Trouble with a lab

This is a discussion on Trouble with a lab within the C Programming forums, part of the General Programming Boards category; Hi I've been perusing the board here for a couple weeks, and have found it to be a great resource ...

  1. #1
    null
    Join Date
    Dec 2005
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    18

    Trouble with a lab

    Hi

    I've been perusing the board here for a couple weeks, and have found it to be a great resource in learning C and C#. However, I can't find any answer to my current problem, which is part of a college homework assignment.

    Here's my code so far:
    Code:
    /************************
     *  CIS 15AG AM - Lab VII
     *
     * A program to help a business keep
     * statistics of its employee salaries
     * for one year.
     *
     * Author: Michael Baird
     *
     * Begin date: Nov 28, 2005
     * Last modified: Dec 4, 2005
    **/
    
    #include <stdio.h>
    
    char PromptUser();
    int CountEmployees();
    void HighestAnnualSalary();
    
    int main()
    {
        char choice;
    
        do
        {
            choice = PromptUser();
    
            switch( tolower( choice ) )
            {
                case 'c':
                    {
                        printf( "There are entries for %d employees.\n\n", CountEmployees() );
                    } break;
                case 'h':
                    {
                        HighestAnnualSalary();
                    } break;
            }
        } while( tolower( choice ) != 'q' );//(choice = tolower( PromptUser() )) != 'q' );
    
        system( "PAUSE" );
        return 0;
    }
    
    char PromptUser()
    {
        char res;
    
        printf( "Choose an option from the following menu:\n" );
        printf( "\tc: calculate total employees\n" );
        printf( "\th: report highest annual salary\n" );
        printf( "\ta: calculate average monthly salary\n" );
        printf( "\tf: format the report to output file\n" );
        printf( "\tq: quit this application\n\n" );
    
        printf( "Enter your choice: " );
        scanf( " %c", &res );
    
        return res;
    }
    
    int CountEmployees()
    {
        FILE * input;
        int count = 0;
        char holder;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return 1;
        }
    
        while( (fscanf( input, "%c", &holder ) != EOF) )
        {
            if( holder == '\n' )
            count++;
        }
    
        fclose( input );
        return count;
    }
    
    void HighestAnnualSalary()
    {
    
    }
    I'm stuck at calculating the highest annual salaray. It's supposed to read from an input file without using strings, structs, or arrays. Here's an excerpt from the input file:
    Code:
    1234,12,1200 2050 3010 4000 5560 6005 6780 5340 4000.50 3040 2005 1100
    The first int is the employee ID, and the second is the number of months the employee worked (the application is a business salary tracker). All the other numbers can be floats (but aren't in this example) and represent the amount earned in that month. So for example, January is at 1200, February at 2050, and December at 1100. I can't figure out how to pull those twelve floats out and do calculations without calculating the ID and the months worked as well.

    If I need to clarify anything, please let me know.

  2. #2
    Logic Junkie
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    fscanf seems the obvious choice. Read one int, the read one char to get rid of the comma, then read the second int, and read a char again to kill off the comma.

    Then, read one and one float and put them whereever you like (I would declare a float array the size of the months, dunno if you are allowed that in your assignment).

  3. #3
    null
    Join Date
    Dec 2005
    Posts
    18
    Unfortunately, I'm not allowed to use arrays at all :/

    Would your suggestion be like this (I apologize for not testing first, but I dont have an IDE at hand here):
    Code:
    fscanf( input, "%d%c%d%c%f...%f" );
    ?

  4. #4
    Registered User
    Join Date
    Mar 2005
    Posts
    140
    You don't need an array because there is no need to store all the values, you just need to keep track of the max.

    Code:
    max = 0;
    for each salary
      if salary > max
        max = salary
    return max
    you can read the first two values with two calls to fscanf like
    Code:
    fscanf( input, "%d,", &id );
    fscanf( input, "%d,", &num_of_months );
    then loop from 0 to < num_of months and read the salaries keeping track of the max as you go
    Code:
    loop num_of_month times
      fscanf( input, "%f", &salary );
    this only applies to a single line in the file. You'll need to do more to go through the entire file.
    Last edited by spydoor; 12-05-2005 at 03:09 PM.

