Scott wrote:
>Here are the relevant portions of indatax.c:
>char *namectrl = NULL;
>char *name1 = NULL;
>char *name2 = NULL;
>typedef struct {
> char *var; /* destination for storage of the data */
> size_t len; /* max len of the data */
> char *(*xlat)(); /* translation routine */
>} DATUM;
>DATUM recip_data[] = {
>{ namectrl, NAMECTRL_LEN, make_upper },
>{ name1, NAME1_LEN, make_upper },
>{ name2, NAME2_LEN, make_upper },
>[...]
>And these are the errors...
>indatax.c:124: initializer element is not constant
>indatax.c:124: (near initialization for `recip_data[0].var')
>indatax.c:125: initializer element is not constant
>indatax.c:125: (near initialization for `recip_data[1].var')
>indatax.c:126: initializer element is not constant
>indatax.c:126: (near initialization for `recip_data[2].var')
>[...]
First, I would upgrade to a more modern version of gcc. The
current release is the 3.4 series.
Secondly, I tried the following program,
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include <stdio.h>
#include <stdlib.h>
#define NAMECTL_LEN 15
#define NAME_LEN 10
typedef struct tag_datum
{
char* var;
size_t len;
char *(*xlat)();
} datum;
char* make_upper()
{
return NULL;
}
int main(int argc, char** argv)
{
char* namectrl = NULL;
char* name1 = NULL;
char* name2 = NULL;
datum data[] = {{namectrl, NAMECTL_LEN, make_upper},
{name1, NAME_LEN, make_upper},
{name2, NAME_LEN, make_upper}};
return 0;
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
When I compiled this program using gcc 3.4.2 with the flags `-ansi
-pedantic -Wall' I get a number of warnings stating:
"Initializer element is not computable at load time"
Two per each line of initializing data. My guess is that the compiler
can-not figure out how to initialize the first element of the structure
at run time because namectrl has yet to "created".
However, all is not lost, changing the program to:
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
#include <stdio.h>
#include <stdlib.h>
#define NAMECTL_LEN 15
#define NAME_LEN 10
typedef struct tag_datum
{
char* var;
size_t len;
char *(*xlat)();
} datum;
char* make_upper()
{
return NULL;
}
int main(int argc, char** argv)
{
datum data[] = {{NULL, NAMECTL_LEN, make_upper},
{NULL, NAME_LEN, make_upper},
{NULL, NAME_LEN, make_upper}};
return 0;
}
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
results in a clean compilation (except for a warning about
an unused variable). To initialize the var member of datum, you
should be able to do something like:
if(NULL != (data[0].var = malloc(NAMECTL_LEN*sizeof(char))))
{
strncpy(data[0].var, "test string", NAMECTL_LEN);
}
and you should be able to use datum like this:
int i, num = sizeof(data)/sizeof(datum);
for(i = 0; i < num; i++)
{
printf("data point %d, var %s\n", i, (data[i].var ? data[i].var : "N/A"));
}
hope this helps,
George
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