如何使用 fscanf 读取文件以初始化 C 中的值？

Question

Suppose I have Client.txt file that looks like this. Client.txt file picture

1111
Name One
Email.email.1
111-111-1111
2222
Name Two Two
Email.email.2
222-222-2222
3333
Name Three Three
Email.email.3
333-333-3333

The Client txt file contains client's id, name, email, and phone number.

Now the task is to read from the Client file and save id, name, email, and phone number into a struct called Client. From this Client text file, I will make three struct values which are going to be pushed in to a list of structs.

But since I am just learning how to use fscanf, and in an attempt practice fscanf, I am narrowing the task into: how to read from text and initialize the first client's values?

Here is what I attempted.

int main(void){
    FILE *fPtr;
    if((fPtr = fopen("Client.txt"), "r") == NULL){
        puts("File could not be found.");
    }
    else{
        //First Client
        int clientId;//1111
        char clientName[30];//Name One
        char clientEmail[30];//Email.email.1
        char clientPhone[30];//111-111-1111

        //Initialize the first client.
        fscanf(fPtr, "%d%s%s%s", &clientId, clientName, clientEmail, clientPhone);

        //While not end of the file, initialize rest of the clients.
        while(!feof(fPtr)){
            //Have not yet implemented.
        }
        fclose(fPtr);

    }
}

How can I initialize the first client value as

 clientId = 1111
 clientName[30] = Name One
 clientEmail[30] = Email.email.1
 clientPhone[30] = 111-111-1111

Answer 1

Here is a solution, not using scanf but getline

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


typedef struct Client_s
{
        int clientId;
        char clientName[30];
        char clientEmail[30];
        char clientPhone[30];
} Client;

Client* get_next_client(FILE *f_ptr)
{
        Client *new_client = malloc(sizeof(Client));
        char *buff = malloc(30);
        size_t size = 30;
        int error = 0;

        if (new_client == NULL || buff == NULL)
                return NULL;

        if (getline(&buff, &size, f_ptr) <= 0)
                return NULL;
        new_client->clientId = atoi(buff);
        if (getline(&buff, &size, f_ptr) <= 0)
                return NULL;
        strncpy(new_client->clientName, buff, strlen(buff) - 1);
        if (getline(&buff, &size, f_ptr) <= 0)
                return NULL;
        strncpy(new_client->clientEmail, buff, strlen(buff) - 1);
        if (getline(&buff, &size, f_ptr) <= 0)
                return NULL;
        strncpy(new_client->clientPhone, buff, strlen(buff) - 1);

        free(buff);
        return new_client;
}

int main(int ac, char **av)
{
        FILE * f_ptr = fopen("Client.txt", "r");

        if (f_ptr == NULL)
        {
                write(2, "Could not open file\n", strlen("Could not open file\n"));
                return 1;
        }

        Client *client = get_next_client(f_ptr);
        while (client != NULL)
        {
                printf("%d\n", client->clientId);
                //handle client
                client = get_next_client(f_ptr);
        }

        fclose(f_ptr);

        return 0;
}

Don't forget to free the recieved Clients when you don't need them anymore.

Hope if fixes your problem.