Thread: Writting a struct to a file

Hi, I am trying to write a structure to a file. Example say the structure has two variables x and y . I want to write a function which modifies these variables and stores the modified version on a file. Such that next time I call the function . it has the values from the previous write.

Here's an example of my code .

Code:

// initialize the structure struct->x = 0, struct->y = 0

File *fp = fopen("filename", "r+");
struct MYSTRUCT mystruct = (struct MYSTRUCT*)malloc(sizeof(MYSTRUCT))
//check 
fread (mystruct, sizeof(MYSTRUCT), 1, fp);

// do some calculations.

fwrite(mystruct, sizeof(MYSTRUCT), 1, fp);

fclose(fp)

//return some value
}

The problem is that each time I run the program it shows the initialized value of the variables and not the value from last write. I guess the write isn't successful because when I open in w+ mode. i get the error file could not be opened and then i have to delete the file and re create it

You should probably also be using the binary open mode as well.

Jim

It worked. Thanks a lot