How to store data from files to an array in C - c

Question

So, basically this code below need the user to login first, then after the user login it will show the user details like the one stored in the user.txt. after that i dunno how to retrieve back the files from the files then return it as an array, so that i can update e.g change the name of the user, or delete the user details by taking the array index
here is my code
#include <stdio.h>
#include <string.h>
typedef struct {
char fullname[30];
char dob [10];
int contactNo;
int postcode;
}userDetails;
int main ()
{
char username [15];
char pwd [20];
char user_pass [30];
char userfile [100];
FILE *user;
FILE *admin;
userDetails myUser;
admin = fopen ("admin.txt","r");
printf("Please enter your Username\n");
scanf("%s",username);
printf("Please enter your Password\n");
scanf("%s",pwd);
user_pass[strlen(username) + strlen(pwd) + 2];
sprintf(user_pass, "%s;%s", username, pwd);
while (fgets(userfile, 100, admin) != NULL) {
if (strcmp(userfile, user_pass) == 0) {
printf("Authentication as %s successful\n", username);
size_t nread; // Printing the user information
user = fopen("user.txt", "r");
printf("\nHere is the registered user:\n");
if (user) {
while ((nread = fread(myUser.fullname, 1, sizeof myUser.fullname, user)) > 0)
fwrite(myUser.fullname, 1, nread, stdout);
if (ferror(user)) {
}
fclose(user);
}
}
else{
printf("Please enter correct username and password\n");
}
}
}
and let say in the user.txt the file is stored in a format like this
john;12/12/1990;[phone];57115
paul;12/12/1221;[phone];100022
max;12/11/1990;[phone];900000
jamie;12/05/2000;[phone];18000
Thank you

Answer 1

how do you read a data from a files and store it to an array, then read specific stored data in the array to be edited?
Steps to store data:
1) - Declare the type(s) of storage variables needed to support your concept. Array of struct perhaps.
2) - Open file ( FILE *fp = fopen("file path", "r"); )
3) - Loop on fgets() to read each line (record) of file
4) - Parse lines, perhaps using strtok and place elements of each line into storage variable you created above.
5) - close file ( fclose(fp); )
The get record part can be done by selecting a record, and returning a re-concatenated string composed of each field of the original record. The prototype could look like this:
void GetRecord(RECORD *pRec, int rec, char *recordStr);
Where storage would be created as an array of struct, and the struct would accommodate the 4 fields you cited, eg:
John;12/12/1990;[phone];57115 //example record with 4 fields
#define MAX_RECORDS 10 //arbitrary value, change as needed
typdef struct {
char name[260];
char date[11];
char num1;
char num2;
} RECORD;
RECORD record[MAX_RECORDS];//change size to what you need, 10 is arbitrary for illustration
Code Example to read data into records , and retrieve a record, could look like this:
(example only, very little error checking)
void GetRecord(RECORD *pRec, int rec, char *record);
int main(void)
{
FILE *fp = {0};
char recStr[260];
char *buf;
char line[260];
int i;
char strArray[3][7];//simple array, 3 string of 7 char each (enough for NULL terminator)
i = -1;
fp = fopen ("admin.txt", "r");
if(fp)
{
while (fgets (line, 260, fp))//will continue to loop as long as there is a new line
{
i++;
if(i >= MAX_RECORDS) break;//reached maximum records defined, time to leave
buf = strtok(line, ";");
if(buf)
{
strcpy(record[i].name, buf);
buf = strtok(NULL, ";");
if(buf)
{
strcpy(record[i].date, buf);
buf = strtok(NULL, ";");
if(buf)
{
record[i].num1 = atoi(buf);
buf = strtok(NULL, ";");
if(buf)
{
record[i].num2 = atoi(buf);
}
}
}
}
}
}
fclose(fp);
// 2nd argument valid values range from 1 - n (not 0 - n)
GetRecord(record, 3, recStr); //read third record into string "rec"
return 0;
}
void GetRecord(RECORD *pRec, int rec, char *record)
{
int r = rec - 1;//adjust for zero indexed arrays
if((r >= MAX_RECORDS) || (r < 0))
{
strcpy(record, "index error");
return;
}
sprintf(record, "%s;%s;%d;%d", pRec[r].name, pRec[r].date, pRec[r].num1, pRec[r].num2);
}
Note: "coz [you were] rushing and just copy the code, and accidentaly delete the important things",
I have not adhered strictly to your variable names. Adjust what I have done to meet your needs.
Results with your input file look like this: