How to Initialize char array from a string

Question

I want to do the following  char a        A    B    C    D      But I do not want to write these characters separately  I want something like   define S  ABCD   char a       S 0   S 1   S 2   S 3       But this won t compile  gcc says  initializer element is not constant     I tried replacing the  define line with  const char S      ABCD     But that doesn t seem to help   How can I do this  or something similar  that lets me write the  ABCD  as a normal  string   and not as four separate characters   P S  It seems that people do not read the question correctly     I can t get the following code to compile   const char S      ABCD   char t       S 0   S 1   S 2   S 3     char u       S 3   S 2   S 1   S 0

User · Answer

I m not sure what your problem is  but the following seems to work OK    include  lt stdio h gt   int main         const char s0      ABCD       const char s1       s0 3   s0 2   s0 1   s0 0   0         puts s0       puts s1       return 0      Microsoft  R  32-bit C C   Optimizing Compiler Version 13 10 3077 for 80x86 Copyright  C  Microsoft Corporation 1984-2002  All rights reserved  cl  Od  D  WIN32   D   CONSOLE   Gm  EHsc  RTC1  MLd  W3  c  ZI  TC      Tmp c Tmp c Linking     Build Time 0 02   C  Tmp gt tmp exe ABCD DCBA  C  Tmp gt    Edit 9 June 2009  If you need global access  you might need something ugly like this    include  lt stdio h gt   const char  GetString int bMunged        static char s0 5     ABCD       static char s1 5        if  bMunged            if   s1 0                  s1 0    s0 3                s1 1    s0 2               s1 2    s0 1               s1 3    s0 0               s1 4    0                    return s1        else           return s0            define S0 GetString 0   define S1 GetString 1   int main         puts S0       puts S1       return 0

User · Answer

This compiles fine on gcc version 4 3 3  Ubuntu 4 3 3-5ubuntu4    const char s      cheese    int main         return 0

User · Answer

The compilation problem only occurs for me  gcc 4 3  ubuntu 8 10  if the three variables are global  The problem is that C doesn t work like a script languages  so you cannot take for granted that the initialization of u and t occur after the one of s  That s why you get a compilation error  Now  you cannot initialize t and y they way you did it before  that s why you will need a char   The code that do the work is the following    include  lt stdio h gt   include  lt stdlib h gt    define STR  ABCD   const char s     STR  char  t  char  u   void init        t   malloc sizeof STR -1       t 0    s 0       t 1    s 1       t 2    s 2       t 3    s 3         u   malloc sizeof STR -1       u 0    s 3       u 1    s 2       u 2    s 1       u 3    s 0      int main void        init        puts t       puts u        return EXIT SUCCESS

User · Answer

Simply  const char S      ABCD     should work   What s your compiler

User · Answer

Weird error   Can you test this   const char  const S    ABCD   char t       S 0   S 1   S 2   S 3     char u       S 3   S 2   S 1   S 0

User · Answer

Perhaps your character array needs to be constant   Since you re initializing your array with characters from a constant string  your array needs to be constant   Try this    define S  ABCD  const char a       S 0   S 1   S 2   S 3

User · Answer

That s one of the cases a script to generate the appropriate code might help

User · Answer

const char S      ABCD     This should work  i use this notation only and it works perfectly fine for me  I don t know how you are using

User · Answer

Another option is to use sprintf    For example   char buffer 50   sprintf  buffer   My String       Good luck

User · Answer

Here is obscure solution  define macro function    define Z x             x  0    A               x  1    B               x  2    C      0      char x       Z 0   Z 1   Z 2

User · Answer

You can t - in C  In C initializing of global and local static variables are designed such that the compiler can put the values statically into the executable  It can t handle non-constant expressions as initializers  And only in C99  you can use non-constant expression in aggregate initializers - not so in C89    In your case  since your array is an array containing characters  each element has to be an arithmetic constant expression  Look what it says about those     An arithmetic constant expression shall have arithmetic type and shall only have   operands that are integer constants   oating constants  enumeration constants  character   constants  and sizeof expressions    Surely this is not satisfied by your initializer  which uses an operand of pointer type  Surely  the other way is to initialize your array using a string literal  as it explains too     All the expressions in an initializer for an object that has static storage duration shall be constant expressions or string literals    All quotes are taken out of the C99 TC3 committee draft  So to conclude  what you want to do - using non-constant expression - can t be done with C  You have several options     Write your stuff multiple times - one time reversed  and the other time not reversed   Change the language - C   can do that all  If you really want to do that stuff  use an array of char const  instead   Here is what i mean by the last option  char const c      ABCD   char const  f        amp c 0    amp c 1    amp c 2    amp c 3     char const  g        amp c 3    amp c 2    amp c 1    amp c 0       That works fine  as an address constant expression is used to initialize the pointers     An address constant is a null pointer  a pointer to an lvalue designating an object of static storage duration  or a pointer to a function designator  it shall be created explicitly using the unary  amp  operator or an integer constant cast to pointer type  or implicitly by the use of an expression of array or function type  The array-subscript    and member-access   and -  operators  the address  amp  and indirection   unary operators  and pointer casts may be used in the creation of an address constant  but the value of an object shall not be accessed by use of these operators    You may have luck tweaking your compiler options - another quote      An implementation may accept other forms of constant expressions

[c] How to Initialize char array from a string

Examples related to c