how to write only one parameter in a file

[poison.summer]

Hello I need to write and read a parameter through a file to get
communication between two processes.
I know how to use fopen, fprintf. But I wonder how can I overwrite the
old files.
For instance, I need to write the value of A into a file. Another
process need to access the data of A.
Then the first process will overwrite the value of A.

How can I do that?

Thanks a lot!

 

[Logan Shaw]

Hello I need to write and read a parameter through a file to get
communication between two processes.
I know how to use fopen, fprintf. But I wonder how can I overwrite the
old files.
For instance, I need to write the value of A into a file. Another
process need to access the data of A.
Then the first process will overwrite the value of A.

Do a

rewind (file);

before you use fprintf() on the file.

- Logan

 

[Joe Wright]

Hello I need to write and read a parameter through a file to get
communication between two processes.
I know how to use fopen, fprintf. But I wonder how can I overwrite the
old files.
For instance, I need to write the value of A into a file. Another
process need to access the data of A.
Then the first process will overwrite the value of A.

How can I do that?

Thanks a lot!

As you have tried to do it, what problems do you have?

 

[abdur_rab7]

Hello I need to write and read a parameter through a file to get
communication between two processes.
I know how to use fopen, fprintf. But I wonder how can I overwrite the
old files.
For instance, I need to write the value of A into a file. Another
process need to access the data of A.
Then the first process will overwrite the value of A.

How can I do that?

Thanks a lot!

Insted of using files for giving communication between two process, you
can use either sockets or shared memory to do that

Best Regards,
Abdur

 

[Kenny McCormack]

Insted of using files for giving communication between two process, you
can use either sockets or shared memory to do that

Allow me to be the first to say this - and I say it from the deepness of my
heart, with all the kindness and love one has come to associate with the
helpful posts you get in this newsgroup:

Not portable. Can't discuss it here. Blah, blah, blah.

 

[Jack Klein]

Insted of using files for giving communication between two process, you
can use either sockets or shared memory to do that

The C language does not have sockets or shared memory. If your
platform does, it is a non-standard extension. And just because your
platform does, it does not mean that the OP's platform has the same
non-standard extensions.

And by the way, non-standard extensions are off-topic here.