How can i fix segmentation fault in my code and what is the process I should follow to fix this in t-CodePudding

I'm a beginner to C and came across a segmentation fault, which is what I understand as to be the program trying to access restricted or unavailable area of memory.

This issue is occurring for me in a function:

void process_command(struct pizzeria *the_pizzeria, char *command) {
    if (command[0] == 'n') {
        struct order **last_next_order_field = get_last_next_order_field(the_pizzeria);
        *last_next_order_field = create_order();
    }

    if (command[0] == 's') {
        //Line below receives error
        get_integer_input(the_pizzeria->selected_order, "");
    }

}

which is linked to this other function:

void get_integer_input(int *variable, char *prompt) {
    printf(prompt);
    scanf("%d", variable);
    getchar();
}

It must be noted that these functions are relating to this struct:

#define PIZZERIA_NAME_LENGTH 16
#define PIZZERIA_OWNER_LENGTH 16

struct pizzeria {
   char name[PIZZERIA_NAME_LENGTH];
   char owner[PIZZERIA_OWNER_LENGTH];
   int selected_order;
   struct order *orders;

};

I don't understand why when passing the_pizzeria->selected_order in get_interger_input in the function process_command makes pointer from integer without a cast as in my past functions of getting a char input instead I use the same process and don't receive an error.

I also set variable as a pointer so I don't understand the note produced by the terminal:

note: expected ‘int *’ but argument is of type ‘int’

void get_integer_input(int *variable, char *prompt)

CodePudding user response：

You don't show us these "past functions", but I assume that they ask the user for name or owner. These elements of your struct are arrays, and if you pass their name as an argument it decays to a pointer to the first element.

In contrast, the integer is not an array. Therefore, you need to pass its address like this:

    if (command[0] == 's') {
        get_integer_input(&the_pizzeria->selected_order, "");
    }

If you are not very firm with operator precedence, better use parentheses:

    if (command[0] == 's') {
        get_integer_input(&(the_pizzeria->selected_order), "");
    }

The compiler is correct with its diagnostic message. You pass an integer, but the functions needs a pointer.