如何从我创建的文本文件中读取结构？

Question

I'm writing C code for a program to simulate a patient database. I managed to write the code that add patient to the database and save the information to a text file.

The code that close the DB and saves the information to text file is down below and it works fine:

FILE *close_file;

close_file = fopen(file_name, "w");

if (close_file == NULL){
printf("save information to file failed!\n");
fclose(close_file);
exit(EXIT_FAILURE);
}

fprintf(close_file, "%d\n", *num_of_structs);/*Enters the number of the 
                                               patient in the DB in the 
                                              beginning of the text file*/

for (int j = 0; j < *num_of_structs;j++){

/*the for loop down below is to write referens number to the patients x- 
ray pictures, so the first two numbers in the text file belong to an array 
of two rooms*/

for (int picture = 0; picture < 2; picture++){
fprintf(close_file, "%d ", patientRegister[j].pictures[picture]);
}

/*down below I write the personal number and the name of the patient to 
the text file*/

fprintf(close_file, "%d %s", patientRegister[j].personal_number, 
patientRegister[j].patient_name);

}

fclose(close_file);

}

the text file can look like this: https://ibb.co/FKdx4vg

My problem is how to read from this text file? I tried a lot of code but without success. See my code which doesn't work for me except the line:

fscanf(existing_file, "%d", num_of_structs);/*This reads the first number 
at the top of the text file and which represents the number of patients in 
the DB*/

See the whole function that supposed to open a text file and read from it:

void open_existing_file(Patient patientRegister[], char file_name[], int 
*num_of_structs) {

FILE *existing_file;

existing_file = fopen(file_name, "r");

if (existing_file == NULL) {
printf("Open existing file failed\n");
fclose(existing_file);
exit(EXIT_FAILURE);
}


fscanf(existing_file, "%d", num_of_structs);/*This reads the first number 
at the top of the text file and which represents the number of patients in 
the DB*/

/*I guess I'm doing a lot of wrong code down here?!*/

for (int j = 0; j < (*num_of_structs); j++) {

for (int picture = 0; picture < 2; picture++) {
fscanf(existing_file, "%d", patientRegister[j].pictures[picture]);
}

fscanf(existing_file, "%d %s", patientRegister[j].personal_number, 
patientRegister[j].patient_name);}

fclose(existing_file);
}

Answer 1

The %d format specifier to scanf expects the address of an int , ie an int * , not an int . This is so it take the value it read and write it to the variable.

So you want:

fscanf(existing_file, "%d", &num_of_structs);
...
fscanf(existing_file, "%d", &patientRegister[j].pictures[picture]);
...
fscanf(existing_file, "%d %s", &patientRegister[j].personal_number, patientRegister[j].patient_name);

Note that you don't need & for %s to read into an array, since an array automatically decays to a pointer to its first element.