Thread: make a polynomial from file (linked lists)

im confused as to how to read a file line by line and store them in a linked list say:

2 //2 cases- addition or expansion
1 //case 1- addition
4 //1st polynomial = 4 terms
2 3 //2x^3
4 6
1 0
4 5
3 //2nd polynomial = 3 terms
5 7
3 2
4 5

below is my code so far but i just realized that it is not flexible especially when the first case is an expansion and then the addition case is just second

Code:

void createpoly(pnode **hptr, FILE **fptr){ 
    int coef, pow;
    int i, termcount, temptermcount;
    int count = 0;


    *hptr = (pnode *)malloc(sizeof(pnode)); 
    for(i = 0; fscanf(*fptr, "%d", &i) && !feof(*fptr); i++){
        if(count == 0){ 
            termcount = i; 
            temptermcount = i - 3; 
        }
        count++;


        pnode *temp = *hptr; 
        while(termcount > 0){ \
            // newnode = (pnode *)malloc(sizeof(pnode));
            while(temp->next != NULL){
                temp = temp->next;
            }


            if(temp->next == NULL){
                temp->next = (pnode *)malloc(sizeof (pnode));
                fscanf(*fptr, "%d", &(temp->coef)); 


                fscanf(*fptr, "%d", &(temp->pow));
                temp->next->next = NULL; node


            }


            termcount --;


        }


        if(count == temptermcount){
            termcount = i;
        }


        while(termcount > 0){ //second termcount 


            while(temp->next != NULL){
                temp = temp->next;
            }


            if(temp->next == NULL){
                temp->next = (pnode *)malloc(sizeof (pnode));
                fscanf(*fptr, "%d", &(temp->coef)); //input coef and power
                fscanf(*fptr, "%d", &(temp->pow));
                temp->next->next = NULL; //link last data to end empty node


            }
        termcount --;
        }   


    }


}

Sorry by my ignorance, but, in this context, what is an expansion and how do you differ it from an "addition"?
And, maybe it would be easy to structure your inputs as:

<num-of-polynomials>
<poly1-nth-coef> <poly1-n-1th-coef> ... <poly1-1st-coef>
<poly2-nth-coef> <poly2-n-1th-coef> ... <poly2-1st-coef>
...

Example:

2
2 3
3.14 7.2 1.3

2 polynomials: First: 2x¹+3x⁰; second: 3.14x²+7.2x¹+1.3x⁰

To mount the lists you only need to allocate the nodes and insert them at list head.

if you need to add comments to your file, consider reading the line with fgets() or getline() and strip everything after '//' (or whatever you use as comment mark)... and, of course, ignore empty lines...

Sorry for the late reply, I was confused on how fscanf reads integers from files(the file is required) so i changed my code to be more flexible but now it produces segfault

Code:

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


typedef struct term_tag{
    int coef;
    int exponent;
    struct term_tag *next;
}pnode;


void createpoly();






int main(){
    pnode *poly1 = (pnode *)malloc(sizeof(pnode));
    pnode *poly2 = (pnode *)malloc(sizeof(pnode));
 


    FILE *fp;


    fp = fopen("input.txt","r"); 


    // CASE COUNT 
    if(fp != NULL) createpoly(poly1, poly2, fp);
}




void createpoly(pnode **pptr1, pnode **pptr2, FILE **fptr){
    int case_count, case_num, term_count;
    
    fscanf(*fptr,"%d",&case_count);


    // CASES     
      while(case_count > 0){
          fscanf(*fptr, "%d", &case_num); //read line then move to new line
              if(case_num == 1){ //case 1 
                  fscanf(*fptr, "%d", &term_count); //store line content(ie term count to var)


                  pnode *temp = *pptr1; 
                  while(term_count > 0){
                     while(temp->next != NULL){ //traverse list 
                         temp = temp->next;
                    }
                      if(temp->next == NULL){ //add to tail
                          temp->next = (pnode *)malloc(sizeof (pnode));
                        fscanf(*fptr, "%d", &(temp->coef)); //input coef and power
                        fscanf(*fptr, "%d", &(temp->exponent));
                        temp->next->next = NULL; //link last data to end empty node


                      }
                  term_count--;
                  }


                  
                  fscanf(*fptr, "%d", &term_count); //store line content(ie term count to var)


                  pnode *temp2 = *pptr2; //traverse list
                  while(term_count > 0){
                     while(temp2->next != NULL){
                         temp2 = temp2->next;
                    }
                      if(temp2->next == NULL){ //add to tail
                          temp2->next = (pnode *)malloc(sizeof (pnode));
                        fscanf(*fptr, "%d", &(temp2->coef)); //input coef and power
                        fscanf(*fptr, "%d", &(temp2->exponent));
                        temp->next->next = NULL; //link last data to end empty node


                      }
                  term_count--;
                  }


              }
          case_count--;
      }                                                                                    
   
}