usaa19cv7/a_train.c

#include "a_train.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct car* add_car(struct car* first,const char* target) {
    struct car* newcar = (struct car*)malloc(sizeof(struct car));
    strcpy(newcar->value, target);
    newcar->next = NULL; 
    if(first == NULL){
        first = newcar;
        return first;
    }else{
        struct car* this = first;
        while(this->next != NULL){
            this = this->next;
        }
        this->next = newcar;
               
       
        
        
    }
   
    return first;
}

void print_train(struct car* first) {
    struct car* this = first;   
    while(this != NULL){
        printf("%s \n",this->value);
        this = this->next;
    }
    printf("\n");
}

void cancel_train(struct car* first) {
   /* if (first!=NULL){
        cancel_train(first->next);
        free(first);
        first = NULL;
    }*/
     
    struct car* next; 
    while (first != NULL)  { 
        next = first->next; 
        free(first); 
        first = next; 
    } 
    first = NULL;
}


struct car* clear_train(struct car* first, const char* target) {
    if(first == NULL){
        return NULL;
    }
    if(first->next == NULL){
        if(strcmp(first->value,target)== 0){
            return NULL;
        }else{
            return first;
        }
    }
    struct car* prev = first;
   /* if(strcmp(prev->value,target)== 0){
        struct car* one = prev->next;
        free(prev);
        prev= one;
        //free(one);
        //one = NULL;
        return first;
    }*/
    while (prev->next->next != NULL){
        if(strcmp(prev->next->value,target)== 0){
            struct car* third = prev->next->next;
            free(prev->next);
            prev->next = third;
            return first;
        }
        prev = prev->next;
    }
    if(strcmp(prev->next->value,target)== 0){
            
        free(prev->next);
        prev->next = NULL;
        return first;
    }
  

    
    
	return first;
}