usaa20/cv5/a_train.c

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

#include "a_train.h"

struct car* add_car(struct car* first,const char* target) {
    struct car* newcar = calloc(1, sizeof(struct car));
    strcpy(newcar->value, target);
    if(first == NULL){
        return newcar;
    }
    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;
    if(first == NULL){
        exit(0);   
    }
    else{
        while(this != NULL){
            printf("%s\n", this->value);
            this = this->next;
        }
    }
}

void cancel_train(struct car* first) {   
    struct car* this;
    if(first == NULL){
        exit(0);
    }
    else if(first->next == NULL){
       this = first;
       first = first->next;
       free(this);
       first = NULL;
    }
    else{
        struct car* prev = first;
        while(prev->next->next != NULL){
            prev = prev->next;
        }
        this = prev->next;
        prev->next = NULL;
        free(this);
    }
    //cancel_train(first->next);
    //free(first);

}



struct car* clear_train(struct car* first, const char* target) {
    struct car* this = first;
    while(this != NULL){
        if(this->value == target){
            return NULL;    
        }
        this = this->next;
        
    }
    return first;
}