  5. #5
    null
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    I see. So fscanf( ... ) doesn't go back to the start of the line if the call to the function ends? That's helpful info. Thanks, I'll get back to giving it a shot

  6. #6
    Logic Junkie
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    Nov 2005
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    31
    Oh, of course, you don't need an array - silly me.

    fscanf does not care for spaces if you ask it to read numbers, btw, so you would only need to read a char twice to kill the two commas.

  7. #7
    null
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    Dec 2005
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    Hrm. I've been battling this one again for a while. I dont understand why I'm so baffled by this, but I need support again. Here's what I have so far:
    Code:
    /************************
     *  CIS 15AG AM - Lab VII
     *
     * A program to help a business keep
     * statistics of its employee salaries
     * for one year.
     *
     * Author: Michael Baird
     *
     * Begin date: Nov 28, 2005
     * Last modified: Dec 4, 2005
    **/
    
    #include <stdio.h>
    
    char PromptUser();
    int CountEmployees();
    void HighestAnnualSalary();
    
    int main()
    {
        char choice;
    
        do
        {
            choice = PromptUser();
    
            switch( tolower( choice ) )
            {
                case 'c':
                    {
                        printf( "There are entries for %d employees.\n\n", CountEmployees() );
                    } break;
                case 'h':
                    {
                        HighestAnnualSalary();
                    } break;
            }
        } while( tolower( choice ) != 'q' );
    
        system( "PAUSE" );
        return 0;
    }
    
    char PromptUser()
    {
        char res;
    
        printf( "Choose an option from the following menu:\n" );
        printf( "\tc: calculate total employees\n" );
        printf( "\th: report highest annual salary\n" );
        printf( "\ta: calculate average monthly salary\n" );
        printf( "\tf: format the report to output file\n" );
        printf( "\tq: quit this application\n\n" );
    
        printf( "Enter your choice: " );
        scanf( " %c", &res );
    
        return res;
    }
    
    int CountEmployees()
    {
        FILE * input;
        int count = 0;
        char holder;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return 1;
        }
    
        while( (fscanf( input, "%c", &holder ) != EOF) )
        {
            if( holder == '\n' )
                count++;
        }
    
        fclose( input );
        return count;
    }
    
    void HighestAnnualSalary()
    {
        FILE * input;
        char holder;
        int i, j;
        int studentID, monthsWorked;
        float salary = 0, highestSalary = 0;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return;
        }
    
        for( j = 0; j < CountEmployees(); j++ )
        {
            while( (fscanf( input, "%c", &holder ) != EOF) )
            {
                fscanf( input, "%d,", &studentID );
                fscanf( input, "%d,", &monthsWorked );
    
                for( i = 0; i < monthsWorked; i++ )
                    salary += fscanf( input, "%f", &salary );
    
                if( salary > highestSalary )
                    highestSalary = salary;
            }
        }
        printf( "Highest salary: %.2f\n\n", highestSalary );
    }
    And here's the input:
    Code:
    1234,12,1200 2050 3010 4000 5560 6005 6780 5340 4000.50 3040 2005 1100
    2245,5,980   525 1120  405.50     650.50
    3496,3,      1020.50 2085  1050.50   
    8849,10,500.50 305.50 810 925 1060 1256.50   800.50 810.50 1087 578
    2390,6,875.50  1020  510.50  790  250.50  1000.50
    When I select 'h', it tells me the highest salary is 1101.00, and I don't know why. As to the input file, the first two numbers are employee ID and months worked respectively. The rest is the monthly salary, and if they didnt work that month then there's a space. It's damn confusing if you ask me, but it's already overdue so I can't complain.

    Any help would be greatly appreciated.

  8. #8
    Registered User
    Join Date
    Mar 2005
    Posts
    140
    When fscanf successfully reads one value it will return 1, so you are adding 1 to salary each time.

    Also, you are changing the value of salary before you compare/set it to highest, so you need a different variable to keep track of the total

    for highest annual salary of all employees you'd want something like
    Code:
        for( j = 0; j < CountEmployees(); j++ )
        {
            while( (fscanf( input, "%c", &holder ) != EOF) )
            {
                fscanf( input, "%d,", &studentID );
                fscanf( input, "%d,", &monthsWorked );
    
                for( i = 0; i < monthsWorked; i++ )
                {
                    fscanf( input, "%f", &salary );
                    total_salary += salary;
                }
                
                if( total_salary > highestSalary )
                {
                    highestSalary = total_salary;
                }
    
                total_salary = 0; //reset for each employee
            }
        }
        printf( "Highest salary: %.2f\n\n", highestSalary
    );
    Last edited by spydoor; 12-06-2005 at 11:41 AM.

