Macro uses as string cause initializer-string for array of chars is too long

Question

I'm currently trying to make a C library that would allow me to make any kind of log i want in my future projets.

In order to do it i've set few thing such as colors, bold ...

#define RESET               "\033[0m"
#define BOLD(msg)           "\033[1m" msg RESET
#define BLINK(msg)          "\033[5m" msg RESET

#define YELLOW(msg)         "\033[38;5;208m" msg RESET
#define ORANGE(msg)         "\033[38;5;208m" msg RESET
#define RED(msg)            "\033[38;5;196m" msg RESET
#define BLUE(msg)           "\033[38;5;27m" msg RESET
#define GREEN(msg)          "\033[38;5;46m" msg RESET
#define PURPLE(msg)         "\033[38;5;164m" msg RESET

#define NULL_STR            ""
#define INFO_STR            "[" BOLD(YELLOW("INFO")) "] "
#define WARN_STR            "[" BOLD(ORANGE("WARNING")) "] "
#define ERROR_STR           "[" BLINK(BOLD(RED("ERROR"))) "] "
#define DEBUG_STR           "[" BOLD(BLUE("DEBUG")) "] "
#define UNKNOWN_TYPE_STR    "[" BOLD(PURPLE("UNKNOWN TYPE")) "] "

In order to build the string berfore printing it, i've set an array of my string that is use with an enum :

typedef enum log_type_e {
    NONE = 0,
    INFO = 1,
    WARN = 2,
    ERRO = 4,
    DEBUG = 8
} log_type_t;


// I put both of my tries they lead to the same issue
static const char (*LOG_TYPE_STR)[] = {NULL_STR, INFO_STR, WARN_STR, UNKNOWN_TYPE_STR, ERROR_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, DEBUG_STR};

//the 9 has to be set or it lead to an error
static const char LOG_TYPE_STR[][9] = {NULL_STR, INFO_STR, WARN_STR, UNKNOWN_TYPE_STR, ERROR_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, DEBUG_STR};

When i compile a program that use the LOG_TYPE_STR array, i got this warning a lot of times :

initializer-string for array of chars is too long
   16 | #define INFO_STR    "[" BOLD(YELLOW("INFO")) "] "

If anyone could help me to understand an fix it or if anyone know how i could build my strings dynamical this would be really appreciate. Thanks

The definition static const char LOG_TYPE_STR[][9] allows only 8 characters in a nul-terminated string, but your macros are building strings that are longer. INFO_STR in the error message is used as an initialiser, but even the YELLOW part is too long on its own. — Weather Vane
– Weather Vane, Commented Jun 23, 2020 at 21:09
YELLOW adds 15 characters to a string. BOLD adds 8 characters. So BOLD(YELLOW("INFO")) is 27 characters long (plus 1 for the null terminator). — Barmar
– Barmar, Commented Jun 23, 2020 at 21:11

Barmar · Accepted Answer · 2020-06-23 21:15:57Z

2

Your string size 9 doesn't allow room for all the escape sequences and other wrapper characters. INFO_STR needs 30 bytes, UNKNOWN_TYPE_STR needs 39 bytes.

You should be able to do it with the array of pointers to string literals. You just got the syntax a little wrong. Get rid of the parentheses.

static const char *LOG_TYPE_STR[] = {NULL_STR, INFO_STR, WARN_STR, UNKNOWN_TYPE_STR, ERROR_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, UNKNOWN_TYPE_STR, DEBUG_STR};

answered Jun 23, 2020 at 21:15

Barmar

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