Fixing Segmentation Faults in C++

Fixing Segmentation faults in C++

1. Compile your application with -g, then you'll have debug symbols in the binary file.

2. Use gdb to open the gdb console.

3. Use file and pass it your application's binary file in the console.

4. Use run and pass in any arguments your application needs to start.

5. Do something to cause a Segmentation Fault.

6. Type bt in the gdb console to get a stack trace of the Segmentation Fault.

How to fix segmentation error in C programming?

Looking at the actual code from your github link, then you have this:

strcpy(filename, ".txt");

if ((fptr = fopen(filename, "r")) == NULL)
{
  printf("Error! the entry doesn't exist");
}

fgets(message, 100, fptr);

First of all the strcpy is nonsense since it overwrites the filename and replaces it with ".txt". Since that is never a valid file name, fopen will always fail. And when it fails, you print an error message but continue execution, so the next fgets call will cause the crash.

Fix this by allocating enough space for filename, replace strcpy (overwrite) with strcat (append) and do a return etc upon failing to open the file.

You could easily have found these bugs yourself by single-stepping through the function using a debugger.

What exact is segmentation fault when using Stack and how to fix it?

When the stack is empty and you try .top() or .pop() then it will give segmentation fault (error caused by accessing memory ).

string s;
   cin >> s;
   int score = 0;
   stack<int> st;
   for (int i = 0; i < s.size(); i++){
     char a = s[i];
     if (a == '('){
       st.push(score);
       score = 0;
     }
     else if(!st.empty()){
       score = st.top() + max(score*2, 1);
       st.pop();
     }
   }
   cout << score;
}

How to fix the Segmentation fault (core dumped) in C++?

Here:

vector<int> nums1, nums2;

for(int i=0; i<m; i++) cin >> nums1[i]; // this causes undefined behavior
for(int i=0; i<n; i++) cin >> nums2[i]; // also this one

your vectors have no buffer to store data so you need to do this before using operator[]:

vector<int> nums1(m), nums2(n);

nums1.push_back(2); // will add 2 to the back of nums1 so size will become m + 1
nums2.push_back(6); // will add 6 to the back of nums2 so size will become n + 1

// you can do as many push_backs as you want until
// your computer runs out of memory

Now both will be initialized with m and n number of elements respectively.

If you used the at function instead of [], the program would throw a std::out_of_range exception and you would suddenly notice that you were trying to go out of bounds. But of course at comes at a performance cost.

How can i fix segmentation fault in my code and what is the process I should follow to fix this in the future?

You don't show us these "past functions", but I assume that they ask the user for name or owner. These elements of your struct are arrays, and if you pass their name as an argument it decays to a pointer to the first element.

In contrast, the integer is not an array. Therefore, you need to pass its address like this:

    if (command[0] == 's') {
        get_integer_input(&the_pizzeria->selected_order, "");
    }

If you are not very firm with operator precedence, better use parentheses:

    if (command[0] == 's') {
        get_integer_input(&(the_pizzeria->selected_order), "");
    }

The compiler is correct with its diagnostic message. You pass an integer, but the functions needs a pointer.

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