fopen manipulation (in C)

[odin607]

Please respond with answers in C.

Alright so lets say we have a structure:

typedef struct
{
    char Item[5];
    char Descript[7];
} INFO;
 

Then lets say we fill it:

strcpy(INFO.Item,"A01");
strcpy(INFO.Descript,"DA01");
 

How would i then open a file using the string within INFO.Descript?

To show what i mean..(assume the file named DA01.txt exists)

fopen( "[string within INFO.Descript].txt" , "r"); //psuedo code

[oler1s]

Your code won’t work. INFO is not a variable. It’s a typename. Look at what that typedef is doing. In any case, the concept you are looking for is string concatenation. There’s a function for that in C. It’s strcat. Or strncat.

[odin607]

the last line is psuedo code as the comment says, of course it doesnt work

I'll ask the same question in another way.

I need to open a file which is dependent on the value of INFO.Descript

if Descript is aa0001 i need it to open file aa0001.txt
if Descript is ab1234 i need it to open file ab1234.txt
etc..

[oler1s]

I’ll explain again.

the last line is psuedo code as the comment says, of course it doesnt work

Sure, but I wasn’t talking about the last line. When you do something like INFO.Descript, you treat INFO as a variable. It’s not a variable. INFO is the name of a new type you created (the struct). Do you see a problem with your code now?

if Descript is aa0001 i need it to open file aa0001.txt
if Descript is ab1234 i need it to open file ab1234.txt
etc..

Yes. What you are doing is concatenating “.txt” to some string. String concatenation.

[odin607]

ah, well assume i had made INFO INFO

so how would i then open the file once the file name in INFO.Descript

[oler1s]

so how would i then open the file once the file name in INFO.Descript

Concatenate the file extension onto the file name, then pass the augmented filename as a parameter to fopen. You already have the idea. Google C string concatenation, variations included, as well as look up strcat and strncat which I mentioned previously. There’s plenty of articles that show you code and theory for C string concatenation.

The basic principle is that you ensure your target string is big enough to hold the file extension. If it isn’t, you need to get a bigger set of space. Then use strcat or strncat to append to your target string.

[Atos]

<Solution Snipped>

I think that comments cover the most part...

[Banfa]

Sorry Atos I have removed your solution to the problem. I would suggest you take a moment to read our Posting Guidelines. Particularly "How to respond to a question" which explains why we do not allow full code solutions on the site.

Banfa
Voice of Reason (and Administrator)

[Atos]

Sorry Atos I have removed your solution to the problem. I would suggest you take a moment to read our Posting Guidelines. Particularly "How to respond to a question" which explains why we do not allow full code solutions on the site.

Banfa
Voice of Reason (and Administrator)

if you had taken a moment to read my code you would have seen that it was a "explanatory" code and this was it's purpose. To show a way to solve a problem. Besides it was only a function.

If you think that by only reading books and writing code and NOT by READING CODE then...... ( i don't really have to say anything )

[r035198x]

if you had taken a moment to read my code you would have seen that it was a "explanatory" code and this was it's purpose. To show a way to solve a problem. Besides it was only a function.

If you think that by only reading books and writing code and NOT by READING CODE then...... ( i don't really have to say anything )

The problem is that you broke the site rules by posting a "full code solution". I agree that reading code helps a lot when learning but the site rules do not permit posting of full code solutions (also known as spoon-feeding).

[odin607]

yes and if you dont spoon feed a baby, itll die...

same deal with me, except not as morbid... i still dont know the solution because that was removed =p.. actually stopped making the program cause of this.. and got tired of having to ask 3000 questions/minute

but none the less if an answer could be sent to me (spoon fed or not) that would be awesome.. add it to the library of weird things I know how to do list.