Save, find and remove structure from txt file - c

Question

I am studying IT and programming is something new for me. Last week I got a task to do. I have to write a program which can save a structure (personal data of company's workers) to file.txt. Program should be able to find a specific person (putting his name or surname) and delete all people whose got a surname given by user as well. These all tasks should be in separate functions. Till now I wrote this function:
void struktura()
{
struct Person
{
char name[30];
char surname[30];
int age;
int height;
int weight;
};
int ile;
int i = 0;
printf("\n");
printf("How many persons would you like add to database (max 10 at once): ");
scanf("%d", &ile);
printf("\n");
if (ile >= 0)
{
printf("You added no one.\n");
}
else
{
struct Person *osoba[10]; //
while (i < ile)
{
osoba[i] = (struct Person*) malloc(sizeof (struct Person));
printf("Give a name: ");
scanf("%s", osoba[i]->name);
printf("Give a surname: ");
scanf("%s", osoba[i]->surname);
printf("Age: ");
scanf("%d", &osoba[i]->age);
printf("Height: ");
scanf("%d", &osoba[i]->height);
printf("Weight: ");
scanf("%d", &osoba[i]->weight);
printf("\n");
i = i + 1;
}
printf("You have added: \n\n");
i = 0;
while (i < ile)
{
printf("%d) Name: %s, Surname: %s, Age: %d years, Height: %d cm, Weight: %d kg.\n", i + 1, osoba[i]->name, osoba[i]->surname, osoba[i]->age, osoba[i]->height, osoba[i]->weight);
i = i + 1;
}
for (i = 0; i < ile; i++)
{
free(osoba[i]);
}
}
}
In additition, I have a code which save these persons to the file.txt. I would like to separate code (below) to another function but I don't know how to pass a structure to function.
FILE *save;
char name[30];
printf("\nWhere to save a database: ");
scanf("%s", name);
save = fopen(name, "a");
if (save == NULL)
{
printf("This file doesn't exist!");
getchar();
exit(1);
}
i = 0;
while (i < ile)
{
fprintf(save, "Name: %s, Surname: %s, Age: %d years, Height: %d cm, Weight: %d kg.\n",osoba[i]->name, osoba[i]->surname, osoba[i]->age, osoba[i]->height, osoba[i]->weight);
i = i + 1;
}
fclose(save);
I wrote a function, which opens the whole content of file.txt as well. What I missing is : how to find a specific person and how to delete these persons(I was thinking about opening a second temporary file and copy an content of original file except these lines which include given name/surname) (all in separate functions). Do you have any ideas how I could do this? I was looking for it in some books but I couldn't find any help.

Answer 1

I would like to separate code (below) to another function but I don't
know how to pass a structure to function.
Define struct Person outside and above the functions, so it can be used in all of them. Then you can put the code which saves the persons to the file in a function
void save(int ile, struct Person *osoba[ile])
{
…
}
and call this with
save(ile, osoba);
how to find a specific person
You could use the following function, which is a little more complicated than necessary for the finding task, but can be reused for another purpose:
char prformat[] =
"Name: %s, Surname: %s, Age: %d years, Height: %d cm, Weight: %d kg.\n";
char scformat[] =
"Name: %[^,], Surname: %[^,], Age:%d years, Height:%d cm, Weight:%d kg.\n";
// Read the data file "file.txt", look for 'name' or 'surname' (unless NULL),
// and output line(s) to 'out' if or unless they match (depending on 'match')
scan(char *name, char *surname, _Bool match, FILE *out)
{
FILE *fp = fopen("file.txt", "r");
if (!fp) perror("file.txt"), exit(1);
struct Person osoba;
while (fscanf(fp, scformat, osoba.name, osoba.surname,
&osoba.age, &osoba.height, &osoba.weight) == 5
)
if ( name && strcmp(osoba. name, name) == 0 == match
|| surname && strcmp(osoba.surname, surname) == 0 == match
)
if (fprintf(out, prformat, osoba.name, osoba.surname,
osoba.age, osoba.height, osoba.weight)
< 0) perror(""), exit(1);
fclose(fp);
}
calling it with
char name[30];
printf("Give a name or surname to find: ");
if (scanf("%29s", name) == 1)
scan(name, name, 1, stdout); // print matching lines to stdout
delete all people whose got a surname given by user …
(I was thinking about opening a second temporary file and copy an content of original file except these lines …
You were thinking right:
printf("Give a surname to delete: ");
if (scanf("%29s", name) == 1)
{
FILE *fp = fopen("file.tmp", "w");
if (!fp) perror("file.tmp"), exit(1);
scan(NULL, name, 0, fp); // print non-matching lines to tempfile
if (fclose(fp) < 0) perror("file.tmp"), exit(1);
remove("file.txt");
if (rename("file.tmp", "file.txt") != 0) perror("file.tmp");
}