Need help in converting C++ to C

[optimum]

hi i am kind of new to programming, i have managed to create a simple payroll database in C++, but now i am trying to convert in into C but i am keep getting error, can anyone help me convert this code to C. I really need this so thatr i can learn my mistakes in C. Below is the C++ code that i have have developed.
Thank you,

#include<fstream>
#include<string>
#include<iostream>
#include<iomanip>
using namespace std;
struct employee{ string fname, lname;
double hourlyrate, hoursworked, netpay; }; //employee
employee e[100];
int n=0;
void load(){
ifstream fin("employee.txt",ios::in);
while(fin>>e[n].fname>>e[n].lname>>e[n].hourlyrate>>e[n].hoursworked){
e[n].netpay=e[n].hourlyrate*e[n].hoursworked;
n++;}//WHILE
}//LOAD
void store(){
ofstream fout("employee.txt",ios::out);
for(int i=0; i<n; i++){
if(e[i].fname!=" ")
fout<<e[i].fname<<" "<<e[i].lname<<" "<<e[i].hourlyrate<<" "<<e[i].hoursworked<<endl;
}//FOR
}//STORE
 
void insert(){
cout<<"Enter employee's first name: "; cin>>e[n].fname;
cout<<"Enter employee's last name: "; cin>>e[n].lname;
cout<<"Enter employee's salary per hour: "; cin>>e[n].hourlyrate;
if(cin.fail())
{cout<<"Error\n"; exit(1);}
cout<<"Enter employee's hours worked: ";
cin>>e[n].hoursworked;
e[n].netpay=e[n].hourlyrate*e[n].hoursworked;
n++; }//INSERTS THE RECORD TO ARRAY
 
void display(){
cout<<setiosflags(ios::left)<<setw(15)<<"First Name"<<setw(15)<<"Last Name";
cout<<setw(10)<<"Hourly Rate"<<setw(10)<<"HrsWorked"<<setw(10)<<"Net Pay";
cout<<endl<<endl;
cout<<setiosflags(ios::fixed|ios::showpoint|ios::left);
for(int i=0;i<n;i++){
if(e[i].fname!=" "){ 
cout<<setiosflags(ios::left)<<setw(15)<<e[i].fname<<setw(15)<<e[i].lname;
cout<<setprecision(2)<<setiosflags(ios::left)<<setw(10)<<e[i].hourlyrate;
cout<<setw(10)<<e[i].hoursworked<<setw(10)<<e[i].netpay;
cout<<resetiosflags(ios::left)<<endl;}//IF
}//FOR
}//THIS FUNCTION DISPLAYS ALL RECORDS IN ARRAY
 
int search(string s){
for(int i=0;i<n;i++)if(s==e[i].lname)return i;//FOR
return -1;
}//SEARCH BY NAME,-1 NOT FOUND
 
void update(){
string searchn;
cout<<"Enter the Last Name of the Employee to be modified: "; cin>>searchn;
int i=search(searchn); 
if(i==-1) cout<<"EMPLOYEE NOT LISTED"<<endl;
else{
cout<<endl<<"Please enter the updated information."<<endl;
cout<<"Enter employee's first name: "; cin>>e[i].fname;
cout<<"Enter employee's last name: "; cin>>e[i].lname;
cout<<"Enter employee's rate per hour: "; cin>>e[i].hourlyrate;
cout<<"Enter employee's hours worked: "; cin>>e[i].hoursworked;
e[i].netpay=(e[i].hourlyrate*e[i].hoursworked);}
}//UPDATE
 
void deleterec(){
string searchn;
cout<<"Enter the Last Name of the Employee to delete: "; cin>>searchn;
int k=-1;
for(int j=0; j<n;j++){
if(searchn==e[j].lname)
k=j;}
if(k!=-1)
{ cout<<" Name: "<<e[k].fname<<" "<<e[k].lname<<endl;
cout<<" Salary: "<<e[k].hourlyrate<<endl;
cout<<" Hrs Worked: "<<e[k].hoursworked<<endl;
cout<<" Net Pay: "<<e[k].netpay<<endl<<endl;}
 
char ans;
cout<<endl<<"Do you want to delete this record? (Y/N): ";
cin>>ans;
if(ans=='Y'||ans=='y'){
e[k].fname=" ";}//IF
else cout<<"EMPLOYEE NOT FOUND"; }//DELETE
 
