Return multiple values from a function.

[Torm04]

Hello, I seem to have hit a stump on my assignment... I need to pass multiple values from one function to another and need a little help on how to do this. Here is my code so far.

#include <iostream>
#include <string>
#include <cctype>
#include <fstream>
using namespace std;

//Function Prototypes//
int charString(string, string, string);
string reverseString(string, string, string);
//------------------//

int main()
{
	
}

string charString()
{
	ifstream inFile;

	// Holds the strings for each line.
	string line1;
	string line2; 
	string line3; 
	 // Holds the lenth of each of the lines.
	int length1 = 0; 
	int length2 = 0; 
	int length3 = 0;

	
	inFile.open("testdata.txt"); //Opens test .txt file
	//Gets the full string line.
	getline(inFile, line1);
	getline(inFile, line2);	
	getline(inFile, line3);

	//Gets the strings length.
	
    for(int i = 0; i < line1.length(); i++) //Determines isalpha string length for line 1
    {
    	if(isalpha(line1[i]))
    	{
    		length1++;
		}
	}
	 for(int i = 0; i < line2.length(); i++) //Determines isalpha string length for line 2
    {
    	if(isalpha(line2[i]))
    	{
    		length2++;
		}
	}
	 for(int i = 0; i < line3.length(); i++) //Determines isalpha string length for line 3
    {
    	if(isalpha(line3[i]))
    	{
    		length3++;
		}
	}
	cout << length1 << endl;
	cout << length2 << endl;
	cout << length3 << endl;
	
	return line1, line2, line3;
}

string reverseString() //Trying to pass the values from lines 1-3 here...
{
	
	cout << "Here is the String the correct way." << endl;
	cout << line1 << endl << line2 << endl << line3 << endl;
	cout << "Here is the String backwards." << endl;
	cout << "Nothing here yet :/" << endl;
	
}   

Thanks in advance for any help. I basically need to take line1, line2, and line3 and return them to the reverseString function.
Also, I am not allowed to do anything like make my own classes. I have to stick to the basics and no higher level programming techniques since we have not learned them yet.

[keskiverto]

Who wrote the function prototypes?

[MiiNiPaa]

You did pass of three values correctly in prototype on line 9. You just need to make definition on line 67 match it.

[Torm04]

What do you mean who wrote the prototypes?

And thanks MiiNiPaa, how exactly would that look on line 67?

[MiiNiPaa]

What do you mean who wrote the prototypes?

He is asking why line 9 and 67 are different and why you wrote it like that?

[tipaye]

Prototypes: Your function declaration MUST match the definition. Lines 8 and 9 must match lines 17 and 67 respectively.

At present they don't match, you have:

8: int charString(string, string, string);
17: string charString()

9: string reverseString(string, string, string);
67: string reverseString()

In line 64 :

return line1, line2, line3;

This is illegal, you can only return one thing from a function.

Finally, I'm not sure what you're trying to accomplish, so I can't comment on the correctness of the solution, but here's your code with some small changes I believe are in keeping with your question and comments.

#include <iostream>
#include <string>
#include <cctype>
#include <fstream>

using namespace std;

//Function Prototypes//
void charString(string &, string &, string &);
void reverseString(string &, string &, string &);
void is_alpha_length(const string& line, int &length);
//------------------//

int main()
{
	string x, y, z;
	charString(x, y, z);
	reverseString(x, y, z);
}

// line1, line2 and line3 are passed by reference, so they'll be changed in  the function and you don't need to return anything
void charString(string &line1, string &line2, string &line3 ) 
{
	ifstream inFile;

    // Holds the length of each of the lines.
	int length1 = 0; 
	int length2 = 0; 
	int length3 = 0;

	
	inFile.open("testdata.txt"); //Opens test .txt file
	//Gets the full string line.
	getline(inFile, line1);
	getline(inFile, line2);	
	getline(inFile, line3);
	inFile.close(); // unless you still need it...

	//Gets the strings length.
	
	// use a function instead of repeating the same code thrice
	is_alpha_length(line1, length1);
	is_alpha_length(line2, length2);
	is_alpha_length(line3, length3);
	cout << length1 << endl;
	cout << length2 << endl;
	cout << length3 << endl;
}

void reverseString(string &line1, string &line2, string &line3) //Trying to pass the values from lines 1-3 here...
{
	
	cout << "Here is the String the correct way." << endl;
	cout << line1 << endl << line2 << endl << line3 << endl;
	cout << "Here is the String backwards." << endl;
	cout << "Nothing here yet :/" << endl;
	
}   

// original loop:
//for(int i = 0; i < line1.length(); i++) //Determines isalpha string length for line 1
//{
//	if(isalpha(line1[i]))
//	{
//		length1++;
//	}
//}

inline void is_alpha_length(const string& line, int &length)
{
        // a simpler way for this kind of loop
	for (auto i : line) if (isalpha(i)) ++length;
}

[Torm04]

That makes sense tipaye, thank you for your help.