Question
Transcribed Text
Assignment
Write a function that takes a buffer, a format string and three pointers to values and composes a string with
the same text that would be printed if format was used on printf. The function should return
the
number
of
bytes written in to the buffer, if the number of placeholders is bigger than 3 return - -1, if its less
use
only
the
arguments needed.
Assumptions
1. The buffer is big enough to contain the formatted string.
prototype
int format_to_string(char *buffer, const char *format, void *arg1, void *arg2,
void *arg3);
Supports
Your function must support the following placeholders,
1. %c - interpret the argument as char
and add the char to the buffer.
2. %d - interpret the argument as int
and add the string representation of the int to the buffer.
3. %s - interpret the argument as char * and add the string to the buffer.
4.
%x - interpret the argument as int * and add the string representation of the int as hexadecimal
characters to the buffer.
1
5.
%f - interpret the argument as float and add the string representation of the float with a precision
of at most 7 digits with no trailing zeros, i.e. 1/4 should be added as 0.25 and 1/3 as 0. . 3333333.
6. %% - prints the symbol '%'.
Theoretical question
Write the answers to the following question as documentation to your function
1. Mention two format strings that your code is not handling correctly.
2. What is the behavior of the function for these format strings.
Make sure your code does not crash for the format strings you mentioned.
Solution Preview
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#include <string.h>#include <stdlib.h>
#include <stdio.h>
#define MAX_SIZE (256)
#define ASSERT_EQUAL(x,y,msg) do {\
if ((x) != (y)) {\
printf("%s - Failed\n", msg);\
printf("Expected %d bytes and received %d\n", (x), (y));\
} else {\
printf("%s - Passed\n", msg);\
}\
} while(0)
#define ASSERT_STRING_EQUAL(x,y,msg) do {\
if (strncmp((x), (y), MAX_SIZE) != 0) { \
printf("%s - Failed\n", msg); \
printf("Expected:\n%s\nOutput:\n%s\n", (x), (y));\
} else {\
printf("%s - Passed\n", msg);\
}\
} while(0)
int format_to_string(char *buffer,const char *format,void *arg1,void *arg2,void *arg3);
int main(void)
{
char buffer[MAX_SIZE] = {0};
char test_buffer[MAX_SIZE] = {0};
int num_bytes = 0;
int test_num_bytes = 0;
int arg11 = 1;
char arg12 = 'd';
char *arg13 = "Hello";
num_bytes = sprintf(buffer, "arg1 = %d, arg2 = %c, arg3 = %s\n", arg11, arg12, arg13);
test_num_bytes = format_to_string(test_buffer, "arg1 = %d, arg2 = %c, arg3 = %s\n", &arg11, &arg12, arg13);
ASSERT_EQUAL(num_bytes, test_num_bytes, "Test1");
ASSERT_STRING_EQUAL(buffer, test_buffer, "Test2");
int arg21 = 33;
char *arg22 = "Hello";
int arg23 = 43;
memset(buffer, 0, MAX_SIZE);
memset(test_buffer, 0, MAX_SIZE);
num_bytes = sprintf(buffer, "%% arg1 = %d, arg2 = %s, %% arg3 = %x\n", arg21, arg22, arg23);
test_num_bytes = format_to_string(test_buffer, "%% arg1 = %d, arg2 = %s, %% arg3 = %x\n", &arg21, arg22, &arg23);
ASSERT_EQUAL(num_bytes, test_num_bytes, "Test3");
ASSERT_STRING_EQUAL(buffer, test_buffer, "Test4");
float arg31 = 1.0/3;
float arg32 = 5.0/4;
memset(buffer, 0, MAX_SIZE);
memset(test_buffer, 0, MAX_SIZE);
strcpy(buffer, "% arg1 = 0.3333333, arg2 = 1.25\n");
num_bytes = strlen(buffer);
test_num_bytes = format_to_string(test_buffer, "%% arg1 = %f, arg2 = %f\n", &arg31, &arg32, NULL);
ASSERT_EQUAL(num_bytes, test_num_bytes, "Test5");
ASSERT_STRING_EQUAL(buffer, test_buffer, "Test6");
int arg41 = 33;
char *arg42 = "Hello";
int arg43 = 43;
test_num_bytes = format_to_string(test_buffer, "arg1 = %d, arg2 = %s, arg3 = %d %c\n", &arg41, arg42, &arg43);
ASSERT_EQUAL(test_num_bytes...
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