# C > Data Structures Code Examples

## Add two long positive intergers

``` Add two long positive intergers #include<stdio.h> #include<alloc.h> #include<conio.h> #include<ctype.h> struct node { int data; struct node*next; }; void insert(struct node**p,int num) { struct node*temp; if(*p==NULL) { (*p)=(struct node*)malloc(sizeof(struct node)); (*p)->next=NULL; (*p)->data=num; } else { temp=(struct node*)malloc(sizeof(struct node)); temp->next=(*p); (*p)=temp; (*p)->data=num; } } void add_in(struct node*a,struct node*b,struct node**c) { int d,carry; carry=0; struct node*t; while(a!=NULL&&b!=NULL) { d=(a->data+b->data+carry)%10; insert(c,d); if( (a->data+b->data+carry) >= 10) { carry=1; } else carry=0; a=a->next; b=b->next; } if(a==NULL&&b==NULL) { return; } else { if(a!=NULL&&b==NULL) { t=a; } else { t=b; } while(t!=NULL) { d=(carry+t->data)%10; if((carry+t->data)>=10) carry=1; else carry=0; insert(c,d); t=t->next; } if(carry==1) insert(c,carry); } } void numin(struct node**p) { *p=NULL;char c='c'; while(c!='n') { c=getch(); if(!isdigit(c)) return; else { putch(c); insert(p,c-'0'); } } } void disp(struct node*p) { if(p==NULL) return; else { printf("%d",p->data); disp(p->next); } } void main() { struct node *a,*b,*c; clrscr(); a=b=c=NULL; printf("Enter the first number.... "); numin(&a); printf(" Enter the second number.... "); numin(&b); printf(" The added result is... "); add_in(a,b,&c); disp(c); getch(); } ```