Segmentation fault reading string on cin read

Click For Summary

Discussion Overview

The discussion revolves around a programming issue related to reading a string from standard input using cin in C++. Participants are exploring the cause of a segmentation fault that occurs when attempting to read input from a file named "data4nine". The scope includes debugging, memory access violations, and proper handling of input data.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes encountering a segmentation fault when executing "cin >> strWord" and expresses uncertainty about the nature of the error.
  • Another participant explains that a segmentation fault typically indicates a memory access violation, suggesting that the issue may stem from accessing a part of a string that does not exist.
  • A different participant notes that access violations can occur due to either dereferencing a null pointer or indexing an array out of bounds, advising the original poster to check their loop definitions to ensure they do not exceed string bounds.
  • The original poster later confirms that they checked their loops and resolved the issues, thanking the participants for their help.
  • Another participant warns that using an input of just one word or no input at all may lead to unexpected results, indicating potential further issues with input handling.

Areas of Agreement / Disagreement

Participants generally agree on the nature of segmentation faults and the importance of proper indexing, but the discussion does not reach a consensus on all aspects of input handling and potential edge cases.

Contextual Notes

Limitations include the original poster's lack of clarity on the specific cause of the segmentation fault and the potential for unexpected results with certain types of input, which remain unresolved.

OSalcido
Messages
66
Reaction score
0

Homework Statement


I'm trying to read a string from cin. When it hits the "cin >> strWord" statement, I get the following error message: Segementation fault (core dumped). The input file is named "data4nine". I'm really not sure what a segmentation fault is and why I'm getting it


The Attempt at a Solution


Code:
	while (!cin.eof())
	{
		cin >> strWord;
		intWords++;
		cntVowsCons(strWord, intVowels, intConsonants);
		strFormatted = FormatWord(strWord);
		lenWords += strWord.length();
		lenFormatted += strFormatted.length();


		if(strFormatted.length() % 2 != 0) 
			SwapMidChar(strFormatted);
		if(istenth(intWords, tenth))
			cout << strFormatted << endl;
		else
			cout << strFormatted;
		
	}
 
Physics news on Phys.org
Here are my files
 

Attachments

Segmentation fault is generally a memory access violation. In this case, your program will attempt to access part of a string that doesn't exist (I know where this is in your code, but it should be left as an exercise to you). You may attempt to find it by scrutinizing your code or by using a debugger.
 
Hi OSalcido! :smile:

When an access violation (aka segmentation violation) occurs in a program, it may or may not crash with a core dump.
And if it does crash, it's often not a the point where the access violation occurred.

In any program an access violation always occurs in one of 2 forms.

Either you follow a pointer that does not point anywhere.
Since you're not using pointers, that won't be a problem.

Or you are indexing an array outside of its bounds.
Each of your for-loops should be defined such that you can always be sure your string is indexed inside its bounds.
Can you check if that is the case?
 
Yes! Thank you guys I did check the loops and fixed the issues. Thanks a bunch
 
Your welcome. ;)

Btw, if you use an input of just one word and a newline, or none at all, you may get some results you don't expect.
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 24 ·
Replies
24
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
6K
  • · Replies 5 ·
Replies
5
Views
4K
  • · Replies 11 ·
Replies
11
Views
3K
  • · Replies 13 ·
Replies
13
Views
2K