Question

I’m currently taking a course on “structured programming methods”. The course is not language based, but we generally use either C or C++. Sometimes I’m required to write in one of these languages, sometimes I have to initially write in C and covert the code to C++, and sometimes I am allowed to write in what I prefer. Quite possibly odd, I prefer to utilize C’s (f/p)rintf. So, here’s my issue:

This is my header file for the struct:

 #include <string>
 using namespace std;

 typedef string FNAME;
 typedef string LNAME;
 typedef string FULLNAME;
 typedef struct EmpRecord
 {
    FNAME firstname;
    LNAME lastname;
    FULLNAME fullname;
    float  hours, rate, deferred, gross, netpay,
           fedtax,  statetax,  ssitax;
  } EmpRecord;

Here’s the “main”.cpp:

        #define STRADD ", "
        #include <stdio.h>
        #include <iostream>
        #include <fstream>
        #include <iomanip>
        #include <string>
        #include "Struct.h"
        #include "Rates.h"
        #include "calcTaxesPlus.cpp"
        using namespace std;

        /*......*/
        void printEmpData(FILE *fp, struct EmpRecord *, float reghrs, float othrs);//3.8
        /*......*/
        int main()
        {
            float totRegHrs, totOtHrs, totRates, totGross, totDeferd,
                  totFed, totState, totSSI, totNet;
            float reghrs, othrs;
            float avgRate, avgRegHrs, avgGross, avgFed, avgSSI, avgNet,
                  avgOtHrs, avgState, avgDeferd;
            int   numEmp;

            EmpRecord emp;
            EmpRecord *Eptr;
            Eptr = &emp;

            FILE * fp;
            fp = fopen("3AReport.txt", "w");
            if (fopen == NULL)
            {
                printf("Couldn't open output file...!");
                fflush(stdin);
                getchar();
                exit(-1000);
            }
            /*....*/
            printEmpData(fp, Eptr, reghrs, othrs);//3.8
            return 0;
        }
        /*....*/
        void printEmpData(FILE *fp, struct EmpRecord *e, float reghrs, float othrs) 
        {
            fprintf(fp, "\n%-17.16s   %5.2f       %5.2f     %7.2f     %6.2f     %6.2f %7.2f", e->fullname, e->rate, reghrs, e->gross, e->fedtax, e->ssitax, e->netpay);
            fprintf(fp, "\n                                %5.2f                 %6.2f     %6.2f       \n", othrs, e->statetax, e->deferred);
        return;
    }

I have tried a ton of combinations suggested by other questions/answers, but none seem to be dealing with a cross-language situation.

I’m basically looking for a solution that permits me to continue to use fprintf while leaving the bulk of the code C++.

I’m not looking for someone to code the solution for me, rather to explain what the issues are with this and how to logically go about circumventing them.

Also, typedef is a requirement.
Thanks-

Answer 1

std::string has a c_str() const method that you can use to “prep” a std::string for formatting with %s:

fprintf(fp, "%s", e->fullname.c_str());

When a printf-style function sees %s in the format string, it is looking for a NUL-terminated C string (type: const char *). The std::string::c_str() const method returns just that for the std::string object.