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C++ Reading from a text file

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Join Date: May 2007

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C++ Reading from a text file

May 13th, 2007

Hello,

I am trying to read data from a text file in the following format:
05 mike smith 30.00 2 1

so the format is: int, character[21] = max size of array, double, int, int

I am trying to read the values into an array of objects. I can read the first int and the name fine but I can't read in the rest of the values. Heres my code:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
 numEmp = 0;
    empFile >> id;
    empFile.ignore(); // Discard space before name
    empFile.getline(name, 21, '\n'); // Store up to 20 characters
    empFile >> rate >> dep >> type; //I think this is the problem
 
    while (empFile && numEmp < MAX_EMP)
    {
         // Move new employee info into array and increment numEmp count
         Emp[numEmp].set(id, name, rate, dep, type);
         numEmp++;
 
         // Get next employee info
         empFile >> id;
         outputFile << id << endl;
         empFile.ignore(); // Discard space before name
         empFile.getline(name, 21, '\n'); // Store up to 20 characters
         empFile >> rate >> dep >> type;
    }
 numEmp = 0;
    empFile >> id;
    empFile.ignore(); // Discard space before name
    empFile.getline(name, 21, '\n'); // Store up to 20 characters
    empFile >> rate >> dep >> type; //I think this is the problem
 
    while (empFile && numEmp < MAX_EMP)
    {
         // Move new employee info into array and increment numEmp count
         Emp[numEmp].set(id, name, rate, dep, type);
         numEmp++;
 
         // Get next employee info
         empFile >> id;
         outputFile << id << endl;
         empFile.ignore(); // Discard space before name
         empFile.getline(name, 21, '\n'); // Store up to 20 characters
         empFile >> rate >> dep >> type;
    }

Last edited by Ancient Dragon; May 13th, 2007 at 1:00 am. Reason: changed code tags to add line numbers

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Re: C++ Reading from a text file

May 13th, 2007

discard the spaces between the name/rate/dep/type

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Re: C++ Reading from a text file

May 13th, 2007

Line 3 can be deleted because the stream's extraction operaotr >> will ignore all white space (spaces and tabs) between words.

Line 4: you don't want to use getline() here because it reads the entire line, not just the next two words. If the name is always in the format you show then its probably better and easier to use the extractions operator >> to read the first name and last name separately.

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C++ Syntax (Toggle Plain Text)

string firstName,lastName;
empFile>> firstName >> lastName;
// now concantinate them together
string name = firstName + " " + lastName;

line 5 should work ok if you make the above changes

Last edited by Ancient Dragon; May 13th, 2007 at 1:11 am.

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Re: C++ Reading from a text file

May 13th, 2007

Thanks for the response.

The only problem is that I need to ultimately store the name, both first and last name into a character array which is apart of a class object. I tried

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 strcpy(name, tempName); //where tempName is a string
 strcpy(name, tempName); //where tempName is a string

I get an error with that syntax; what is the correct way to copy a string into an array?

Also, is it possible to take in the entire line of input into one array and then extract the specific variables?

Thanks

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Re: C++ Reading from a text file

May 13th, 2007

I got around the issue of copying the string into an array using the following code:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
 // tempName is a string, name is an array of characters
 tempName.copy(name, 21, 0);
 // tempName is a string, name is an array of characters
 tempName.copy(name, 21, 0);

Last edited by rockthrower; May 13th, 2007 at 5:40 pm. Reason: Formatting

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Re: C++ Reading from a text file

