Need some Help with this function: Info and Restrictions: // print2505() is our

Question

Need some Help with this function:

Info and Restrictions:

// print2505() is our variant of the of the printf() function.
//
// Like printf(), our function has a formatting string and conversion
//specifiers. Unlike printf(), the data or variables we're printing
// reside in the array pointed to by the data parameter.Further, for
// simplicity our function will only print unsigned numbers.
//
// Pre:
//      out-Points to an already opened file stream.
//      format-Points to a C string containing formatting information
// and is not NULL.
//      data-Points to array of uint8_t values or may be NULL when there
//               are no conversion specifiers in the formatting string.
//
// Post:
//      The conversion specifiers and characters in the formatting string are
//      printed using the provided char_out() function. If an invalid
//      conversion specifier is encountered then no more conversion specifiers
//      or characters are processed or printed.
//
// Returns:
//      The number of characters printed. If an invalid conversion specifier is
//      encountered then return -1.
//
// Restrictions:
//      -You may NOT use array brackets for this assignment. Any array
//      accesses must use pointer arithmetic and the dereference operator.
//      -You may NOT use I/O, e.g. printf(), scanf(), fgets(), or variants.
//      -You may NOT use arrays, beyond the given parameters format and data.
//      -You may NOT use other libraries or built-in functions to convert to
//       or from big or little endian format.
//      -You may NOT use math.h or string.h, nor any function declared within.
//      -Further, you MUST use the provided char_out() function to print the
//       characters one at a time.
//
// See the header comments for more examples and information.
// int print2505(FILE *out, const char *format, const uint8_t *data);

print2505.c: (function that needs to change)

#include <stdio.h>
#include <stdint.h>

#include "char_out.h"
#include "print2505.h"

//
//
//
//
int print2505(FILE *out, const char *format, const uint8_t *data)
{
   int char_count = 0;

   while (*format != '')
   {
       char_out(out, *format);
       char_count++;

       format++;
   }

   return char_count;
}

print2505.h: (do not modify)

#ifndef PRINT2505_H
#define PRINT2505_H

#include <stdio.h>
#include <stdint.h>

// Restrictions:
//   -You may not use array brackets for this assignment. Any array
//   accesses must use pointer arithmetic and the dereference operator.
//    -You may NOT use I/O, e.g. any printf() or scanf() variants.
//    -You may NOT use arrays, beyond the given parameters format and data.
//   -You may NOT use other libraries or built-in functions to convert to
//   or from big or little endian format.
//    -You may NOT use math.h or string.h, nor any function declared within.
//    -Further, you MUST use the provided char_out() function to print the
//    characters one at a time.
//
// Examples:
//    Unless you encounter a conversion specifier, each character
//    should be printed as shown in the formatting string. Like printf(),
//    our conversion specifiers start with a %. The following examples
//    without % characters would just print the given string literals:
//
//      // prints "Hello World!", returns 12
//    print2505("Hello World!", NULL);
//
//   // prints "Hello   wOrLd", returns 11
//    print2505("Hello wOrLd", NULL);
//
//    When a % is encountered, we will normally examine the data parameter.
//    print2505() conversion specifiers start with %, followed by a number
//    (1, 2, 4, or 8 only), which is the number of bytes for the value we
//    are reading from *data, then a lower case 'b' or 'l' for big endian or
//    little endian.
//
//    The following are the valid conversion specifiers:
//       %1b, %1l, %2b, %2l, %4b, %4l, %8b, %8l
//
//      print2505() also supports "%%", a special case, which prints
//    the literal %, and doesn't look at the data parameter.
//
//   The example below will read 2, 2 byte values from the array pointed
//   to by data, interpreting the first value in little endian byte ordering
//   as 34816 (0x8800), and interpreting the the second in big endian byte
//      ordering as 132 (0x0084).
//
//   uint8_t data[] = {0x00, 0x88, 0x00, 0x84};
//
//      // prints "Hello   World % 34816 132", returns 24
//   print2505("Hello World %% %2l %2b ", data);
//
//    If an invalid conversion specifier is encountered, i.e. "%l2", "% b",
//   "%9l" you should stop processing the formatting string (and printing),
//   and then return -1:
//
//      // prints "Hello   World % ", returns -1
//   print2505(stdout, "Hello World %% %l2 %2b ", data);
//
int print2505(FILE *out, const char *format, const uint8_t *data);

#endif

char_out.c: (do not modify)

#include "char_out.h"

//
//
//
//
void char_out(FILE *out, char c)
{
   fprintf(out, "%c", c);
}

char_out.h: (do not format)

#ifndef CHAR_OUT_H
#define CHAR_OUT_H

#include <stdio.h>

void char_out(FILE *out, char c);

#endif

main.c: (do not modify)

#include <stdio.h>
#include <stdbool.h>
#include <stdint.h>
#include <inttypes.h>

#include "char_out.h"
#include "print2505.h"

int main()
{
   // Some tests without conversion specifiers.
    printf(" %d ", print2505(stdout, "Hello World!", NULL));
    printf(" %d ", print2505(stdout, "Hello wOrLd", NULL));

   // Example from the pdf document.
   uint8_t data[] = {0x01, 0x00, 0x00, 0x88, 0x00, 0x0a, 0x01, 0x00,
               0x0b, 0x02, 0x20, 0x03, 0x01, 0x01, 0x02, 0x0b,
                0x02, 0x01, 0x04, 0x01, 0x01, 0x02, 0x0c, 0x01,
               0x00, 0x07, 0x01, 0x01, 0x05, 0x01};

   print2505(stdout, "%% %1b, %1l, %2b, %2l, %4b, %4l, %8b, %8l ", data);

   // Examples from the comments in print2505.h.
   uint8_t more[] = {0x00, 0x88, 0x00, 0x84};

   printf(" %d ", print2505(stdout, "Hello World %% %2l %2b", more));
   printf(" %d ", print2505(stdout, "Hello World %% %l2 %2b ", more));

   return 0;
}

Explanation / Answer

int print2505(FILE *out, const char *format, const uint8_t *data) { int char_count = 0; while (*format) { char_out(out, *format); char_count++; format++; } return char_count; }

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.