c int σε συμβολοσειρα

[gon1332]

Λοιπόν,ο παρακάτω κώδικας απευθύνεται κυρίως στο φίλο gon1332 που ξέρω πως τα γουστάρει κάτι τέτοια, αλλά φυσικά και σε όποιον άλλον διαβάσει το νήμα και το βρει ενδιαφέρον:

 

Κώδικας:

 

 

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

/* Print specified msg (a-la printf) along with debugging information.
 */
#define DBGF( format, ... )                                       \
do {                                                              \
	int c_;                                                   \
	puts("*** RUNTIME ERROR CAUGHT ****");                    \
	fprintf(stderr, "*** File: %s | Line: %d | Func: %s()\n", \
		__FILE__, __LINE__, __func__);                    \
	fprintf(stderr, "%s", "*** ");                            \
	fprintf(stderr, (const char *)(format), __VA_ARGS__);     \
//	fflush(stderr);                                           \
        putchar( '\n' );                    \
} while(0)

/* --------------------------------------------------------------
 * char *vprintf_to_text():
 *
 * This function is a wrapper to ISO C99's vsnprintf(). It creates
 * dynamically the buffer needed to hold the printed output, and if
 * it succeeds it returns a pointer to it. On error, it returns NULL.
 *
 * NOTES:
 *   1. vargs MUST have been already initialized in the caller
 *      (by the va_start macro, and possibly subsequent va_arg
 *      calls).
 *   2. The returned buffer, if non-NULL, MUST be freed in the
 *      calling environment.
 *   3. The function is used in the function: printf_to_text()
 * --------------------------------------------------------------
 */
char *vprintf_to_text( const char *fmt, va_list vargs )
{
	int   nchars = 0;
	char  *buf = NULL;
	size_t bufsz = BUFSIZ;

	/* make buf to hold the text and pass it to vsnprintf */
	if ( NULL == (buf = calloc(1, bufsz)) ) {
		DBGF( "%s", "calloc failed!" );
		goto ret_failure;
	}
	nchars = vsnprintf( buf, bufsz, fmt, vargs );
	if ( nchars < 0 ) {
		DBGF( "%s", "vsnprintf failed!" );
		goto ret_failure;
	}

	/* Was buf too small to hold the text?
	 * Reallocate 1+nchars bytes and re-apply.
	 */
	if ( nchars >= (int)bufsz ) {
		char *try = NULL;
		bufsz = 1 + nchars;   /* for the NUL byte */
		try = realloc( buf, bufsz );
		if ( NULL == try ) {
			DBGF( "%s", "realloc failed!" );
			goto ret_failure;
		}
		buf = try;

		nchars = vsnprintf( buf, bufsz, fmt, vargs );
		if ( nchars < 0 ) {
			DBGF( "%s", "vsnprintf failed!" );
			goto ret_failure;
		}
	}

	return buf;

ret_failure:
	if ( buf ) {
		free( buf );
	}
	return NULL;
}

/* --------------------------------------------------------------
 * char *printf_to_text():
 *
 * This function is similar to ISO C99's snprintf() but it creates
 * dynamically the string needed to hold the print-out. It returns
 * the string, or NULL on error.
 * --------------------------------------------------------------
 */
char *printf_to_text( const char *fmt, ... )
{
	char  *txtout = NULL;

	if ( NULL == fmt ) {
		DBGF( "%s", "NULL pointer argument (fmt)" );
		return NULL;
	}

	va_list vargs;

	va_start( vargs, fmt );
	txtout = vprintf_to_text( fmt, vargs );
	va_end( vargs );

	return txtout;
}

/****************************************************//**
 *
 ********************************************************
 */
char *ullong_to_string( unsigned long long int num, size_t *digcount )
{
	char *ret = printf_to_text( "%llu", num );
	if ( NULL == ret ) {
		DBGF( "%s", "printf_to_text() failed" );
		if ( NULL != digcount ) {
			*digcount = 0;
		}
		return NULL;
	}

	if ( NULL != digcount ) {
		*digcount = strlen( ret );
	}
	return ret;
}

/****************************************************//**
 *
 ********************************************************
 */
int main( void )
{
	size_t n = 0;
	char *s = ullong_to_string( 1254879786879834, &n );

	printf( "%s (%d digits)\n", s, n );
	free( s );

	return 0;
}

 

Όλα τα λεφτά είναι η συνάρτηση: vprintf_to_text() και αμέσως μετά η printf_to_text() που την χρησιμοποιεί.

Ο κώδικας είναι C99, και ουσιαστικά είναι copy & paste από τον κώδικα του 2048cc για όποιον το θυμάται (και πιο συγκεκριμένα από το πηγαίο: common.c).

Χαχαχα. Αυτό ήταν λίγο overkill.