Help needed

This is a discussion on Help needed within the C Programming forums, part of the General Programming Boards category; I am writing a program that will call the unix execv program based on some of the command line arguments ...

  1. #1
    Registered User
    Join Date
    Oct 2005
    Posts
    1

    Help needed

    I am writing a program that will call the unix execv program based on some of the command line arguments passed to the program, so basically I need to make an argv[] for the execv call out of the argv[] that is passed to the program. Here is how I'm doing this

    Code:
    char **programArguments;
    
      for(j = 0, i = 4; i < argc; i++, j++)
        {
          printf("Entered\n");
          programArguments[j]=  argv[i];
          printf("Exited\n");
        }
    When I compile this with both gcc and borland on my windows platform, this section of code works perfectly fine, however, when compiling using gcc on my schools unix computer, this program crashes after the first "entered" is printed with a segmentation fault. Does anyone know what the problem is here and how to fix it?

  2. #2
    Code Goddess Prelude's Avatar
    Join Date
    Sep 2001
    Posts
    9,796
    The problem is that programArguments doesn't point to memory that you own. Repeat after me: Arrays and pointers are not the same.
    My best code is written with the delete key.

  3. #3
    Registered User
    Join Date
    Aug 2005
    Posts
    1,267
    try this
    Code:
    char *programArguments[5]; 
    
      for(j = 0, i = 4; i < argc; i++, j++)
        {
          printf("Entered\n");
          programArguments[j]=  argv[i];
          printf("Exited\n");
        }

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