Undeclared Identifier in my function call (C++) - c++

Question

I am a new programmer working in C++, I am trying to make a program that will import information from a file to an output file and then I'm going to do a search algorithm on the data. I am trying to use a structure of data and import that into an array and then call it in the main program.
For some reason I can't, for the life of me, get my function call to work; I keep getting an undeclared identifier error on inputFile in my function call in the main program. I realize I'm probably doing something fundamentally wrong, so I would really appreciate any help that can be given.
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib>
#include <fstream>
using namespace std;
const int MAX_LOG_SIZE = 7584;
const string LOGFILE ="crimes.dat";
const string OUTPUT_FILE ="crimesorted.log";
// Structure of strings based on info from crimes.dat
struct CrimeInfo
{
string Crimedescr;
string Date;
string Time;
string Address;
string Grid;
string Latitude;
string Longitude;
};
CrimeInfo crimeList [MAX_LOG_SIZE];
void openInputFile(ifstream& inputFile, string inputFilename)
// here we open the input file crimes.dat
{
inputFile.open(inputFilename.c_str());
while (inputFile.fail())
{
cout << "Failed to open input file: " << inputFilename << ".\n";
exit(1);
}
};
void getLogEntry(ifstream &LOGFILE, CrimeInfo &entry)
{
getline(LOGFILE, entry.Date);
getline(LOGFILE, entry.Time);
getline(LOGFILE, entry.Address);
getline(LOGFILE, entry.Grid);
getline(LOGFILE, entry.Crimedescr);
getline(LOGFILE, entry.Latitude);
getline(LOGFILE, entry.Longitude);
}
/* opens an output file */
void openOutputFile(ofstream& outputFile, string outputFilename)
{
outputFile.open(outputFilename.c_str());
if (outputFile.fail())
{
cout << "Failed to open output file: " << outputFilename << ".\n";
exit(2);
}
}
void outputLogFile(string outputFilename, CrimeInfo arr[], int size)
{
// open output files
ofstream outputLogFile;
openOutputFile(outputLogFile, outputFilename);
// output the crime file
outputLogFile << "\nCrime log sort ^^:\n\n";
for (int i = 0; i < size; i++)
{
outputLogFile << arr[i].Date << " ";
outputLogFile << arr[i].Address << " (";
outputLogFile << arr[i].Longitude << " ";
outputLogFile << arr[i].Latitude << " ";
outputLogFile << arr[i].Time << " ";
outputLogFile << arr[i].Grid << " ";
outputLogFile << arr[i].Crimedescr << "";
outputLogFile << endl;
}
outputLogFile.close();
}
int main()
{
outputLogFile(OUTPUT_FILE, crimeList, MAX_LOG_SIZE);
for (int i =0; i < MAX_LOG_SIZE; i++)
getLogEntry(inputFile, crimeList[i].Date);
}

