Solving Arithmetic on Large Positive Integers with Bignum Strings

[gruba]

Homework Statement

Write a program (without using GMP library - https://gmplib.org) which performs arithmetic operations on large positive integers (addition, subtraction, multiplication and division). Maximum number of digits in one number is 100.
Large number is the number that can't be represented by standard data types (long long, ...), and it is represented as a string.
Then allow incrementing and decrementing of a string, and finding the smallest and the largest string in an array of n strings.

2. The attempt at a solution

How would you do incrementing, decrementing and comparing Bignum strings?
Here is the addition:

    #include<stdio.h>
    #define MAX 100//max. number of digits
    typedefstruct
    {
        int arr[MAX];//array for one number
    }NUMBER;
    void read(NUMBER *add_num)//read one number
    {
        int i,digit=0;
        char ch[101];
        scanf("%s",ch);

        while(ch[digit])//number of digits
            digit++;

        for(i=0;i < MAX;i++)
        {
            digit--;
            if(digit >=0)
                add_num->arr[i]=ch[digit]-'0';//int to char
            else
                add_num->arr[i]=0;
        }
    }

    void addition(NUMBER a,NUMBER b,NUMBER *add_res)//add two Bignum strings
    {
        int carry=0;
        int i,temp;
        for(i=0;i < MAX;i++)
        {
            temp=a.arr[i]+b.arr[i]+carry;//sum
            add_res->arr[i]=temp %10;//resulting digit
            carry=temp /10;//store carry
        }
    }

    voidprint(NUMBER *add_num)//print result
    {
        int i;

        for(i=MAX-1;add_num->arr[i]==0;i--);//skip the leading zeros

        for(;i>=0;i--)
            printf("%d",add_num->arr[i]);
    }
    int main()
    {
        NUMBER x,y,z;
        printf("enter two positive integers: \n");
        read(&x);
        read(&y);
        printf("addition result: ");
        addition(x,y,&z);
        print(&z);
        return0;
    }

 

[mfb]

Incrementing is just adding 1, and decrementing is subtracting 1 (or adding 9999...99 and ignoring the overflow)

How do you compare numbers like those by eye? The same can be done in code.

35356959849283293
35846625235464635
 4735939384293894

 

[Mark44]

There are a couple of missing spaces in your code, below.
typedefstruct needs a space after typedef
voidprint needs a space after void

Homework Statement

Write a program (without using GMP library - https://gmplib.org) which performs arithmetic operations on large positive integers (addition, subtraction, multiplication and division). Maximum number of digits in one number is 100.
Large number is the number that can't be represented by standard data types (long long, ...), and it is represented as a string.
Then allow incrementing and decrementing of a string, and finding the smallest and the largest string in an array of n strings.

2. The attempt at a solution

How would you do incrementing, decrementing and comparing Bignum strings?
Here is the addition:

    #include<stdio.h>
    #define MAX 100//max. number of digits
    typedefstruct
    {
        int arr[MAX];//array for one number
    }NUMBER;
    void read(NUMBER *add_num)//read one number
    {
        int i,digit=0;
        char ch[101];
        scanf("%s",ch);

        while(ch[digit])//number of digits
            digit++;

        for(i=0;i < MAX;i++)
        {
            digit--;
            if(digit >=0)
                add_num->arr[i]=ch[digit]-'0';//int to char
            else
                add_num->arr[i]=0;
        }
    }

    void addition(NUMBER a,NUMBER b,NUMBER *add_res)//add two Bignum strings
    {
        int carry=0;
        int i,temp;
        for(i=0;i < MAX;i++)
        {
            temp=a.arr[i]+b.arr[i]+carry;//sum
            add_res->arr[i]=temp %10;//resulting digit
            carry=temp /10;//store carry
        }
    }

    voidprint(NUMBER *add_num)//print result
    {
        int i;

        for(i=MAX-1;add_num->arr[i]==0;i--);//skip the leading zeros

        for(;i>=0;i--)
            printf("%d",add_num->arr[i]);
    }
    int main()
    {
        NUMBER x,y,z;
        printf("enter two positive integers: \n");
        read(&x);
        read(&y);
        printf("addition result: ");
        addition(x,y,&z);
        print(&z);
        return0;
    }