Read all the lines C++

[CookieMaster]

Hello, so first off my code works. My only problem is that it reads the first line only. The file type is an .asc. My code is down bellow, what do I have to do to make it read the entire document?

 

#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>

using namespace std;

int main()
{
	int response;
	string filename = "cookies"; // Change this if image file name is different.
	string type = ".asc"; // Change this if file type is different.
	string img; /

	cout << "Welcome to Tx Paint (Tunxis Paint)" << endl;
	cout << "[1] Load image" << endl;
	cout << "[2] Draw line in image" << endl;
	cout << "[3] Draw box in image" << endl;
	cout << "[4] Save image" << endl;
	cout << "[5] Exit" << endl;
	cin >> response; 

	if (response == 1)

	{
		ifstream File((filename + type).c_str()); // Load file and file type stated above.
		if (File.is_open())
		getline(File, img); 
		File.close();
		cout << img << endl; // Display the image.
		system("pause"); 
		//Todo: add array.
	}

    return 0;
}

 

[TheKDub]

I'm not too familiar with C++, though have used Java and VB.Net plenty, so I'll give it a go...

 

I'd guess it's because you're only getting a single line, and not running a loop checking for if there's a next line, then reading that line. (Or at least from what I can tell there isn't one)

[CookieMaster]

1 minute ago, TheKDub said:

I'm not too familiar with C++, though have used Java and VB.Net plenty, so I'll give it a go...

 

I'd guess it's because you're only getting a single line, and not running a loop checking for if there's a next line, then reading that line. (Or at least from what I can tell there isn't one)

Yeah true. I guess my question is more of a how to, but I will keep looking and trying and seeing if I can figure it out. Thanks for the advice as well.

[TheKDub]

Just now, CookieMaster said:

Yeah true. I guess my question is more of a how to, but I will keep looking and trying and seeing if I can figure it out. Thanks for the advice as well.

I'm not familiar enough with C++ file handling to be able to help much there, though the basic idea of it would just be something like a while loop checking to see if there's another line in the file to be read, then reading that line within the loop.

[CookieMaster]

Figured it out 

{
		ifstream File((filename + type).c_str()); // Load file and file type stated above.
		while (getline(File, img))
		cout << img << endl; // Display the image.
		system("pause"); // Don't exit application
		//Todo: add array.
	}

 

26 minutes ago, TheKDub said:

I'm not familiar enough with C++ file handling to be able to help much there, though the basic idea of it would just be something like a while loop checking to see if there's another line in the file to be read, then reading that line within the loop.

Thanks again. While was just needed and then got rid of closing the file. 

[Unimportant]

6 hours ago, CookieMaster said:

Figured it out 

{
		ifstream File((filename + type).c_str()); // Load file and file type stated above.
		while (getline(File, img))
		cout << img << endl; // Display the image.
		system("pause"); // Don't exit application
		//Todo: add array.
	}

 

Thanks again. While was just needed and then got rid of closing the file. 

Some finer points:

 

Since C++11, ifstream's contructor has an overload that takes a std::string as filename, so you no longer need "c_str":

		ifstream File(filename + type); 

Put braces around every conditional block, even if it contains only 1 line, otherwise you'll quickly start making errors when changing the code afterwards, it's also confusing to read without the braces/proper indentation. 

		while (getline(File, img))
		{
			cout << img << '\n';
		}

Also note the endl was changed to '\n'. std::endl is more then simply a newline, it also flushes the output buffer, which can be expensive when done in a loop like it is here, it kinda defeats the purpose of having a buffer in the first place.

[stmfd sp!, {lr}]

As a small side note, don't ever use system("pause"); as it's not platform independent. Use std::cin's ignore facility to block the program and then discard whatever is entered.

[CookieMaster]

11 hours ago, Unimportant said:

Some finer points:

 

Since C++11, ifstream's contructor has an overload that takes a std::string as filename, so you no longer need "c_str":

		ifstream File(filename + type); 

Put braces around every conditional block, even if it contains only 1 line, otherwise you'll quickly start making errors when changing the code afterwards, it's also confusing to read without the braces/proper indentation. 

		while (getline(File, img))
		{
			cout << img << '\n';
		}

Also note the endl was changed to '\n'. std::endl is more then simply a newline, it also flushes the output buffer, which can be expensive when done in a loop like it is here, it kinda defeats the purpose of having a buffer in the first place.

Thanks on those pointers. 

 

24 minutes ago, stmfd sp!, {lr} said:

As a small side note, don't ever use system("pause"); as it's not platform independent. Use std::cin's ignore facility to block the program and then discard whatever is entered.

So what would I add to the end to make it not exit automatically? 

[stmfd sp!, {lr}]

2 minutes ago, CookieMaster said:

So what would I add to the end to make it not exit automatically? 

Something along the lines of like:

std::cin.ignore(); does the trick.