sol1.c File Reference

Problem 13 solution More...

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

Include dependency graph for sol1.c:

Macros
#define	N   10
	number of digits of the large number
#define	N2   (N + 10)
	number of digits in output number

Functions
int	get_number (FILE *fp, char *buffer, uint8_t *out_int)
	Function to read the number from a file and store it in array. More...
int	add_numbers (uint8_t *a, uint8_t *b, uint8_t N)
	Function to add arbitraty length decimal integers stored in an array. More...
int	print_number (uint8_t *number, uint8_t N, int8_t num_digits_to_print)
	Function to print a long number.
int	main (void)
	Main function.

Detailed Description

Problem 13 solution

Author

Krishna Vedala

Function Documentation

add_numbers()

int add_numbers	(	uint8_t *	a,
		uint8_t *	b,
		uint8_t	N
	)

Function to add arbitraty length decimal integers stored in an array.

a + b = c = new b

{
    int carry = 0;
    uint8_t *c = b; /* accumulate the result in the array 'b' */
 
    for (int i = 0; i < N; i++)
    {
        // printf("\t%d + %d + %d ", a[i], b[i], carry);
        c[i] = carry + a[i] + b[i];
        if (c[i] > 9) /* check for carry */
        {
            carry = 1;
            c[i] -= 10;
        }
        else
            carry = 0;
        // printf("= %d, %d\n", carry, c[i]);
    }
 
    for (int i = N; i < N + 10; i++)
    {
        if (carry == 0)
            break;
        // printf("\t0 + %d + %d ", b[i], carry);
        c[i] = carry + c[i];
        if (c[i] > 9)
        {
            carry = 1;
            c[i] -= 10;
        }
        else
            carry = 0;
        // printf("= %d, %d\n", carry, c[i]);
    }
    return 0;
}

get_number()

int get_number	(	FILE *	fp,
		char *	buffer,
		uint8_t *	out_int
	)

Function to read the number from a file and store it in array.

index 0 of output buffer => units place
index 1 of output buffer => tens place and so on i.e., index i => 10^i th place

{
    long l = fscanf(fp, "%s\n", buffer);
    if (!l)
    {
        perror("Error reading line.");
        return -1;
    }
    // printf("Number: %s\t length: %ld, %ld\n", buffer, strlen(buffer), l);
 
    long L = strlen(buffer);
 
    for (int i = 0; i < L; i++)
        if (buffer[i] < 0x30 || buffer[i] > 0x39)
        {
            perror("found inavlid character in the number!");
            return -1;
        }
        else
            out_int[L - i - 1] = buffer[i] - 0x30;
 
    return 0;
}