Databases
StackOverflow2013
Postsdbo
POcreating an input function
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POcreating an input function
    primarykey
    data
    text
    <p>How do I create an input function that opens the input file and reads in the data from the file? And does that file have to be stored in a certain location? Can I do this just saving it on my desktop as a text file? This is what I have so far</p> <pre><code>#include &lt;stdio.h&gt; /* NULL is defined here */ #include &lt;stdlib.h&gt; /* for malloc() */ #include &lt;string.h&gt; /* for string related functions */ #define NAME_LEN 10 struct data { char name[NAME_LEN]; int age; int weight; }; typedef struct data DATA; struct linked_list { DATA d; struct linked_list * next; }; typedef struct linked_list ELEMENT; typedef ELEMENT * LINK; /* function prototypes */ LINK create_list_from_file(const char *); void print_list_to_file(LINK, const char *, const char *); int count(LINK, const int, const int); LINK lookup(const DATA, LINK); void insert(LINK, LINK, LINK); nt main(int argc, char *argv[]) { LINK head, found, to_add; char *in_file_name = "infile"; /* default input file name */ char *out_file_name = "outfile"; /* default output file name */ int a = 20, w = 150; /* will be used as the age limit and weight limit */ /* The input and output files can be given as command line arguments */ switch (argc) { case 1: printf("The default input and output files are %s and %s.\n", in_file_name, out_file_name); break; case 2: printf("The input file is %s and the default output file is %s.\n", argv[1], out_file_name); in_file_name = argv[1]; break; case 3: printf("The input file is %s and the output file is %s.\n", argv[1], argv[2]); in_file_name = argv[1]; out_file_name = argv[2]; break; default: printf("The input file is %s and the output file is %s.\n", argv[1], argv[2]); in_file_name = argv[1]; out_file_name = argv[2]; printf("The remaining arguments are not used.\n"); } /* 1. invoke create_list_from_file() function to create a linear linked list from the data in the input file, */ head = create_list_from_file(in_file_name); /* 2. invoke print_list_to_file() function with the writing mode ("w"), */ print_list_to_file(head, out_file_name, "w"); /* 3. invoke the count() function, 4. output the counted result to the screen, */ printf("The number of people with age over %d and weight over %d is %d.\n", a, w, count(head, a, w)); /* 5. invoke the lookup() function and insert() function, and */ /* prepare an element to be looked-up and added */ to_add = malloc(sizeof(ELEMENT)); strcpy(to_add -&gt; d.name, "Janet"); to_add -&gt; d.age = 21; to_add -&gt; d.weight = 150; to_add -&gt; next = NULL; found = lookup(to_add -&gt; d, head); insert(head, found, to_add); /* 6. invoke print_list_to_file() function with the append mode ("a"). */ print_list_to_file(head, out_file_name, "a"); /* repeat step 5 with an element that does not exist in the current list */ /* prepare an element to be looked-up and added */ to_add = malloc(sizeof(ELEMENT)); strcpy(to_add -&gt; d.name, "Jerry"); to_add -&gt; d.age = 24; to_add -&gt; d.weight = 220; to_add -&gt; next = NULL; found = lookup(to_add -&gt; d, head); insert(head, found, to_add); /* repeat step 6: invoke print_list_to_file() function with the append mode ("a"). */ print_list_to_file(head, out_file_name, "a"); return 0; } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USDan D.
    1. USJacob
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POcreating an input function
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    1. COThe file doesn't have to be in a specific location. Just Google "C file read example" and you will find plenty of examples. The code above has nothing to do with reading files.
      singulars
      1. POcreating an input function
      1. USJoel Lee
    2. COsorry, posted the wrong code
      singulars
      1. POcreating an input function
      1. USJacob
    3. CO@jonsca: That's not true, `in_file_name` is a `char *`, and can certainly point to `argv[1]`.
      singulars
      1. POcreating an input function
      1. USGreg Hewgill
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload