Function errors using C++ in Visual Studio 2013

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People are mentioning that my question isn't clear enough so hopefully to make it easier for everyone I'm going to restructure it.

The code below is designed to print a function that creates an arrow made out of '*' for example:
1.__*
2._* * *
3.* * * * *
4.__ *
5.__ *
6.__ *

However, my arrow must be calculated from user input. The arguments of the arrow must take: The width of the arrow head, the width of the tail, length of the arrow from tail to point and the character used to draw the arrow (in this case '*')

Please take a look at the code, and then below I will post the errors I'm receiving when I try entering debug mode. I will update the code as I go along with peoples advice. Also please note I'm not an expert with C++, this is really my first task. So if you could please spell everything out for me as you would want it explained when you were a beginner. Thank you

C++

// program to run an arrow function
// Author: Douglas Tyler
// Date: 30.10.2014
// Edited: 06.11.2014

#include <iostream> 
#include <sstream> 
using namespace std;


void draw_arrow(int width, int tail, int length, char draw){

	for (int i = 1; i <= width; i += 2){ //print Head width

			for (int j = 0; j<(width - i) / 2; j++) //print Tail width
				std::cout << " "; // print space

			for (int j = 0; j<(length - i) / 2; j++); // print length
			std::cout << " "; // print space

		for (int j = 0; j			std::cout << draw;

		std::cout << "\n";
	}
	//print tail 
	for (int i = 0; i < width / 2; i++){
		for (int j = 0; j<(width - tail) / 2; j++)
			std::cout << " ";
		for (int j = 0; j<tail;>			std::cout << draw;
		std::cout << std::endl;
	}


}

int main() // main function
{
	cout << "Welcome to printArrow" << endl;
	cin >> " " >> endl;

	int width_of_arrow = 0;
	int width_of_tail = -1;
	int length_of_arrow = 0;
	char drawing_char = '\0';
	std::string input;
	std::cout << "Please input the Width of the Arrow head: "; // ask the user to input arrow head width information
	std::getline(std::cin, input);
	std::stringstream(input) >> width_of_arrow;

	std::cout << "Please input the Width of the Tail: 1";
	std::getline(std::cin, input);
	std::stringstream(input) >> width_of_tail;
	if (width_of_tail == -1) width_of_tail = 1;

	std::cout << "Please input the length of the Arrow: ";
	std::getline(std::cin, input);
	std::stringstream(input) >> length_of_arrow;
	if (length_of_arrow == -2) length_of_tail = 2;

	std::cout << "Input Drawing Character: *";
	std::getline(std::cin, input);
	drawing_char = input[0];
	if (drawing_char == '\0') drawing_char = '*';

	draw_arrow(width_of_arrow, width_of_tail, length_of_arrow, drawing_char);
	return 0;
}

Error 1 error C2086: 'std::string input' : redefinition
Error 2 error C2065: 'length_of_arrow' : undeclared identifier
Error 3 error C2065: 'length_of_arrow' : undeclared identifier
Error 4 error C2065: 'length_of_arrow' : undeclared identifier
Error 5 IntelliSense: identifier "length_of_arrow" is undefined"

This may seem simple to some of you but it isn't to me so I appreciate you being understanding. Thank you for any help you can give

Posted 7-Nov-14 4:00am

Member 11206644

Updated 7-Nov-14 4:57am

v7

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Comments

Nelek 7-Nov-14 13:07pm

You have deleted something important in your first "print tail" for

Have a look and review / correct your code. As it is (v7), it can't compile

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PIEBALDconsult · Answer 1 · 2014-11-07T04:13:00

Solution 2

C++

      void draw_arrow(int width, int tail, char draw, int length){
Line 62:   draw_arrow(width_of_arrow, width_of_tail, drawing_char);

Seems obvious to me.

Posted 7-Nov-14 4:13am

PIEBALDconsult

Comments

Member 11206644 7-Nov-14 10:15am

Ah yes, of course. Thank you for pointing that out. However I've changed it and I'm still getting the same thing :(

PIEBALDconsult 7-Nov-14 10:19am

Then update the queestion with the new code.

Richard MacCutchan · Answer 2 · 2014-11-07T05:15:00

Solution 4

Here is your code with all the irrelevant parts removed so it will build. You need to check carefully the logic of the draw_arrow function to make it work. There were two statements (marked) which were incomplete so they need correcting. Note, if you include a using namespace std; statement then you do not need to add the std:: prefix to all your STL statements.

C++

// program to run an arrow function
// Author: Douglas Tyler
// Date: 30.10.2014
// Edited: 06.11.2014

#include <iostream> 

using namespace std;
 

void draw_arrow(int width, int tail, int length, char draw)
{

	for (int i = 1; i <= width; i += 2)
	{
		//print Head width

		for (int j = 0; j < (width - i) / 2; j++) //print Tail width
			cout << " "; // print space

		for (int j = 0; j < (length - i) / 2; j++) // print length
			cout << " "; // print space

		for (int j = 0; j < (width - i) / 2; j++) // not sure what you want here			
			cout << draw;

		cout << endl;
	}
	//print tail 
	for (int i = 0; i < width / 2; i++)
	{
		for (int j = 0; j < (width - tail) / 2; j++)
			cout << " ";
		for (int j = 0; j < tail;) // not sure about this either
			cout << draw;
		cout << endl;
	}

