#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
 
void foo( const char format[], ... )
{
    va_list args;
    size_t  length = 0;
 
    va_start( args, format );
 
    length = vsnprintf( 0, 0, format, args );
 
    ++length;
    char *pbuffer = new char[length];
 
    vsprintf( pbuffer, format, args ); // тут пробовал и vsnprintf( pbuffer, length, format, args ) с тем же результатом
    printf( "%s", pbuffer );
 
    va_end( args );
 
    delete[] pbuffer;
}
 
int main()
{
    foo( "Hello %s World!\n", "cruel" );
 
    return 0;
}

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