  9. #9
    Logic Junkie
    Join Date
    Nov 2005
    Posts
    31
    fscanf() returns the number of items read and assigned, or EOF.

    Thus, your line
    Code:
    salary += fscanf( input, "%f", &salary );
    Does not do what you want. I am not sure what it does, but you'll get fantastic output.

    try this:
    Code:
    for( i = 0; i < monthsWorked; i++ )
        int ret = fscanf( input, "%f", &salary );
        //ret will let you know if you got EOF, or if fscanf failed somehow. 
        //as before onwards - salary now contains the newly read number, so just check it vs. highestSalary.

  10. #10
    Frequently Quite Prolix dwks's Avatar
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    Canada
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    Code:
    salary += fscanf( input, "%f", &salary );
    I think this was intended:
    Code:
    fscanf( input, "%f", &temp );
    salary += temp;
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


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  11. #11
    Frequently Quite Prolix dwks's Avatar
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    tolower() and family are in <ctype.h>.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ: cpwiki.sf.net

    My website: http://dwks.theprogrammingsite.com/
    Projects: codeform, xuni, atlantis, nort, etc.

  12. #12
    null
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    Thank you all so much. That's really helpful. I'm sure I'll be back with more questions (and I think I know why - after rereading the assignment, it's written very poorly, but my professor is a CIS major, not an English major), but thank you for all the help so far!

  13. #13
    null
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    One final question, and it's to do with formatting this input file into an output file. Here's the code so far:
    Code:
    /************************
     *  CIS 15AG AM - Lab VII
     *
     * A program to help a business keep
     * statistics of its employee salaries
     * for one year.
     *
     * Author: Michael Baird
     *
     * Begin date: Nov 28, 2005
     * Last modified: Dec 6, 2005
    **/
    
    #include <stdio.h>
    #include <ctype.h>
    
    char PromptUser();
    int CountEmployees();
    void HighestAnnualSalary();
    float CalculateHighestSalary( int * emp );
    void AverageMonthly();
    float CalculateAverageSalary();
    void FormatReport();
    int InputToOutput();
    
    int main()
    {
        char choice;
    
        do
        {
            choice = PromptUser();
    
            switch( tolower( choice ) )
            {
                case 'c':
                    {
                        printf( "There are entries for %d employees.\n\n", CountEmployees() );
                    } break;
                case 'h':
                    {
                        HighestAnnualSalary();
                    } break;
                case 'a':
                    {
                        AverageMonthly();
                    } break;
                case 'f':
                    {
                        FormatReport();
                    } break;
            }
        } while( tolower( choice ) != 'q' );
    
        system( "PAUSE" );
        return 0;
    }
    
    char PromptUser()
    {
        char res;
    
        printf( "Choose an option from the following menu:\n" );
        printf( "\tc: calculate total employees\n" );
        printf( "\th: report highest annual salary\n" );
        printf( "\ta: calculate average monthly salary\n" );
        printf( "\tf: format the report to output file\n" );
        printf( "\tq: quit this application\n\n" );
    
        printf( "Enter your choice: " );
        scanf( " %c", &res );
    
        return res;
    }
    
    int CountEmployees()
    {
        FILE * input;
        int count = 0;
        char holder;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return 1;
        }
    
        while( (fscanf( input, "%c", &holder ) != EOF) )
        {
            if( holder == '\n' )
                count++;
        }
    
        fclose( input );
        return count;
    }
    
    void HighestAnnualSalary()
    {
        int employee = 0;
        float highest = CalculateHighestSalary( &employee );
    
        printf( "Employee %d has the highest annual salary of %.2f.\n\n", employee, highest );
    
        return;
    }
    
    float CalculateHighestSalary( int * emp )
    {
        FILE * input;
        int i, j; //for use with loop methods
    
        int employeeID, monthsWorked;
        float highestSalary = 0, iSalary /*individual monthly salary*/ = 0, iTotalSalary = 0 /*individual total salary*/;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return 1;
        }
    
        for( j = 0; j < CountEmployees(); j++ )
        {
            while( fscanf( input, "%d,", &employeeID ) != EOF )
            {
                fscanf( input, "%d,", &monthsWorked );
    
                for( i = 0; i < monthsWorked; i++ )
                {
                    fscanf( input, "%f", &iSalary );
    
                    iTotalSalary += iSalary;
                }
    
                if( iTotalSalary > highestSalary )
                {
                    highestSalary = iTotalSalary;
                    *emp = employeeID;
                }
    
