Can I save a structure in a file, e.g txt.file?

Question

Can I save a structure in a file, for example to a txt?. And also if I can, would it be possible to reopen it and get the data back?

Maybe something like this:

struct guest
{
        int tel;
        char name[20];
        char country[20];
} ;

int main()
{

        record.tel=231231;
        strcpy(record.name, "Raju");
        record.country= China;

You can - just define a standard way to store it and then retrieve it using the same method. — Filipe Gonçalves, Jan 20 '14 at 12:00
You can. But you most likely don't want to. You want to store this stuff in a database instead. If you haven't any database handy, pick sqlite. — pentadecagon, Jan 20 '14 at 12:05

user3125367 · Answer 1 · 2014-01-20T12:07:44.677

fprintf(file, "%d %20s %20s\n", record.tel, record.name, record.country);
fscanf(file, "%d %20s %20s\n", &record.tel, &record.name, &record.country);

UPD: if name and/or country may contain spaces, use the following to read back:

char blank[1];

fscanf(file, "%d ", &record.tel);
fread(record.name, 20, 1, file);
fread(blank, 1, 1, file); // assert(blank[0] == ' ');
fread(record.country, 20, 1, file);
fread(blank, 1, 1, file); // assert(blank[0] == '\n');

score 1 · Answer 2 · edited May 23 '17 at 11:49

1

Functionality you describe is called serialization.
There are a lot of information in the internet. for ex. refer to the:
Data serialization in C?

edited May 23 '17 at 11:49

Community

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answered Jan 20 '14 at 12:05

spin_eight

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score 1 · Accepted Answer · answered Jan 20 '14 at 12:10

Basically you can. You have two choises.

1) As a binary that is not portable.

//  Writing to a file inticaded by fp ...
fwrite( &record, sizeof(struct guest), 1, fp );

// Reading from a file inticaded by fp ... 
fread( &record, sizeof(struct guest), 1, fp );

2) As a text, which is portable.

//  Writing to a file inticaded by fp ...
fprintf( fp, "%d %20s %20s", record.tel, record.name, record.country );

// Reading from a file inticaded by fp ... 
fscanf( fp, "%d %s %s", &record.tel, &record.name, &record.country );

With first choice (binary) you can read directly from the file, see an example here, if you save it as a text you will have to read line by line and give values manually in the fields of the struct.

Thanks for the explanation and the link, that helped a lot. – Jan 20 '14 at 12:13 — , Jan 20 '14 at 12:13

score 1 · Answer 4 · answered Jan 20 '14 at 12:17

1

If its your first time use fprintf() / fscanf() and no printf() / scanf()

answered Jan 20 '14 at 12:17

Can I save a structure in a file, e.g txt.file?

4 Answers4