another c project

**thenewbiecoder** · 07-07-2009

hi all, gotta solve a problem: this is a project called post_office, his aim is to simulate insertion and shipment of postal products from different cities (cases a and b) and show information about cities and products in their shipping list (case c)

the problem is that in case b whatever string I put it doesn't ship anything.

it seems there's a problem with the for cycle (line 166), but I really don't catch it.

I hope someone here could help me, this is the code

C pastebin - collaborative debugging tool

**whiteflags** · 07-08-2009

Have you done any debugging with your IDE's tools?

**quzah** · 07-08-2009

Code:

#typedef struct a_city{
#        int cod_num;
#        char name[15];
#        char pos[7];
#        char cap[6];
#    product listprod[MAX_PRODOTTI];
#        int num_prod;
#}city;
#
#//dati delle citta'
#char city_data [CITTA*3][15]={  "Avellino","Sud","83100",
#                            "Benevento","Sud","82100",
#                            "Firenze","Centro","50100",
#                            "Genova","Nord","16100",
#                            "Milano","Nord","20100",
#                            "Napoli","Sud","80100",
#                            "Perugia","Centro","06100",
#                            "Roma","Centro","00100",
#                            "Torino","Nord","10100",
#                            "Venezia","Nord","30100"};

This would be better if you made 'city' its own structure, and then made another one that had a city + its product.

Code:

typedef struct a_city{
        int cod_num; /* remove this if it's not actually something relevant, and stick it in the other structure */
        char name[15];
        char pos[7];
        char cap[6];
} cityinfo;

typedef struct productioninfo {
    cityinfo thiscity;
    product listprod[MAX_PRODOTTI];
    int num_prod;
} cityproduction;

That way, the whole problem you are having with swapping citys around would be much easier to fix. Plus, your city list would instead look like:

Code:

cityinfo cities[] = {
    { /*whatever that number is... or remove it */ 5, "Benevento","Sud","82100", },
    ...the rest of the cities...
};

Quzah.

**thenewbiecoder** · 07-08-2009

Originally Posted by whiteflags

Have you done any debugging with your IDE's tools?

no I didn't... I use vi+gcc but I can also use CodeBlocks, what should I do to debug?

do you mean to use assert o what?

sorry for my lack of experience

**thenewbiecoder** · 07-08-2009

the problem presents itself only when we have to ship the LAST product in the shipping cue; so it seems to be related to the fact that when I put
strcpy(city[i-1].listprod[j].type,city[i-1].listprod[j+1].type);
it finds nothing on j+1; should I inizialize all city[i].listprod[j].type to NULL to solve it?

edit it doesn't work... please help me

**whiteflags** · 07-08-2009

Originally Posted by thenewbiecoder

no I didn't... I use vi+gcc but I can also use CodeBlocks, what should I do to debug?

do you mean to use assert o what?

sorry for my lack of experience

Learn about breakpoints and watching variables at least under CodeBlocks.... being able to watch your own programs execute under test data is the key to ensuring that they work correctly. It also helps you ask more competent questions here after you're really stuck. A lot of the time, just watching code execute, you can fix your own problems.

the problem presents itself only when there's one single product in shipping list; so it seems to be related to the fact that when I put
strcpy(city[i-1].listprod[j].type,city[i-1].listprod[j+1].type);
it finds nothing on j+1; should I inizialize all city[i].listprod[j].type to NULL to solve it?

Dereferencing NULL will cause undefined behavior in your program, so your suggestion is not safe.

I think you need to restructure some of the data you use, like quzah said, to fix this appropriately. If you're having trouble staying within the bounds of your arrays something is far too complicated.

**quzah** · 07-08-2009

You should be initializing your product list to have nothing in it before you start using. You're still over complicating this with all the string swapping and such. Why don't you just have a product list and store a list of products by number, rather than swapping string all around? Same thing with cities.

Code:

struct productinfo {
    char *productname;
    int productvalue;
    int whatevercrapyoufeellikeputtingin;
};

struct {
    int product;
    int quantity;
} productinfo;

struct cityproduction {
    int citynumber;
    struct productinfo productlist[ MAXPRODUCTS ];
};

Now you'd pretty much have to rewrite the whole thing here, but it would be a lot cleaner. Build a list of all your products. Build a list of all your cities. Reference cities by their number in their table, and products the same way. There are a lot of variations on the theme you could do here. But I'm not sure that you need to keep swapping strings all over the place, when numbers are much easier to swap and deal with.

Quzah.

**thenewbiecoder** · 07-08-2009

solved it, thanks anyway to all of you that gave me suggestions but I really didn't ask how to optimize the code, I just had a problem with a code that I needed to complete in two hours

the solution was a simple if ^_^

Code:

for(j=0;j<city[i-1].num_prod;j++){
                                if((j==city[i-1].num_prod-1) && (strcmp(prodotto,city[i-1].listprod[j].type)==0)){
                                        city[i-1].num_prod=city[i-1].num_prod-1; //decrementa il totale dei prodotti in spedizione
                                        printf("\nProdotto spedito con successo!\n\n");
                                }
                                else if((j!=city[i-1].num_prod-1) && (strcmp(prodotto,city[i-1].listprod[j].type)==0)){
                                    for(;j<city[i-1].num_prod-1;j++){ //non inizializza j, utilizza il valore incrementato dall'altro ciclo
                                        city[i-1].listprod[j].code_n=city[i-1].listprod[j+1].code_n;
                                        strcpy(city[i-1].listprod[j].type,city[i-1].listprod[j+1].type);
                                        city[i-1].listprod[j].prezzo=city[i-1].listprod[j+1].prezzo;
                                        city[i-1].num_prod=city[i-1].num_prod-1; //decrementa il totale dei prodotti in spedizione
                                        printf("\nProdotto spedito con successo!\n\n");
                                    }
                                }
                                else if((j==city[i-1].num_prod-1) && (strcmp(prodotto,city[i-1].listprod[j].type)!=0)){
                                    printf("\nProdotto non trovato.\n\n");
                                }
                            }

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