}
 
int main() // main function
{
 
	int width_of_arrow = 0;
	int width_of_tail = -1;
	int length_of_arrow = 0;
	char drawing_char = '\0';


	cout << "Welcome to printArrow" << endl;
	cout << "Please input the Width of the Arrow head: "; // ask the user to input arrow head width information
	cin >> width_of_arrow;
 
	std::cout << "Please input the Width of the Tail: 1 ";
	cin >> width_of_tail;
	if (width_of_tail == -1)
		width_of_tail = 1;
 
	cout << "Please input the length of the Arrow: 2 ";
	cin >> length_of_arrow;
	if (length_of_arrow == -2)
		length_of_arrow = 2;
 
	cout << "Input Drawing Character: * ";
	cin >> drawing_char;
	if (drawing_char == '\0')
		drawing_char = '*';
 
	draw_arrow(width_of_arrow, width_of_tail, length_of_arrow, drawing_char);
	return 0;
}
</iostream>

Posted 7-Nov-14 5:15am

Richard MacCutchan

Comments

Member 11206644 7-Nov-14 11:27am

Thank you very much. That's very helpful. In the marked parts I have to say it's a combination of tutorial work and bad calculation by me by the looks of it. I would like there to calculate all four arguments including the head width, the tail width, the length from point to tail and the character used (in this case '*') and I'm not too sure how to go about that.

Richard MacCutchan 7-Nov-14 11:35am

The way to deal with problems like this is to start at the right point. Do not start by writing code in the hope that it will somehow come out right. Draw a sample arrow on paper, something like:


___*
__***
_*****
___*
___*
___*

(Underscore characters represent spaces)
Now you can figure out how many spaces, and stars are required on each line, and how those numbers relate to your input values. From that information you can figure out the calculation required for each part. Only then should you start writing the code.

Member 11206644 7-Nov-14 11:52am

Okay, perfect. I've drawn the right side of the arrow and labelled each argument required. I'm not quite sure how to implement a calculation for it though

Richard MacCutchan 7-Nov-14 11:59am

Look carefully at the numbers for each line; write them down alongside each line and look for the pattern.

For example, the arrow is 5 wide, and in the first line we print only one character. That means (5-1) will be spaces. Since we do not need the spaces after the star then we need to print (5-1)/2 spaces first, then the single star. On the next line we need 3 stars so it is (5-3)/2 spaces, and so on, until we print the full width of the arrow head.

Next the tail, which is a fixed width, so we only need the calculation once, and then repeat the printing of that number of spaces and stars until we reach the limit of the length.

Member 11206644 7-Nov-14 12:07pm

Would I need to code each line individually?

Richard MacCutchan 7-Nov-14 12:17pm

No, as I said before you need to use these values to figure out an algorithm. For example what is the sequence of values when printing the arrow head? The numbers follow a pattern so you can use a loop that builds that pattern by a simple calculation each time round the loop.

Member 11206644 7-Nov-14 12:26pm

For the example you gave would it be (for the head width) 5-1, 5-3, 5-5?

Richard MacCutchan 7-Nov-14 12:27pm

Much more from me and I will be doing all your work. Give it a try and see what happens, try some different values to ensure that your algorithm is correct, and note any errors.

Member 11206644 7-Nov-14 12:32pm

I appreciate all your contribution but hardly, I still am not very experienced writing in C++ so writing an algorithm in C++ is something else. But I'm sure there are many tutorials online, so thank you again for your help :)

Richard MacCutchan 7-Nov-14 12:36pm

An algortithm is just a set of instructions to solve some problem. Write it first in natural language as a series of steps, and then convert those instructions into code. The key here is that you start thinking in terms of the problem: inputs and outputs, and instructions required to transform one to the other. Converting those instructions into code will become easier as you gain experience.

Member 11206644 7-Nov-14 12:45pm

You don't need to tell me how to fix it if you feel you're doing too much already, but could you tell me yes or no whether this could work or not to print the head width?

{
int i; // print head width
for (i = 0; i < 5; i++)
cout << " "; // print space
}

Richard MacCutchan 7-Nov-14 12:56pm

That won't do anything, since all you are doing is printing spaces.

You are still trying to write code without working out first what steps are required. Go back to the arrow picture and look again at the numbers. The first line (stars = 1) requires (width - stars)/2 spaces, followed by stars '*' characters. The next line (stars = 3) ... so the stars count increases by 2 for each line until it reaches the value specified by width.

I cannot repeat it enough: think about the values on each line and write down the calculations required for each. You can then figure out what needs to change in each step, e.g the 'stars' value needs to increment by 2 each time. The second important point is that you need to keep testing things yourself. Instead of asking questions such as "will this work?", try it for yourself and learn from the experience.

Member 11206644 7-Nov-14 14:12pm

This seems like such a complicated task for a beginner. I've only got as far as working out that I need the algorithm to not exceed the user input and increase by 2 each line. I've already written everything out but to convert this to code seems massively complicated because it's all calculations

Richard MacCutchan 7-Nov-14 15:54pm

I am not sure what you find complicated, I have even shown you the calculations you need.

The first loop starts at 1, increments by 2 until it reaches some value. A couple of simple calculations within each iteration of the loop (which I gave you). A second calculation before a loop starts, the loop repeating for a fixed number of iterations.

Member 11206644 10-Nov-14 9:48am

Thanks for all your help mate. I got there in the end!

Richard MacCutchan 10-Nov-14 10:04am

Well done.