Thread: difference between char *prt and char prt

  1. #1
    Registered User
    Join Date
    May 2009

    difference between char *prt and char prt

    Hi All

    is there a difference between

    char *prt = "hello"

    char prt[] = "hello"
    I noticed because I got a 'Bus error' when I do

    #include <string.h>
    #include <stdlib.h>
    #include <stdio.h>
      char *prt = "abc=def" ;
      char *out = strtok(prt, "=") ;
    but it works when I use ptr[]!


  2. #2
    spurious conceit MK27's Avatar
    Join Date
    Jul 2008
    segmentation fault
    The first one (char *ptr) is a "const" string literal, which means it cannot (or should not) be changed.

    The second one (char ptr[]) is a character array, initialized with a value, but the value *can* be changed.

    The reason you get an error using strtok() on a const is because strtok() actually destroys the string you are processing in the process. You will see what happens if you add a printf() after strtok() to show the string. Other functions, like sscanf, strcmp, and strstr do not alter the string analysed, so it is not a problem. strtok() is fine with "normal" strings, ie, character arrays.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
    Registered User
    Join Date
    May 2009
    ok, thnx a lot!!

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