May 13th, 2007

I am only able to copy in the first line of data from the text file but not the rest. For some reason, it is not looping until empFile && empNum are less than MAX_EMP:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
<ol style="list-style-type: decimal"><li>const int MAX_EMP = 100;</li>
<li>int numEmp = 0;</li>
<li>empFile >> id;</li>
<li>empFile >> firstName >> lastName; // Extract first and last name</li>
<li>tempName = firstName + " " + lastName; // Concantinate both names</li>
<li>tempName.copy(name, 21, 0);</li>
<li>empFile >> rate >> dep >> type; // Extract rest of varbiables</li>
<li>while (empFile && numEmp < MAX_EMP)</li>
<li>{</li>
<li>// Move new employee info into array and increment numEmp count</li>
<li>Emp[numEmp].set(id, name, rate, dep, type);</li>
<li>numEmp++;</li>
<li>// Get next employee info</li>
<li>empFile >> id;</li>
<li>empFile >> firstName >> lastName; // Extract first and last name</li>
<li>tempName = firstName + " " + lastName; // Concantinate both names</li>
<li>tempName.copy(name, 21, 0);</li>
<li>empFile >> rate >> dep >> type; // Extract rest of varbiables</li>
<li>}</li>
</ol>
<ol style="list-style-type: decimal"><li>const int MAX_EMP = 100;</li>
<li>int numEmp = 0;</li>
<li>empFile >> id;</li>
<li>empFile >> firstName >> lastName; // Extract first and last name</li>
<li>tempName = firstName + " " + lastName; // Concantinate both names</li>
<li>tempName.copy(name, 21, 0);</li>
<li>empFile >> rate >> dep >> type; // Extract rest of varbiables</li>
<li>while (empFile && numEmp < MAX_EMP)</li>
<li>{</li>
<li>// Move new employee info into array and increment numEmp count</li>
<li>Emp[numEmp].set(id, name, rate, dep, type);</li>
<li>numEmp++;</li>
<li>// Get next employee info</li>
<li>empFile >> id;</li>
<li>empFile >> firstName >> lastName; // Extract first and last name</li>
<li>tempName = firstName + " " + lastName; // Concantinate both names</li>
<li>tempName.copy(name, 21, 0);</li>
<li>empFile >> rate >> dep >> type; // Extract rest of varbiables</li>
<li>}</li>
</ol>

Last edited by rockthrower; May 13th, 2007 at 6:16 pm. Reason: Formatting

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Re: C++ Reading from a text file

May 13th, 2007

Rockthrower, don't manually use [list] bbcode to create line numbers. Instead use [code=c] or [code=cplusplus] bbcode.

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Re: C++ Reading from a text file

May 13th, 2007

I realized that it was not looping because i was not taking in the very last character in the line. I initialized a new variable to take in the last character and although it loops now, it still does not loop through the entire file nor does it read the correct numbers after the double amount. Below is a sample of the text file I am reading in:

5 Christine Kim 30.00 2 1 F
15 Ray Allrich 10.25 0 0 M
16 Adrian Bailey 12.50 0 0 F
17 Juan Gonzales 30.00 1 1 M
18 Morris Kramer 8.95 0 0 M

The first integar, the name and the double amount are stored correctly but the last two integars and the last character are not stored correctly. My revised code is:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
 
numEmp = 0;
empFile >> id;
empFile >> firstName >> lastName; // Extract first and last name
tempName = firstName + " " + lastName; // Concantinate both names
tempName.copy(name, 21, 0); // Copy string into array called name
empFile >> rate >> type >> sex; // Extract the rest of the variables in line
 
while (empFile && numEmp < MAX_EMP)
    {
         // Move new employee info into array and increment numEmp count
         Emp[numEmp].set(id, name, rate, dep, type);
         numEmp++;
 
         // Get next employee info
         empFile >> id;
         empFile >> firstName >> lastName; // Extract first and last name
         tempName = firstName + " " + lastName; // Concantinate both names
         tempName.copy(name, 21, 0); // Copy string into array called name
         empFile >> rate >> type >> sex; // Extract the rest of the variables in line
    }
 
numEmp = 0;
empFile >> id;
empFile >> firstName >> lastName; // Extract first and last name
tempName = firstName + " " + lastName; // Concantinate both names
tempName.copy(name, 21, 0); // Copy string into array called name
empFile >> rate >> type >> sex; // Extract the rest of the variables in line
 
while (empFile && numEmp < MAX_EMP)
    {
         // Move new employee info into array and increment numEmp count
         Emp[numEmp].set(id, name, rate, dep, type);
         numEmp++;
 
         // Get next employee info
         empFile >> id;
         empFile >> firstName >> lastName; // Extract first and last name
         tempName = firstName + " " + lastName; // Concantinate both names
         tempName.copy(name, 21, 0); // Copy string into array called name
         empFile >> rate >> type >> sex; // Extract the rest of the variables in line
    }

Last edited by rockthrower; May 13th, 2007 at 7:05 pm. Reason: formatting

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Re: C++ Reading from a text file

May 13th, 2007

does Emp.set() copy name into another class variable? If it does then you don't neet 6 or 19, but you can use string's c_str() method instead to pass a char* to that function, like this:

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(Toggle Plain Text)

Emp[numEmp].set(id, tempName.c_str(), rate, dep, type);

I think you will need to post the rest of your program so we can see class declaration and other code. What you posted appears to be ok so the problem is probably elsewhere.

Last edited by Ancient Dragon; May 13th, 2007 at 7:27 pm.

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Re: C++ Reading from a text file

#10

May 14th, 2007

Also, "are not stored correctly" does not give enough information. Explain what actually does happen, because the result of the error may be important to understanding the problem.

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