                //reset for each employee
                iSalary = 0;
                iTotalSalary = 0;
            }
        }
    
        fclose( input );
    
        return highestSalary;
    }
    
    void AverageMonthly()
    {
        printf( "The average monthly salary for all employees is: %.2f.\n\n", CalculateAverageSalary() );
    
        return;
    }
    
    float CalculateAverageSalary()
    {
        FILE * input;
        int i, j; //for use with loop methods
        int employeeID; //holder for this entry
    
        int totalMonths = 0, iMonthsWorked /*individual months worked*/;
        float totalAverage = 0, iSalary /*individual monthly salary*/;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening the input file.\n" );
            return 1;
        }
    
        for( j = 0; j < CountEmployees(); j++ )
        {
            while( fscanf( input, "%d,", &employeeID ) != EOF )
            {
                fscanf( input, "%d,", &iMonthsWorked );
                totalMonths += iMonthsWorked;
    
                for( i = 0; i < iMonthsWorked; i++ )
                {
                    fscanf( input, "%f", &iSalary );
    
                    totalAverage += iSalary; //store in totalAverage simply to save mem space
                }
            }
        }
    
        return (totalAverage / totalMonths);
    }
    
    void FormatReport()
    {
        if( InputToOutput() )
        {
            printf( "The input file has been successfully written to the output file, \'out.txt\'.\n\n" );
        }
        else
            printf( "Formatting failed.\n\n" );
    
        return;
    }
    
    int InputToOutput()
    {
        FILE * input;
        FILE * output;
        int i, j; //for use with loops
    
        int employeeID, monthsWorked;
        float jan, feb, mar, apr, may, jun, jul, aug, sep, oct, nov, dec;
    
        if( (input = fopen( "lab7_input.txt", "r" )) == NULL )
        {
            printf( "Error opening input file.\n" );
            return 0;
        }
        else if( (output = fopen( "out.txt", "w" )) == NULL )
        {
            printf( "Error creating output file.\n" );
            return 0;
        }
    
        for( j = 0; j < CountEmployees(); j++ )
        {
            while( fscanf( input, "%d,", &employeeID ) != EOF )
            {
                fscanf( input, "%d,", &monthsWorked );
    
                fprintf( output, "%d\t%d", employeeID, monthsWorked );
            }
        }
    }
    The two functions that are related to this question are the last two at the bottom there.

    The input file is this:
    Code:
    1234,12,1200 2050 3010 4000 5560 6005 6780 5340 4000.50 3040 2005 1100
    2245,5,980   525 1120  405.50     650.50
    3496,3,      1020.50 2085  1050.50   
    8849,10,500.50 305.50 810 925 1060 1256.50   800.50 810.50 1087 578
    2390,6,875.50  1020  510.50  790  250.50  1000.50
    As I said above, the first two ints represent the ID and the number of months worked. The rest are floats reprsenting the monthly salary earned. If the employee didnt work for a certain month, there's a space (I know, damn confusing to try and look at and determine which months the employee worked/didnt work). For example, if the employee worked January and March, but not February, there's an extra space between the first and third floats. Hope that makes sense, cause it took me an hour to figure it out.

    Anyway, here's my dilemma: I need to replace the "extra" spaces - those for unemployed months - with asteriks ( '*' ), while keeping the full float numbers in tact to also print those in between.

    You can see in the last function of my code that I also output the ID and the months worked, separated by tabs. After that, it's supposed to be either the monthly income or an asterik if unemployed for the month.

    I'll keep tinkering with what I've got above, but if I'm on the wrong track or if there are any great ideas (like all the ones above ), please help!

  14. #14
    ATH0 quzah's Avatar
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    Why don't you save yourself the trouble and write 0.0 to the file for when they don't work that month?


    Quzah.
    Hope is the first step on the road to disappointment.

  15. #15
    null
    Join Date
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    That'd be going against the rule of the lab, and in either case, I still don't know how to read a space versus an entire float (switching between %c or %f).

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