Size of the string

[GaPe]

Hi!

I have a function "void Message (char *Message, ...);". Now I want to know the size of the string Message in that the same function. How do I do that?

[Brian]

If it is null terminated strlen() in string.h will tell you the length. Otherwise you'll have to pass the length to the function manually.

[GaPe]

Eh, maybe I wasn't clear enough. Look I know the strlen function, but how do you determine the length of the string if it is declared as "hello, my name is %s". How do you know the length of %s???

[Thantos]

%s is two characters.

Post some code because you aren't being very clear.

[aerian]

If I understand what do you want, you can print that string to a string using sprintf, which will print also substitution for %s and then use strlen() on the result.

[Dave_Sinkula]

Is this close to what you are trying to find, GaPe?

#include <stdio.h>
#include <string.h>
#include <stdarg.h>

void Message(const char *fmt, ...)
{
   va_list  args;
   char     *arg;
   int      length;

   va_start(args, fmt);
   length = vprintf(fmt, args);
   arg = va_arg(args, char*);
   va_end(args);

   printf("\nlength (with substitution) = %d\n", length);
   printf("strlen(\"%s\") = %lu\n", fmt, (long unsigned)strlen(fmt));
   printf("strlen(\"%s\") = %lu\n", arg, (long unsigned)strlen(arg));
}

int main(void)
{
   Message("hello, my name is %s", "Dave Sinkula");
   return 0;
}

/* my output
hello, my name is Dave Sinkula
length (with substitution) = 30
strlen("hello, my name is %s") = 20
strlen("Dave Sinkula") = 12
*/

[edits][more edits][yet another edit, subsequent posts deleted]

[Quantrizi]

Originally posted by Dave_Sinkula
Is this close?

#include <stdio.h>
#include <string.h>
#include <stdarg.h>

void Message(const char *fmt, ...)
{
   va_list  args;
   char     *arg;

   va_start(args, fmt);
   arg = va_arg(args, char*);
   va_end(args);

   printf("strlen(\"%s\") = %lu\n", fmt, (long unsigned)strlen(fmt));
   printf("strlen(\"%s\") = %lu\n", arg, (long unsigned)strlen(arg));
}

int main(void)
{
   Message("hello, my name is %s", "Dave Sinkula");
   return 0;
}

/* my output
strlen("hello, my name is %s") = 20
strlen("Dave Sinkula") = 12
*/

[edits]

The reason for getting: strlen("hello, my name is %s") = 20
strlen("Dave Sinkula") = 12

Is because your printf function

printf("strlen(\"%s\") = %lu\n", fmt, (long unsigned)strlen(fmt));

has strlen(\"%s\") inside of quotes. If you want to display it correctly, replace your printf code to this:

printf(strlen(\"%s\") = %lu\n", fmt, (long unsigned)strlen(fmt));

Because in printf, if u do this: printf("strlen(hi)"); it'll output strlen(hi), but if yo uuse printf(strlen(hi)); you'll get the string length.

[Quantrizi]

Originally posted by Dave_Sinkula
??? Did you try this? It is not even valid syntax.

The output shown is what I intended.

If the output shown is what you intended, then WTF is the problem?

[Quantrizi]

Originally posted by Dave_Sinkula
>If the output shown is what you intended, then WTF is the problem?

I am not the OP asking the question. Read the whole thread (or maybe, RTFT).

Maybe I did RTFT. You are not making any sense of what you want.

If you wish to continue an argument w/ this, PM me

[GaPe]

Thank you Dave_Sinkula.

[Hammer]

>>but if yo uuse printf(strlen(hi)); you'll get the string length.
No you won't That snippet of code is invalid.