution worked and I will try Jaime's too.

That's all I need for now
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zzhang2006
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ASKER

thank again
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Infinity08
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jaime_olivares' post would help if the first two tokens (the strings) can contain spaces. It would not solve the problem with the floating point value though. ie. it's solving a different problem than the one you're having.

Do look into what evilrix suggested though. Using std::string's is easier and safer in most cases.
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Infinity08
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>> jaime_olivares' post would help if the first two tokens (the strings) can contain spaces.

Correction : that's not true. I misread what jaime_olivares suggested. Using %[^ ] allows the first two tokens to contain tabs, not spaces ;) On the condition that you use %[^ ] and not %[^ ]s ...
:)
C
C

C is a general-purpose, imperative computer programming language, supporting structured programming, lexical variable scope and recursion, while a static type system prevents many unintended operations. By design, C provides constructs that map efficiently to typical machine instructions, so it has found lasting use in applications that had formerly been coded in assembly language, including operating systems as well as various application software for computers ranging from supercomputers to embedded systems. It is distinct from C++ (which has its roots in C) and C#, and many later languages have borrowed directly or indirectly from C.

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