Why is this program not printing on my file?

Question

This code is supposed to print the information entered by the user onto a file, but all it does is create an empty file...

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct room
{
    int room;
    char type[9];
    int cap;
    int price;
}rm;
FILE *k;
int main(){
    struct room rm;
    k=fopen("rooms.txt","w");
    printf("Please enter room number:");
    scanf("%d", rm.room);
    printf("\nPlease enter a description:");
    scanf("%s", rm.type);
    printf("\nPlease enter the room capacity:");
    scanf("%d", rm.cap);
    printf("\nPlease enter the price:");
    scanf("%d", rm.price);
    fprintf(k,"%d\t %s\t %d\t %d\n", rm.room,rm.type,rm.cap,rm.price);
    fclose(k);
}

Answer 1

Here

struct room
{
    int room;
    char type[9];
    int cap;
    int price;
}rm;

rm.room , rm.cap and rm.price are of int type, while scanning input from user, you need o provide the address & to store an integer into it. For eg Replace this

scanf("%d", rm.room); /* to store something into rm.room need to provide address */

with

scanf("%d", &rm.room);

and this

scanf("%d", rm.cap); /* address is not provided */
scanf("%d", rm.price); /* address is not provided */

with

scanf("%d", &rm.cap);
scanf("%d", &rm.price);

Also check the return type of fopen() . for eg

k=fopen("rooms.txt","w");
if(k == NULL) {
 /* @TODO error handling */
 fprintf(stderr, "failure message\n");
 return 0;
}

Answer 2

the following proposed code:

1. cleanly compiles
2. incorporates the comments to the question
3. performs the desired functionality
4. does not include header files those contents are not used
5. properly checks for errors
6. honors the printed page right margin
7. avoids any possibility of a buffer overflow and the resulting undefined behavior
8. remembers that a reference to an array degrades to the address of the first byte of the array
9. always passes an address as a parameter to function: scanf()
10. documents why each header file is included
11. separates the definition of a struct from an instance of a struct
12. does not declare an instance of the struct that is 'shadowed' by another instance of the struct with the same name
13. uses one of the valid signatures for function: main()

and now, the proposed code:

#include <stdio.h>   // fprintf(), fopen(), fclose(), perror(), scanf()
#include <stdlib.h>  // EXIT_FAILURE, exit()

struct room
{
    int room;
    char type[9];
    int cap;
    int price;
};


int main( void )
{
    struct room rm;

    FILE *k = fopen("rooms.txt","w");
    if( !k )
    {
        perror( "fopen rooms.txt for writing failed" );
        exit( EXIT_FAILURE );
    }

    printf("Please enter a room number:");
    if( scanf("%d", &rm.room) != 1 )
    {
        fprintf( stderr, 
                 "scanf for -room number- failed\n" );
        fclose( k );
        exit( EXIT_FAILURE );
    }

    printf("\nPlease enter a room description:");
    if( scanf("%8s", rm.type) != 1 )
    {
        fprintf( stderr, 
                 "scanf for -room description- failed\n" );
        fclose( k );
        exit( EXIT_FAILURE );
    }

    printf("\nPlease enter the room capacity:");
    if( scanf("%d", &rm.cap) != 1 )
    {
        fprintf( stderr, 
                 "scanf for -room capacity- failed\n" );
        fclose( k );
        exit( EXIT_FAILURE );
    }

    printf("\nPlease enter the room price:");
    if( scanf("%d", &rm.price) != 1 )
    {
        fprintf( stderr, 
                 "scanf for -room price- failed\n" );
        fclose( k );
        exit( EXIT_FAILURE );
    }

    // multi lined parameters to honor right page margin
    fprintf(k,"%d\t %s\t %d\t %d\n", 
        rm.room,
        rm.type,
        rm.cap,
        rm.price);
    fclose(k);
}

in answer to the OPs question: Why is this program not printing on my file?

Because nothing is being input by the posted code, due to the incorrect syntax for the scanf() function parameters