Thread: string conversion to char*

  1. #1
    Registered User
    Join Date
    Feb 2003

    string conversion to char*

    Anybody have any idea how to convert strings to char*. I am writing a program that involves using some of the unix system calls (execv()) and I get input from the user with strings, but these functions take char* as parameters!!!


  2. #2
    Skunkmeister Stoned_Coder's Avatar
    Join Date
    Aug 2001
    std::string has a member function c_str() that returns a const char* rep of the string object.
    Free the weed!! Class B to class C is not good enough!!
    And the FAQ is here :-

  3. #3
    Registered User
    Join Date
    Nov 2001
    One solution is strcpy() and c_str() as the other member has mentioned.


  4. #4
    all my attempts of using c_str() have ended in an unhandled exception

    and the problem with the execv() call is that my input from the user is put into an array argv[] the call would be

    execv(argv[0], argv, 0);

    making the second parameter argv.c_str() gives me errors as well.

  5. #5
    Registered User rmullen3's Avatar
    Join Date
    Nov 2001


    Where's the string object?


    std::string a;

    The command line arguments aren't string objects
    "He who makes a beast of himself, gets rid of the pain of being a man." Dr. Johnson

  6. #6
    string buffer;
    string argv[10];

    cout << "enter agruments: ";
    getline.(cin, buffer);

    buffer gets split up into argv, for example if buffer was:
    /bin/ls -alg
    argv[0] = /bin/ls
    argv[1] = -alg

    then I want to call exec using those as parameters
    but I can't write
    execv(argv[0].c_str(), argv.c_str(), (char*)0);

    because I get errors for the argv.c_str()

  7. #7
    Registered User rmullen3's Avatar
    Join Date
    Nov 2001


    execv(argv[0].c_str(), argv.c_str(), (char*)0);

    you're not indexing an element of argv. Also, what you're doing still makes no sense = | You're trying to command line stuff, right? But you're declaring argv as an array of string objects.

    "He who makes a beast of himself, gets rid of the pain of being a man." Dr. Johnson

  8. #8
    End Of Line Hammer's Avatar
    Join Date
    Apr 2002
    There's a execv() example on this page.

    The version of execv() I've seen only take two parameters, with argv one being a vector, with a null terminating element (hence the name execv). Maybe you're confusing this function with execl(). Both are documented here.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

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