Write a program in C language for addition of two numbers which have at least 20 digits each

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{

char str1[21],str2[21];

int i,j,a[20],b[20];

int add[21]={0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

printf("\n Enter number 1:");

for(i=0; i<21; i++)

{

str1[i]=getchar();

}

printf("\n Enter number 2:");

for(i=0; i<21; i++)

{

str2[i]=getchar();

}

//converting char to integer

for(i=0; i<20; i++)

{

a[i]=(int)str1[i]-48;

b[i]=(int)str2[i]-48;

}

printf("\n Print Number 1:");

for(i=0; i<20; i++)

{

printf("%d",a[i]);

}

printf("\n Print Number 2:");

for(i=0; i<20; i++)

{

printf("%d",b[i]);

}

for(i=20; i>-1;i--)

{

j= a[i]+b[i];

if(j<10)

{

add[i] +=j;

}

else

{

add[i]+=(j-10);

add[i-1]+=1;

}

}

printf("\n Print Addition:");

for(i=0; i<20; i++)

{

printf("%d",add[i]);

}

 

getch();

}