[plz help]confusion about comparison between two strings to me

Dear guys~~
i met a problem which is spoiling me long time... i havent figure it out~
i am coding in linux...the following code shows the comparison of two strings... the size and the content are same but why it doesnt report "same"... plz help me...

Code:

---


bool FindRecord()
{
    char Seeker[MaxCallNumber];
    int SeekrPos = 0;
    cout << "Enter Call Namber: ";
    cin >> Seeker;
   
   
   
        fstream iofile("ass1.dat", ios::in | ios::out | ios::binary);
        if (!iofile)
        {
            cerr << "open error!" << endl;
            abort();   
        }
       
        while ((strcmp((Database[SeekrPos].CallNumber),Seeker) != 0) && (SeekrPos < NumBooks))
        {
                    cout << "Database[SeekrPos]:" << Database[SeekrPos].CallNumber << endl;
                cout << sizeof(Database[SeekrPos].CallNumber) << endl;
                cout << "Seeker: " << Seeker << endl;
                cout << sizeof(Seeker) << endl;
                SeekrPos++;
        }
       
        if (strcmp((Database[SeekrPos].CallNumber),Seeker) == 0)
        {
       
        cout << "found!!!"<< endl;
        iofile.seekg(SeekrPos*sizeof(Database[SeekrPos]),ios::beg);
        iofile.read((char*)&Database[SeekrPos],sizeof(Database[SeekrPos]));
        cout << "CallNumber: " << Database[SeekrPos].CallNumber << endl;
        cout << "Title: " << Database[SeekrPos].Title << endl;
        cout << "Author: " << Database[SeekrPos].Author << endl;
        cout << "BookStatus: " << Database[SeekrPos].BookStatus << endl;
        cout << "DueDate: " << Database[SeekrPos].DueDate << endl;
        cout << "BorrowersName: " << Database[SeekrPos].BorrowersName << endl;
        }
        else
        {
                cout << "couldn't find!!!";
        }
}

---

the konsole says that:

Enter command (or m for menu): f
Enter Call Namber: 001.645.2
Database[SeekrPos]:001.645.2
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.721.3
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.384.2
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.098.5
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.491.8
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.967.2
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.077.4
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.947.2
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.997.1
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.095.3
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.823.8
15
Seeker: 001.645.2
15
Database[SeekrPos]:001.812.9
15
Seeker: 001.645.2
15
Database[SeekrPos]:005.920.4
15
Seeker: 001.645.2
15
couldn't find!!!
========================

thx a lot!!!!

if i do it in DEV in windows,,, it works alright...

Can you output the Database[SeekrPos] and Seeker values with something around it to make sure there is no trailing whitespace or anything:

Code:

---

cout << "Seeker-->" << Seeker << "<--" << endl;

---

You can also output each letter (and maybe its ASCII value) for each string you pass to strcmp.

do i need to use this to reset all element in the array?

Code:

---

memset(ch,0x00,sizeof(ch));

---

btw why the size shows they are same?

i wonder why when the size and elements are same , but it reports "not same"

it still has the same problem...

sizeof returns the size of the array, but strcmp uses the length of the strings. These can be different. The string length is found by looking for the first null character (which is the character with the value 0x00). So even if the two arrays have a size of 15, it is possible that one has a string with 9 characters before the terminating null, and the other has a string of 10 characters (or some other number).

My guess is that by initializing the arrays to null characters, you no longer have garbage characters filling out the array after the actual string is loaded.

sry, i saw wrong... it still has the same problem... ................................ -. - OZN

What was the output when you added the --> <--?

output:

Code:

---

Enter command (or m for menu): f
Enter Call Namber: 001.645.2
<--Database[SeekrPos]001.645.2
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.721.3
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.384.2
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.098.5
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.491.8
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.967.2
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.077.4
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.947.2
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.997.1
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.095.3
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.823.8
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]001.812.9
15
Seeker-->001.645.2<--Seeker
15
<--Database[SeekrPos]005.920.4
15
Seeker-->001.645.2<--Seeker
15
couldn't find!!!

---

it has no space between <-- --> and "text"

wait... thats strange...~~~ why it is like that "<--Database[SeekrPos]001.823.8"

OMG

the position is totally strange!!!

if i change it to

Code:

---

cout << "11111Database[SeekrPos]-->" << Database[SeekrPos].CallNumber << "<--Database[SeekrPos]"<< endl;

---

the output is :

Code:

---

Enter command (or m for menu): f
Enter Call Namber: 001.645.2
<--Database[SeekrPos]s]-->001.645.2
15
Seeker-->001.645.2<--Seeker
15

---

something wrong with output buffer or something else?

where the hell is "s]" from.......... i am nearly crazy... 5:30am...

My guess is that there is a stray '\r' in there which might be why it is different on windows and linux. A carriage return will cause the cursor to go to the start of the line, which would be why the "<--" is at the start of the line instead of after the string.

How are you reading the data into the Database array? That's likely where the problem (or at least the solution) is.

Quote:

---

Originally Posted by kyaky

where the hell is "s]" from.......... i am nearly crazy... 5:30am...

---

You are probably printing back-spaces or some other "move the cursor" characters that happen to be the rubbish in some un-initialized variable - that would be my theory at least.

--
Mats

When you read a file in text mode, the carriage returns and linefeeds are automatically converted to a single character: '\n'. In binary mode that doesn't happen, though, so you may get different behavior depending on your platform.

Did you edit the file that has the records by hand (i.e. in an editor outside of your code)?

the txt is that:

Code:

---

001.645.2
Learning C++
Gregory        Harrison
1
001.721.3
C++ for Beginners
Quentin        Resnick
2
25 9 1999
Me
001.384.2
C++ Tools
Kieren Legrande
1

---

the reading is:

Code:

---

while(!InData.eof())
            {
                InData.getline(Database[NumBooks].CallNumber,MaxCallNumber+1,'\n');
                InData.getline(Database[NumBooks].Title,MaxTitle,'\n');
                InData.getline(Database[NumBooks].Author,MaxAuthor,'\n');       
                InData.getline(Database[NumBooks].BookStatus,MaxBookStatus,'\n');

                if (Database[NumBooks].BookStatus[0]=='2')
                        {
                    InData.getline(Database[NumBooks].DueDate,MaxDueDate);
                    for (int i = 0; i < MaxDueDate; i++)
                    {
                        if (Database[NumBooks].DueDate[i] == ' ')
                            Database[NumBooks].DueDate[i] = '/';
                    }
                   
                    InData.getline(Database[NumBooks].BorrowersName,MaxBorrowersName,'\n');
                }
                else
                {
                    strcpy(Database[NumBooks].DueDate,"N/A");
                    strcpy(Database[NumBooks].BorrowersName,"N/A");
                }
                NumBooks++;
            }
            InData.close();
            cout << "Txt file was successfully loaded!" << endl;

---

i think the reading has problem... but i dunno how to read... was i right to write like that?

Finally!!!! i found where the problem was... such a stupid i made again... the txt file has something wrong... because i made this txt file in windows it has 0D(CR) in this file... it made me crazy!!! i will be my biggest lesson in my life up to now... thank you alot... i love you guys!!!!!

6:15 am ... i can go to bed finally!!!!! OMG!!!