void report(){
int i=0;
double totalhrs=0.00, totalpay=0.00;
for(i=0;i<n;i++){
totalhrs+=e[i].hoursworked;
totalpay+=e[i].netpay; }//FOR
cout<<"Total number of employees: " <<n<<endl<<endl;
cout<<"Total hours worked by all employees: "<<totalhrs<<endl<<endl;
cout<<"Total pay of all employees: "<<totalpay<<endl<<endl; }//REPORT
 
void deletefile(){
int pword;
cout<<"Enter your administrative password: "; cin>>pword;
if(pword==0000){
ofstream record("employee.txt", ios::out);
record<<endl;
load();
record.close();}
else cout<<"Wrong password entered."<<endl; }//DELETE FILE
 
void backupfile(){
system("copy employee.txt backup.txt");
cout<<endl<<"Back-up file has been made."<<endl;
}//BACKUPFILE use cp command for UNIX
 
void main(){
load();
char choice='0';
while (choice!='e'&&choice!='E'){
cout<<endl<<"Payroll Database"<<endl;
cout<<"1. Insert Employee Record and Compute Net Pay"<<endl;
cout<<"2. Display All Records"<<endl;
cout<<"3. Search Database"<<endl;
cout<<"4. Update Record"<<endl;
cout<<"5. Delete Record"<<endl;
cout<<"6. Generate Report"<<endl;
cout<<"7. Delete Database File"<<endl;
cout<<"8. Back-up Database File"<<endl;
cout<<endl<<" Type e to exit"<<endl<<endl;
cout<<"Enter the number of your choice:";
cin>>choice; cout<<endl;
switch (choice){
case '1': insert(); break;
case '2': display(); break;
case '3': char s[100]; int index;
cout<<"Enter the last name of the person you want: ";
cin>>s;
index=search(s);
if(index!=-1) {
cout<<"Name: "<<e[index].fname<<" "<<e[index].lname<<endl;
cout<<"Hourly Rate: "<<e[index].hourlyrate<<endl;
cout<<"Hrs Worked: "<<e[index].hoursworked<<endl;
cout<<"Net Pay: "<<e[index].netpay<<endl<<endl;}//IF
else cout<<"EMPLOYEE NOT FOUND"<<endl;
break;
case '4': update(); break;
case '5': deleterec(); break;
case '6': report(); break;
case '7': deletefile(); break;
case '8': backupfile(); break;
case 'e': store(); break; //EXIT
default: cout<<"Invalid Choice"<<endl; break; }//SWITCH
}//WHILE
}//MAIN

[sicarie]

Well, you're going to have a few issues, but those will mostly deal with I/O. I'd recommend going through and replacing all the couts first. All your control structures will be the same, so I'm pretty sure you'll just need to do the cin/couts and the file IO. There might be a few other things that I'm missing on the spot-check, but those should get you down to a level where the errors in compilation will show you any of the others.

[optimum]

hi i tried to change the cout function to printf it can work perfectly, but when i use any stdin function's like scanf, i keep getting errors. I am also having trouble changing the stream functions. i have tried online tutorial's for the past 1 week but i am stuck in the scanf, and stream file functions. Please help me. Thank you

[sicarie]

hi i tried to change the cout function to printf it can work perfectly, but when i use any stdin function's like scanf, i keep getting errors. I am also having trouble changing the stream functions. i have tried online tutorial's for the past 1 week but i am stuck in the scanf, and stream file functions. Please help me. Thank you

Have you changed the libraries that handle those things? C and C++ use different headers...

[optimum]

Have you changed the libraries that handle those things? C and C++ use different headers...

I have changed the the header file to <stdio.h>, actually now my scanf function is working but i am not sure how to change some part of the coding to C language especially the file processing section. Below is my coding that i have have modify. Can you help in how to change the file processing/database part.
I am also having trouble with the switch case, after i have changed it to printf statement the case"2" is not working, but i think this is because i have not yet finish changing the whole coding. Am I right about this or is there anything when wrong when i convert the switch statement?

Thank you for your help

[

#include<fstream>
#include<string>
#include<iostream>
#include<iomanip>
#include<stdio.h>
using namespace std;
struct employee{   string fname, lname;
         double hourlyrate, hoursworked, netpay; 
}emp; //employee
employee e[100];
int n=0;
void load(){
    ifstream fin("employee.txt",ios::in);
    while(fin>>e[n].fname>>e[n].lname>>e[n].hourlyrate>>e[n].hoursworked){
    e[n].netpay=e[n].hourlyrate*e[n].hoursworked;
    n++;}//WHILE
    }//LOAD
void store(){
    ofstream fout("employee.txt",ios::out);
    for(int i=0; i<n; i++){
    if(e[i].fname!=" ")
    fout<<e[i].fname<<" "<<e[i].lname<<" "<<e[i].hourlyrate<<" "<<e[i].hoursworked<<endl;
}//FOR
    }//STORE
 
