Functions (Pass by reference/value)

[mo812]

Attempting to edit a code to utilize a function instead of previously used method to calculated percentage of failures. Objective is to use only one function. However, I cannot figure it out. The best I was able to reason was with 4 functions. I will be posting the original code as well as my 4 function (wrong) attempt and exclude the cout/outfile portions. Thank you in advance.

[Original code]
#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;
int main ()

{int ftemp(0), fpres(0), ftime(0), fbatch(0), count(0); //need to declare variables for counters of failed values

double batch, temp, pres, time; //need to declare doubles for values being inputted from file

ifstream infile;

infile.open("abc.txt"); //open file with data

while (infile>>batch>>temp>>pres>>time) //order of reading values in file

{
if (temp<150 || temp>170) //temp unacceptable range
ftemp++; //failed temp counter

if (pres<60 || pres>70) //pressure unacceptable range
fpres++; //failed pressure temp counter

if (time<2.00 || time>2.50) //time unacceptable range
ftime++; //failed time counter

if (temp<150 || temp>170 || pres<60 || pres>70 || time<2.00 || time>2.50) //find any unacceptable peice of data

fbatch++; //unacceptable batch counter
if (batch>0)
count++; //counter value increase as batch value is accepted

}

double tep, pp, tip, bp; //initiate percentage values
tep = (ftemp/25.0)*100; //formula for percentage
pp = (fpres/25.0)*100;//formula for percentage
tip = (ftime/25.0)*100;//formula for percentage
bp = (fbatch/25.0)*100;//formula for percentage

infile.close(); //done with infile

return 0;

}
[/Original code]






[Attempt Code]

#include <iostream>
#include <fstream>
#include <cstdlib>
using namespace std;

int FailPerTemp (double failtemp);
int FailPerPres (double failpres);
int FailPerTime (double failtime);
int FailPerBatch (double failbatch);

int main ()
{
int ftemp(0), fpres(0), ftime(0), fbatch(0), count(0);

double batch, temp, pres, time;

double ftempfail, fpresfail, ftimefail, fbatchfail;

ifstream infile;

infile.open("abc.txt"); //open file with data

while (infile>>batch>>temp>>pres>>time) //order of reading values in file
{
if (temp<150 || temp>170) //temp unacceptable range
ftemp++; //failed temp counter

if (pres<60 || pres>70) //pressure unacceptable range
fpres++; //failed pressure temp counter

if (time<2.00 || time>2.50) //time unacceptable range
ftime++; //failed time counter

if (temp<150 || temp>170 || pres<60 || pres>70 || time<2.00 || time>2.50) //find any unacceptable peice of data

fbatch++; //unacceptable batch counter
if (batch>0) //counter
count++; //counter value increase as batch value is accepted
}

ftempfail= FailPerTemp(ftemp);
fpresfail= FailPerPres(fpres);
ftimefail= FailPerTime(ftime);
fbatchfail= FailPerBatch (fbatch);

infile.close(); //done with infile

}

int FailPerTemp (double failtemp)
{
double calcftemp;
calcftemp=failtemp/25*100;
}

int FailPerPres (double failpres)
{double calcfpres;
calcfpres=failpres/25*100;
}

int FailPerTime (double failtime)
{double calcftime;
calcftime=failtime/25*100;
}

int FailPerBatch (double failbatch)
{double calcfbatch;
calcfbatch=failbatch/25*100;
}


[/Attempt Code]

[Ganado]

int FailPerTemp (double failtemp)
{
double calcftemp;
calcftemp=failtemp/25*100;
}

// ... and the rest

You should read the tutorial on functions http://www.cplusplus.com/doc/tutorial/functions/

int FailPerTemp (double failtemp); means that it the function takes in a double as a parameter and returns an int. But none of your functions return anything, much less a double value.

You probably want something like this:

double FailPerTemp(double failtemp); // function prototype

// ...

double FailPerTemp (double failtemp)
{
    double calcftemp = failtemp/25.0*100.0;
    return calcftemp;
}

[mo812]

Thanks for the link! i'll check it out.

Would the same concept apply if I want to use all failed values(based on the counter) in one function for their respective percentages?

[Ganado]

Not exactly sure what you mean, but a function can only return one value. So you can't return multiple values. Otherwise, yes, a function will work as intended as long as you return what is needed (or make the type of the function "void" if you don't want to return anything).