Answer 1

There are a lot of problems with your code. To help you out, I went through your code and left a lot of my own comments to tell you some suggestions I had; to make it easy, I deleted your comments so there's no confusion on what was yours and what I put there.
Here are some things I noticed in your code:
using namespace std is generally considered a very bad practice. Instead, just specify the namespace (e.g. std::string instead of just string).
You declared LOGFILE as a string at the top of your program, but then tried to use it as an ifstream& in the function getLogEntry.
Your main method is out of order. I'm assuming you want to load some data into the program from a file and then output that data to another file. The way you have it in your main method is, first, you output information you don't have yet and, second, import information but don't do anything with it.
You have a LOT of functions. As a general rule of thumb, don't make a whole function for opening a file, then a separate one for using it, then a separate one for closing it. There are a lot of big reasons why not to do this. The biggest reasons are that your program becomes very difficult to follow, and no one else will be able to use your code. In real-world applications, your code is only 20% for the computer and 80% for other programmers.
There are various formatting errors and such.
So, here is your original code with my comments...
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib> // Unneeded since other headers here already include this
#include <fstream>
using namespace std; // NEVER globally use the entire standard namespace!
const int MAX_LOG_SIZE = 7584; // Can be declared 'constexpr'
const string LOGFILE ="crimes.dat";
const string OUTPUT_FILE ="crimesorted.log";
/*
NOTE:
> It often looks a lot cleaner to have a header part of your code
and then define your functions seperately. This is good practice
for when you need to start using header files with big projects
*/
struct CrimeInfo
{ // Can declare all variables by only listing type once if they're all the same type
string Crimedescr;
string Date;
string Time;
string Address;
string Grid;
string Latitude;
string Longitude;
};
CrimeInfo crimeList [MAX_LOG_SIZE]; // This should be in 'main()'
/*
This should not be its own function.
Making too many function can make things look a bit confusing.
Here, this is only 4 lines of code, so you shouldn't be making
an entire function for it.
*/
void openInputFile(ifstream& inputFile, string inputFilename)
{
inputFile.open(inputFilename.c_str());
while (inputFile.fail())
{
cout << "Failed to open input file: " << inputFilename << ".\n";
exit(1);
}
};
/*
This should also just be written out where its used. There's
no need to make a whole function for a task like this.
ERROR HERE:
> LOGFILE is NOT an std::ifstream! It is a std::string!
*/
void getLogEntry(ifstream &LOGFILE, CrimeInfo &entry)
{
getline(LOGFILE, entry.Date);
getline(LOGFILE, entry.Time);
getline(LOGFILE, entry.Address);
getline(LOGFILE, entry.Grid);
getline(LOGFILE, entry.Crimedescr);
getline(LOGFILE, entry.Latitude);
getline(LOGFILE, entry.Longitude);
}
/*
This should not be its own function.
Making too many function can make things look a bit confusing.
Here, this is only 4 lines of code, so you shouldn't be making
an entire function for it.
*/
void openOutputFile(ofstream& outputFile, string outputFilename)
{
outputFile.open(outputFilename.c_str());
if (outputFile.fail())
{
cout << "Failed to open output file: " << outputFilename << ".\n";
exit(2);
}
}
// It's a good idea to use some sort of documentation style for functions
void outputLogFile(
// Declare variables const when they aren't modified
/* (const) */ string outputFilename,
/* (const) */ CrimeInfo arr[],
/* (const) */ int size)
{
ofstream outputLogFile;
openOutputFile(outputLogFile, outputFilename); // Just write out the code
outputLogFile << "\nCrime log sort ^^:\n\n";
for (int i = 0; i < size; i++)
{
/*
You only need to declare the name of the stream one time
e.g.
outputLogFile << thing1 << thing2
<< thing3 << thing4 << thing5
<< thing6
<< endl;
*/
outputLogFile << arr[i].Date << " ";
outputLogFile << arr[i].Address << " (";
outputLogFile << arr[i].Longitude << " ";
outputLogFile << arr[i].Latitude << " ";
outputLogFile << arr[i].Time << " ";
outputLogFile << arr[i].Grid << " ";
outputLogFile << arr[i].Crimedescr << ""; // Empty quotes not needed here
outputLogFile << endl;
}
outputLogFile.close();
}
int main()
{
// What data are you outputting?
outputLogFile(OUTPUT_FILE, crimeList, MAX_LOG_SIZE);
// Are you trying to load the data you just outputted?
for (int i =0; i < MAX_LOG_SIZE; i++)
{ // I added these braces, but it's a good idea to always have braces
// You have not declared 'inputFile' anywhere
getLogEntry(inputFile, crimeList[i].Date);
}
}
Instead of leaving you to have to figure all that out on your own (I know how frustrating that can be), I went ahead and wrote your program how I'd do it. I tried to put comments in a lot of places to make it easy to follow along with. If you have any questions about it, feel free to ask me.
#include <fstream>
#include <iomanip>
#include <iostream>
#include <string>
/*
If you're using C++17, the lines below can just become one line:
using std::cin, std::cout, std::endl, std::ifstream,
std::ofstream, std::string, std::getline;
*/
using std::cin;
using std::cout;
using std::endl;
using std::ifstream;
using std::ofstream;
using std::string;
constexpr int MAX_LOG_SIZE = 7584;
const string LOGFILE_NAME = "crimes.dat";
// I'm assuming: inputFile ^^^
// outputFile vvv
const string OUTPUT_FILE_NAME = "crimesorted.log";
/*
NOTE: If you're trying to export data to "crimesorted.log"
and then load it back into the program through "crimes.dat",
that will be a problem. I say this because the main method
in your original code, this is the order you had it in.
*/
// [BEGIN] Function Prototypes
// Structure of strings based on info from crimes.dat
struct CrimeInfo
{
string Crimedescr, Date, Time, Address,
Grid, Latitude, Longitude;
};
/** (This is JavaDoc-style documentation)
[Purpose of function here]
#param outputFile [Describe paramater here]
#param arr[] [Describe parameter here]
#param size_of_arr Size of 'arr[]'
*/
void outputLogFile(
ofstream& outputFile, // Changed to 'std::ofstream&' because I declare this in 'main()'
const CrimeInfo arr[],
const int size_of_arr);
// [END] Function Prototypes
int main()
{
// Create std::ifstream and open a file
ifstream file_to_load;
file_to_load.open(LOGFILE_NAME);
// Constructing and using 'crimeList' here allows the size to be known in
// this scope. However, if it's passed to a function, it's passed as a pointer
CrimeInfo crimeList[MAX_LOG_SIZE];
// Check if file was open and do stuff with it
if (file_to_load.is_open())
{ // File was opened
for (int i = 0; i < MAX_LOG_SIZE; i++)
{
getline(file_to_load, crimeList[i].Date);
getline(file_to_load, crimeList[i].Time);
getline(file_to_load, crimeList[i].Address);
getline(file_to_load, crimeList[i].Grid);
getline(file_to_load, crimeList[i].Crimedescr);
getline(file_to_load, crimeList[i].Latitude);
getline(file_to_load, crimeList[i].Longitude);
}
file_to_load.close(); // Close file
}
else
{ // File could not be
cout << "Could not open file: " << LOGFILE_NAME << endl;
return 1;
}
// Create std::ofstream and output the log
ofstream outputFile;
outputFile.open(OUTPUT_FILE_NAME);
// Check if 'outputFile' opened OUTPUT_FILE_NAME successfully
if(outputFile.is_open())
{ // File was opened
outputLogFile(outputFile, crimeList, MAX_LOG_SIZE);
outputFile.close();
}
else
{ // File could not be opened
cout << "Could not open file: " << OUTPUT_FILE_NAME << endl;
return 1;
}
}
// Function definition for outputLogFile()
void outputLogFile(
ofstream &outputFile,
const CrimeInfo arr[],
const int size_of_arr)
{
outputFile << "\nCrime log sort ^^:\n\n";
for (int i = 0; i < size_of_arr; i++)
{
outputFile
<< arr[i].Date << '\n' // Newlines may look better than spaces here
<< arr[i].Address << " ("
<< arr[i].Longitude << ", "
<< arr[i].Latitude << ")\n"
<< arr[i].Time << '\n'
<< arr[i].Grid << '\n'
<< arr[i].Crimedescr
<< endl;
}
}