void insert(){
     printf("Enter employee's first name: ");
     scanf("s",& emp.fname);
     printf("Enter employee's last name: ");    
    scanf("s",& emp.lname);
     cout<<"Enter employee's salary per hour: ";     cin>>e[n].hourlyrate;
     if(cin.fail())
          {cout<<"Error\n"; exit(1);}
     cout<<"Enter employee's hours worked: ";
     cin>>e[n].hoursworked;
    e[n].netpay=e[n].hourlyrate*e[n].hoursworked;
    n++;    }//INSERTS THE RECORD TO ARRAY
 
void display(){
 
    cout<<setiosflags(ios::left)<<setw(15)<<"First Name"<<setw(15)<<"Last Name";
    cout<<setw(10)<<"Hourly Rate"<<setw(10)<<"HrsWorked"<<setw(10)<<"Net Pay";
     cout<<endl<<endl;
     cout<<setiosflags(ios::fixed|ios::showpoint|ios::left);
for(int i=0;i<n;i++){
     if(e[i].fname!=" "){        
cout<<setiosflags(ios::left)<<setw(15)<<e[i].fname<<setw(15)<<e[i].lname;
cout<<setprecision(2)<<setiosflags(ios::left)<<setw(10)<<e[i].hourlyrate;
     cout<<setw(10)<<e[i].hoursworked<<setw(10)<<e[i].netpay;
     cout<<resetiosflags(ios::left)<<endl;}//IF
    }//FOR
}//THIS FUNCTION DISPLAYS ALL RECORDS IN ARRAY
 
int search(string s){
    for(int i=0;i<n;i++)if(s==e[i].lname)return i;//FOR
     return -1;
    }//SEARCH BY NAME,-1 NOT FOUND
void update(){
     string searchn;
     cout<<"Enter the Last Name of the Employee to be modified: ";     cin>>searchn;
    int i=search(searchn); 
    if(i==-1) cout<<"EMPLOYEE NOT LISTED"<<endl;
    else{
     cout<<endl<<"Please enter the updated information."<<endl;
     cout<<"Enter employee's first name: ";     cin>>e[i].fname;
     cout<<"Enter employee's last name: ";     cin>>e[i].lname;
     cout<<"Enter employee's rate per hour: ";      cin>>e[i].hourlyrate;
     cout<<"Enter employee's hours worked: ";       cin>>e[i].hoursworked;
     e[i].netpay=(e[i].hourlyrate*e[i].hoursworked);}
    }//UPDATE
 
void deleterec(){
 string searchn;
 cout<<"Enter the Last Name of the Employee to delete: ";  cin>>searchn;
 int k=-1;
 for(int j=0; j<n;j++){
  if(searchn==e[j].lname)
     k=j;}
 if(k!=-1)
 { cout<<" Name: "<<e[k].fname<<" "<<e[k].lname<<endl;
   cout<<" Salary: "<<e[k].hourlyrate<<endl;
   cout<<" Hrs Worked: "<<e[k].hoursworked<<endl;
   cout<<" Net Pay: "<<e[k].netpay<<endl<<endl;}
     
 char ans;
 cout<<endl<<"Do you want to delete this record? (Y/N): ";
 cin>>ans;
 if(ans=='Y'||ans=='y'){
    e[k].fname=" ";}//IF
else cout<<"EMPLOYEE NOT FOUND";     }//DELETE
 
void report(){
 int i=0;
 double totalhrs=0.00, totalpay=0.00;
 for(i=0;i<n;i++){
 totalhrs+=e[i].hoursworked;
 totalpay+=e[i].netpay; }//FOR
 cout<<"Total number of employees: " <<n<<endl<<endl;
 cout<<"Total hours worked by all employees: "<<totalhrs<<endl<<endl;
 cout<<"Total pay of all employees: "<<totalpay<<endl<<endl;   }//REPORT
 
void deletefile(){
 int pword;
 cout<<"Enter your administrative password: ";  cin>>pword;
 if(pword==5438){
 ofstream record("employee.txt", ios::out);
 record<<endl;
 load();
 record.close();}
 else cout<<"Wrong password entered."<<endl; }//DELETE FILE
 
 void backupfile(){
  system("copy employee.txt backup.txt");
  cout<<endl<<"Back-up file has been made."<<endl;
}
 
