problems with sprintf()

[huskers]

I am trying to print the sql values in a buffer and then try to print it. But the prbuf in the below chunk does not print anything. prbuf is defined as below:

char returnbuf[2023] = "No Info found!\n" ;
char *prbuf = &returnbuf[0] ;

case SQL_TYP_NINTEGER: /* long with null indicator */
prbuf += sprintf(prbuf, "%ld", *(long *) ptr) ;
/** this does not work **/
printf("buffer: %s\n", prbuf ) ;
lptr = (long *) ptr ;
/** this prints a value **/
printf("value: %*ld\n", maxCollen, *lptr ) ;
break ;

Am I missing anything or is there any problem with sprintf funtion.

Thanks

 

[rosenk]

prbuf is pointing to the start of the buffer and you're using [tt]sprintf[/tt] to insert the long into it (null terminated.) In the same statement (with [tt]prbuf +=[/tt]) you're incrementing prbuf by the length of the string inserted, so it now points at the null. That's what you're printing with the printf.

The following would work:
[tt]char returnbuf[2023] = "No Info found!\n" ;
char *prbuf = &returnbuf[0] ;

case SQL_TYP_NINTEGER: /* long with null indicator */
sprintf(prbuf, "%ld", *(long *) ptr) ;
printf("buffer: %s\n", prbuf ) ;
[/tt]

So would:
[tt]char returnbuf[2023] = "No Info found!\n" ;
char *prbuf = &returnbuf[0] ;

case SQL_TYP_NINTEGER: /* long with null indicator */
prbuf += sprintf(prbuf, "%ld", *(long *) ptr) ;
printf("buffer: %s\n", returnbuf) ;
[/tt]