C Split String and Use It For Struct

问题

I need to create a phonebook in C, with structs and linked-list.

Data will be on a file. I'll store data like

Name1#Surname1#Date1#Number1
Name2#Surname2#Date1#Number2
Name3#Surname3#Date1#Number3

But I couldn't split by delimiter "#" and use datas in my struct. Here is my code:

#include <stdio.h>
#include <locale.h>

//Veri Yapısı:
typedef struct kisi
{
    char isim[50];
    char soyisim[50];
    int dYili;
    char telefon[16];
    struct kisi *sonraki; 
}Kisi;
int main()
{
    //Türkçe çıktılarda sorun yaşamamak için:
    setlocale(LC_ALL,"Turkish");
    //Dosya yolunu sabitle:
    char *dosyaYolu = "rehber.dat";
    //Dosyayı aç:
    FILE *dosya;
    //Okuma modunda
    dosya = fopen(dosyaYolu,"r");
    //Eğer dosya açılmazsa:
    if(dosya == NULL) 
    {
        printf("Dosya açılamadı. Yolu doğru girdiğinizden emin olun.\n===============================\n\n");
        main(); 
    }
    //Dosya açıldı.
    else
    {
        Kisi *liste = (Kisi*)malloc(sizeof(Kisi));
        Kisi *iter = liste;
        //Dosyanın sonuna kadar oku:
        while(!feof(dosya))
        {
             char *veri;
             fscanf(dosya,"%s",veri);
             char *tok = strtok(veri, "#");
             int sayac = 0;
            while(tok != NULL)
            {
             switch(sayac)
             {
              case 0: strcpy(iter->isim,tok);
                   break;
              case 1: strcpy(iter->soyisim,tok);
                   break;
              case 2: iter->dYili = (int)tok;
                   break;
              case 3: strcpy(iter->telefon,tok);
                   break;
             }
             sayac++;
             tok = strtok(NULL, "#");
            }
            iter->sonraki = (Kisi*)malloc(sizeof(Kisi));
            iter = iter->sonraki;
        }//while sonu
       //Dosyayla işimiz bitti. Kapat:
       fclose(dosya);
    }
    system("pause>null");
}

What I need to do is:

Read data from a file
Use data for struct
Link structs
Add a new person, delete a person etc. (I didn't try to do them yet, there's nothing about this in my code)

My problem is, when I run this program, it stops working. When I remove that while loop with switch-case and just printf my token, it works.

Additional information:

I've to use a file to store my data
I've to use structs and linked lists
Every person must be in its own struct (1 struct = 1 person, the same struct of course)
This program cannot contain C++ codes.

回答1:

You have 2 important problems causing undefined behavior and hence the problem in your program

You don't allocate space for veri in the outer while loop
```
char *veri;
fscanf(dosya,"%s",veri);
```
you should at least do something like
```
char veri[100];
fscanf(dosya,"%99s",veri);
```
You assign the value of a pointer to an int
```
iter->dYili = (int)tok
```
you should, convert the string to an int by means of strtol this way
```
iter->dYili = strtol(tok, NULL, 10);
```
if you want to check for conversion error delcare a char *endptr; at the beginig of the loop and do this
```
iter->dYili = strtol(tok, &endptr 10);
if (*endptr != '\0')
    anErrorOccurredHandleIt();
```

Also, don't forget to free all the malloced pointers, and I think fgets would do a better job in this situation.

来源：https://stackoverflow.com/questions/27807662/c-split-string-and-use-it-for-struct

标签

struct

linked-list