fprintf segfault

I am trying to pratice c programming, i am trying to write a very simple program that would record a order and write it to a text file, problem is the program crashes when trying to use fprintf.

I have changed the fprintf line to print on stdout and it works, but not for a file.

Here is the code


[C] order c program - Pastebin.com

This is happening on both my desktop(linux), and my android phone(using c4droid)

Please help me, much appreciated

Compile with some more warnings.

Code:

$ gcc -Wall bar.c
bar.c: In function ‘ask_order’:
bar.c:50: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:55: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:60: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:64: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:65: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:66: warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’
bar.c:77: warning: format ‘%s’ expects type ‘char *’, but argument 3 has type ‘char **’
bar.c:77: warning: format ‘%s’ expects type ‘char *’, but argument 4 has type ‘char **’
bar.c:77: warning: format ‘%s’ expects type ‘char *’, but argument 5 has type ‘char **’

Your struct is definitely not what you think it is.

Nor do you check that the file was opened
orderfile = fopen("order.txt", "w");
Where is
if ( orderfile == NULL )

Please post your code in your post between code tags.

Code:

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

int i = 0;

typedef struct
{

	char *entree[80];
	char *drink[80];
	char *dessert[80];

} order;

void print_commands()
{
	printf("e: entree\n");
	printf("d: drink\n");
	printf("t: dessert\n");
	printf("o: print complete order\n");
	printf("c: print list of commands\n");
	printf("w: write to text file\n");
	printf("x: exit\n");
}


void ask_order()
{


	char choice;
	order o;
	FILE *orderfile = NULL;
	orderfile = fopen("order.txt", "w");

	printf("Welcome\nWhat Would you like to order?:\n");
	printf("Commands:\n\n");
	print_commands();
	while (i == 0)
	{
		printf("\nENTER_OPTION>");
		scanf("%c", &choice);
		switch (choice)
		{

		case 'e':

			printf("Enter your entree: ");
			scanf("%s", o.entree);
			break;

		case 'd':
			printf("Enter your drink: ");
			scanf("%s", o.drink);
			break;

		case 't':
			printf("Enter a dessert: ");
			scanf("%s", o.dessert);
			break;

		case 'o':
			printf("Entree: %s\n", o.entree);
			printf("Drink: %s\n", o.drink);
			printf("Dessert: %s\n", o.dessert);
			break;

		case 'c':
			print_commands();
			break;

		case 'w':
			printf("Saving to File...\n");
			/* This isnt Working, it segfaults... */
			fprintf(orderfile, "Entree: %s\nDrink: %s\nDessert: %s\n",
					o.entree, o.drink, o.dessert);
			fclose(orderfile);
			break;

		case 'x':

			i += 1;
			break;


		}
	}
}


int main()
{
	ask_order();
	return 0;
}

First I recommend you increase your compiler warning level, here are the warnings I received when compiling your code:

main.c||In function ‘ask_order’:|
main.c|50|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|55|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|60|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|64|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|65|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|66|warning: format ‘%s’ expects type ‘char *’, but argument 2 has type ‘char **’|
main.c|77|warning: format ‘%s’ expects type ‘char *’, but argument 3 has type ‘char **’|
main.c|77|warning: format ‘%s’ expects type ‘char *’, but argument 4 has type ‘char **’|
main.c|77|warning: format ‘%s’ expects type ‘char *’, but argument 5 has type ‘char **’|
main.c|44|warning: switch missing default case|

Where do you ever allocate memory for your pointers contained in your structure? Why do you even have those pointers?

Jim

thank you guys, i got it working now,
i got rid of the pointers and made them simple strings,
interstingly at first i was able to fix it by changing the write mode to "a+"
but i had a lot of warnings so i fixed the code, and now it works fine

i feel more confident on how to write to files, thank you guys

here is the code:

Code:

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

int i = 0;

typedef struct {
    
    char entree[80];
    char drink[80];
    char dessert[80];

} order;

void print_commands()
{
    printf("e: entree\n");
    printf("d: drink\n");
    printf("t: dessert\n");
    printf("o: print complete order\n");
    printf("c: print list of commands\n");
    printf("w: write to text file\n");
    printf("x: exit\n");
}


void ask_order()
{
    
    order o;
    char choice;
    FILE *file;
     
    printf("Welcome\nWhat Would you like to order?:\n");
    printf("Commands:\n\n");
    print_commands();
    while (i == 0) {
    printf("\nENTER_OPTION>");
    scanf("%c", &choice);
    switch(choice) {
        
        case 'e':

            printf("Enter your entree: ");
            scanf("%s", o.entree);
            break;
    
        case 'd':
            printf("Enter your drink: ");
            scanf("%s", o.drink);
            break;

        case 't':
            printf("Enter a dessert: ");
            scanf("%s", o.dessert);
            break;
        
        case 'o':
            printf("Entree: %s\n", o.entree);
            printf("Drink: %s\n", o.drink);
            printf("Dessert: %s\n", o.dessert);
            break;

        case 'c':
            print_commands();
            break;
            
        case 'w':
            printf("Saving to File...\n");
            file = fopen("order.txt", "w");
            if (file == NULL)
            {
                fprintf(stderr, "Error Creating File\n");
            }
        fprintf(file, "Entree: %s\nDrink: %s\nDessert: %s\n", o.entree, o.drink, o.dessert);
            fclose(file);
            break;

        case 'x':
            
            i += 1;
            break;
    
            
    }
}
}
    

int main()
{
    ask_order();
    return 0;
}

sorry for not using code tags before, , i was working with this on my smart phone, i was going to post it somewhere else, but it wasnt working so i iused pastebin and didnt feel like copying and pasting it all
again, its kinda annoying on my smartphone, plus i was really tired and probally wasnt thinking to
bright...