Thread: Converting string to unsigned long

  1. #1
    Registered User
    Join Date
    Jul 2007

    Converting string to unsigned long

    I'm passing a memory address as arguments to a program but when I try and convert the string to an unsigned long, I don't get anything.

    int main(int argc,char *argv[])
       unsigned long address = strtoul(argv[1])
       printf("Address: %ul\n",address);
    It just prints out a 0. The address I tried passing was bfffffff.

    Can I not pass hex values as arguments?

  2. #2
    Registered User
    Join Date
    Sep 2004
    First of all, strtoul() takes 3 arguments. Secondly, the format specifier for unsigned long is %lu, not %ul. Try this:

    #include <stdio.h>
    #include <stdlib.h>
    int main(int argc, char *argv[])
       unsigned long address = strtoul(argv[1], NULL, 0);
       printf("Address: %lu\n",address);
       return EXIT_SUCCESS;
    If the value you are passing is hex, pass it as "0xbfffffff", or change the last parameter to strtoul() to 16 (then you can leave off the preceding 0x).

  3. #3
    Registered User
    Join Date
    Jul 2007
    thanks, that helped!

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