How do you declare string constants in C

Question

I know it s quite idiomatic  or good style at least  in C to declare numeric constants as enums instead of  defineing them      bad style     define MAXLINE 1024     good better style    enum       MAX LINE   1024      Is there an equivalent rule for the definition of string constants      is this good style      define HELLO  Hello World      or is this better     const char  HELLO2    Howdy     What do you prefer  If possible show some drawbacks of either method

User · Accepted Answer

There s one more  at least  road to Rome   static const char HELLO3      Howdy      static     optional     is to prevent it from conflicting with other files   I d prefer this one over const char   because then you ll be able to use sizeof HELLO3  and therefore you don t have to postpone till runtime what you can do at compile time   The define has an advantage of compile-time concatenation  though  think HELLO    World    and you can sizeof HELLO  as well   But then you can also prefer const char  and use it across multiple files  which would save you a morsel of memory   In short     it depends

User · Answer

One advantage  albeit very slight  of defining string constants is that you can concatenate them at compile time    define HELLO  hello   define WORLD  world   puts  HELLO WORLD      Not sure that s really an advantage  but it is a technique that cannot be used with const char   s

User · Answer

If you want a  const string  like your question says  I would really go for the version you stated in your question      first version    const char  HELLO2    Howdy     Particularly  I would avoid      second version    const char HELLO2      Howdy     Reason  The problem with second version is that compiler will make a copy of the entire string  Howdy   PLUS that string is modifiable  so not really const    On the other hand  first version is a const string accessible by const pointer HELLO2  and there is no way anybody can modify it

User · Answer

Their are a few differences    define HELLO  Hello World    The statement above can be used with preprocessor and can only be change in the preprocessor   const char  HELLO2    Howdy     The statement above can be changed with c code  Now you can t change the each individual character around like the statement below because its constant   HELLO2 0     a    But you what you can do is have it point to a different string like the statement below  HELLO2    HELLO WOLRD    It really depends on how you want to be able to change the variable around  With the preprocessor or c code

User · Answer

The main disadvantage of the  define method is that the string is duplicated each time it is used  so you can end up with lots of copies of it in the executable  making it bigger

[c] How do you declare string constants in C?

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