Thread: program prints extra zero at the end

my program prints an extra zero in the end, and I tried removing the malloc in main and allocate inside the function but it just produces a segfault

Code:

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


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


typedef struct expression{ //expansion
    int num_terms;
    int exponent;
    pnode *terms;
}expr;


void printlist();
// void printexpr();
void createpoly();
void nodesort();
int addpoly();
void display();


int main(){
    pnode *poly1 = (pnode *)malloc(sizeof(pnode)); 
    pnode *poly2 = (pnode *)malloc(sizeof(pnode));
    // expr *expr1 = (expr *)malloc(sizeof(expr));
    // expr *expr2 = (expr *)malloc(sizeof(expr));
 


    FILE *fp;


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


    // CASE COUNT 
    if(fp != NULL){
        createpoly(&poly1, &poly2, &fp);
        printf("  ");
        printlist(poly1);
        printf("\n+ ");
        printlist(poly2);
        printf("\n");


    }


    return 0;
}




void printlist(pnode * pptr) { //pass the test list as parameters
    pnode * temp = pptr; //temp same as where head is pointing


    while (temp->next != NULL) { 
            if(temp->exponent == 1) //won't print exponent one anymore
                printf("%dx + ",temp->coef);
            if(temp->exponent == 0) //won't print x if expo is 0
                printf("%d + ",temp->coef);
            else
                printf("%dx^%d + ",temp->coef,temp->exponent);
            temp = temp->next;


    } //repeat till NULL meaning end of list




    if(temp->next == NULL){
        if(temp->exponent == 0){
                printf("%d", temp->coef);
                return;
        }
        if(temp->exponent == 1){
            printf("%dx", temp->coef);
            return;
        }
        else{
            printf("%dx^%d", temp->coef, temp->exponent);
            return;
        }
    }
    printf("\n");
}


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
              // ADDITION
              if(case_num == 1){ 
                  fscanf(*fptr, "%d", &term_count); //store line content(ie term count to var)




                  pnode *temp = *pptr1; 
                  while(term_count > 0){
                      if(temp == NULL){
                          temp = (pnode*)malloc(sizeof(pnode));
                          temp->next = NULL;




                      }
                     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 exponenter
                        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){ 
                          temp2->next = (pnode *)malloc(sizeof (pnode));
                        fscanf(*fptr, "%d", &(temp2->coef)); 
                        fscanf(*fptr, "%d", &(temp2->exponent));
                        temp->next->next = NULL; 
                      }
                  term_count--;
                  }


              }


          case_count--;
      }                                                                                    
   
}

The output goes like this:

Code:

   5x^12 + 2x^9 + 4x^7 + 6x^6 + 1x^3 + 0
+ 7x^8 + 2x^7 + 8x^6 + 6x^4 + 2x^2 + 3x + 3x^1 + 40 + 0