Why am I getting segmentation fault on this?

This is a discussion on Why am I getting segmentation fault on this? within the C++ Programming forums, part of the General Programming Boards category; Hi I keep getting segmentation fault when the program gets to Code: c[i] = c[i + 1]; This is in ...

  1. #1
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    Why am I getting segmentation fault on this?

    Hi


    I keep getting segmentation fault when the program gets to

    Code:
    c[i] = c[i + 1];
    This is in another constructor, I have included the code and the output below, Please let me know if you know why I get segmentation fault when I use c[i] = c[i + 1]


    Code:
    #include <stdio.h>
    #include <string.h>
    
    class Account
    {
    char customer[251];
    char accountNumber[16];
    int balance;
    
    public:
    Account();
    Account(char c[]);
    };
    
    int main()
    {
    Account test("    test");
    
    return 0;
    }
    
    Account::Account()
    {
    strcpy(customer, ",,,;");
    strcpy(accountNumber, "000000000000000");
    balance = 0;
    }
    
    Account::Account(char c[])
    {
     int i = 0;
    
    
    //while loop removes the spaces in front of the string.
     while (c[i] == ' ' || c[i] == '\t' || c[i] == '\n')
     {
        printf("Loop started\n");
        c[i] = c[i + 1];
        i++;
     }
    
    }

    Output

    Loop started
    Segmentation fault

    Thank You

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    Because " test" is not a writable string. It's a string literal, and cannot be changed in memory.

  3. #3
    Frequently Quite Prolix dwks's Avatar
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    Canada
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    I think this is a buffer overflow, too.
    Code:
    strcpy(accountNumber, "000000000000000");
    BTW, isspace() from <cctypes> is your friend.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
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  4. #4
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    Quote Originally Posted by tabstop View Post
    Because " test" is not a writable string. It's a string literal, and cannot be changed in memory.
    But I'm trying to move characters in "char c[]" which is a character array, would you clarify this?

  5. #5
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    I think now I understand, first I have to copy the string into the data member than I can move the characters in the string.

  6. #6
    Guest Sebastiani's Avatar
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    Also:
    - Use std::strings, not character arrays. Otherwise, you will need to define a copy-constructor and assignment operator. Besides, it will make your life much easier.
    - Space-trimming is so common as to warrant being it's own function, outside of the class.
    Code:
    #include <cmath>
    #include <complex>
    bool euler_flip(bool value)
    {
        return std::pow
        (
            std::complex<float>(std::exp(1.0)), 
            std::complex<float>(0, 1) 
            * std::complex<float>(std::atan(1.0)
            *(1 << (value + 2)))
        ).real() < 0;
    }

  7. #7
    Cat without Hat CornedBee's Avatar
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    char[], when in a function parameter list, is only an alias for char*.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

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