Insert strings in array of string

Question

i have to insert strings in array of string in C. I wrote a function but it didn't work. Can you help me?

When i'm going to print the array, program crashes.

Thanks

int leggi(char **a, int *len) {
    int i;
    scanf("%d", len);
    if(*len <= 0) return 1;

    a = (char **) malloc(*len * sizeof(char *));
    if(a == NULL) return 1;

    for( i = 0; i < *len; i++ ) 
    {
        a[i]=(char *)malloc(101*sizeof(char));
        scanf("%s", &a[i]);
    }
    printf("Saved\n");
    return 0;
}

int main() {

    int i, n;
    char **A;

    if(leggi(A, &n)) return 1;
    printf("%d\n",n);




    for( i = 0; i < n; i++ ) 
    {
        printf("printf\n");
        printf("%s\n", &A[i]);
    }
    return 0;
}

What does "didn't work" means? What were the problems you noticed? — Cristik
– Cristik, Commented Apr 14, 2015 at 15:38
The malloc() must be cast! It returns a void* but i have char* and char**! — SimC
– SimC, Commented Apr 14, 2015 at 16:19
"malloc() must be cast": No, in C this is not necessary: stackoverflow.com/q/605845/694576 — alk
– alk, Commented Apr 14, 2015 at 16:20

Nazara · Accepted Answer · 2015-04-14 15:51:48Z

1

Change scanf("%s", &a[i]) to scanf("%s", a[i]), a[i] is the pointer to the first character in your string, getting the address of it would just return the address of the pointer, not the actual first char. Another thing to note is that you are not actually modifying the pointer in the main function, only the local function pointer, as such, it would have no effects on the one in main. Here's the edited version:

int read(char ***a, int *len) {
    int i;
    scanf("%d", len);
    if( *len <= 0 ) return 1;

    (*a) = (char **) malloc(*len * sizeof(char *));
    if((*a) == NULL) return 1;

    for( i = 0; i < *len; i++ )
    {
        (*a)[i]=(char *)malloc(101*sizeof(char));
        scanf("%s", (*a)[i]);
    }
    printf("Saved\n");
    return 0;
}

int main() {

    int i, n;
    char **A;

    if(read(&A, &n)) return 1;
    printf("%d\n",n);

    for( i = 0; i < n; i++ )
    {
        printf("printf\n");
        printf("%s\n", A[i]);
    }
    return 0;
}

edited Apr 14, 2015 at 15:51

answered Apr 14, 2015 at 15:38

Nazara

1244 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user3629249 Over a year ago

-1 because: this proposed answer still has most of the problems of the original posted code. 1) casting the returned call from malloc 2) naming the subroutine 'read()' 3) using 'sizeof(char)' note: sizeof(char*) is ok. 4) using "%s" as a format conversion parameter in scanf() means there is no size limit, so the user could enter enough characters to overflow the input buffer. 5) the returned value from scanf() is not being checked to assure the input/conversion was successful ...

Collectives™ on Stack Overflow

Insert strings in array of string

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related