void main(){
    load();
    char choice='0';
    while (choice!='e'&&choice!='E'){
    printf("\nPayroll Database\n\n");
    printf("1. Insert Employee Record and Compute Net Pay\n");
    printf("2. Display All Records\n");
    printf("3. Search Database\n");
    printf("4. Update Record\n");
    printf("5. Delete Record\n");
    printf("6. Generate Report\n");
    printf("7. Delete Database File\n");
    printf("8. Back-up Database File\n");
    printf("\nType e to exit\n\n");
    printf("Enter the number of your choice:\n");
    scanf("%c",&choice);
    switch (choice){
 
       case '1': insert(); break;
     case '2': display(); break;
     case '3': char s[100]; int index;
          cout<<"Enter the last name of the person you want: ";
          cin>>s;
          index=search(s);
        if(index!=-1) {
        cout<<"Name: "<<e[index].fname<<" "<<e[index].lname<<endl;
        cout<<"Hourly Rate: "<<e[index].hourlyrate<<endl;
                cout<<"Hrs Worked: "<<e[index].hoursworked<<endl;
                cout<<"Net Pay: "<<e[index].netpay<<endl<<endl;}//IF
        else cout<<"EMPLOYEE NOT FOUND"<<endl;
          break;
     case '4': update(); break;
     case '5': deleterec(); break;
     case '6': report(); break;
     case '7': deletefile(); break;
     case '8': backupfile(); break;
     case 'e': store(); break; //EXIT
     default: cout<<"Invalid Choice"<<endl; break; }//SWITCH
}//WHILE
}//MAIN
 

The bold section's are the part i am having problem to convert to C language. Sorry for the trouble.

[RRick]

There's another way to convert the C++ code to C and you don't have to get rid of the C++ objects. You do this by using the extern C declaration. This will allow the function signature to look like C, and be called like a C function, but the function internals are still C++. Try this link http://www.parashift.com/c++-faq-lit....html#faq-32.1 and refer to section 32.6.

There are a couple of caveats

• All the function parameters must be C style variables. No C++ objects (like string) are permitted.
• When you link your C program with these routines, you will have to explictly add the C++ libraries. One way around this problem is to use the C++ compiler to compile your C program. The C++ compiler knows where the C and C++ libraries reside and the C++ compiler is a "better" C compiler.

[optimum]

I am sorry, i am trying to convert this c++ coding to c without mixing both the language, please help with some idea in the bolded section's in my coding.

[RRick]

Most of your issues are with converting C++ print and file mechanisms to C.

Instead of opening a file with ofstream use fopen. Its parameters are almost the same as ofstream. Use "r" and "w" instead ios::in and out.

C style printf and fprintf are going to become very good friends. Their format is different from <<, but they have very good formating capabilities. Instead of setw, you can use "%15s" for printing a string with a width of 15, and "%-15s" reverses the justification. A google search will find the various options for (f)printf.

[optimum]

Can anyone give show me a example how to use my fopen in this part of my coding:

fout<<e[i].fname<<" "<<e[i].lname<<" "<<e[i].hourlyrate<<" "<<e[i].hoursworked<<endl;

How can i this part i am confused with the "::" parts:

cout<<setiosflags(ios::left)<<setw(15)<<"First Name"<<setw(15)<<"Last Name";
    cout<<setw(10)<<"Hourly Rate"<<setw(10)<<"HrsWorked"<<setw(10)<<"Net Pay";
    cout<<endl<<endl;
    cout<<setiosflags(ios::fixed|ios::showpoint|ios::left);
for(int i=0;i<n;i++){
    if(e[i].fname!=" "){      
cout<<setiosflags(ios::left)<<setw(15)<<e[i].fname<<setw(15)<<e[i].lname;
cout<<setprecision(2)<<setiosflags(ios::left)<<setw(10)<<e[i].hourlyrate;
    cout<<setw(10)<<e[i].hoursworked<<setw(10)<<e[i].netpay;
    cout<<resetiosflags(ios::left)<<endl;}//IF
    }//FOR

[RRick]

fout is used to print something, so you can't use fopen at that part of the program. Fopen is only used to "open" files, not print them.

Instead, you use fprintf. Your fout printing would translate into C as:

//  C++ print
fout<<e[i].fname<<" "<<e[i].lname<<" "<<e[i].hourlyrate<<" "<<e[i].hoursworked<<endl;
 
/*  C print  */
FILE * fhandle = fopen( ....);
fprintf( fhandle, "%s %s %d %d\n", e[i].fname, e[i].lname, e[i].hourlyrate, e[i].hoursworked);