Concatenation In C

Question

Im creating an array of structs and i need to concatenate a string value with the for loop index.

this is how i create the struct:

typedef struct b
{
char title[30];
char author[40];
int year,price;

}
book_t;

then I create an array using malloc:

int m;
printf ("array size:\n");
scanf("%d",&m);
B= (book_t *) malloc (m*sizeof ( book_t));

and then i need to pass values to fill the array in this form: Title_i, Author_i, 1000+i, 3 * i for i=1...m so im using this for loop:

for(i=1;i<=m;i++){
    B[i-1].title='title_';
    B[i-1].author='author_';
    B[i-1].year=1000_i;
    B[i-1].price=3*i;
    }

any ideas on how can i get the i value of every loop next to the string value for the title and the author field?

How about itoa function? void* itoa(int input, char *buffer, int radix) — antonpp, Oct 20 '14 at 18:02
@Anton: That's neither C nor POSIX. BTW: [Don't cast the result of malloc (and friends)](http://stackoverflow.com/q/605845), character literals `'A'` are not string literals `"string"`. — Deduplicator, Oct 20 '14 at 18:04
@ Anton: if im running the first loop, i need the author field to be author_1, the second time author_2 etc. i dont want to convert int to ASCII. — Vivian, Oct 20 '14 at 18:09

Vlad from Moscow · Accepted Answer · 2014-10-20T18:09:49.950

3

Change this loop

for(i=1;i<=m;i++){
    B[i-1].title='title_';
    B[i-1].author='author_';
    B[i-1].year=1000_i;
    B[i-1].price=3*i;
    }

to

for ( i = 0; i < m; i++ )
{
    sprintf( B[i].title, "%s%d", "title_", i + 1 );
    sprintf( B[i].author, "%s%d", "author_", i + 1 );
    B[i].year = 1000 + i + 1;
    B[i].price = 3 * ( i + 1 );
}

I think that instead of 1000_i you mean 1000 + i + 1

edited Oct 20 '14 at 18:09

answered Oct 20 '14 at 18:03

Vlad from Moscow

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why supply `"title_"` as an arg to `sprintf` when it could have been in the format string? – Alnitak Oct 20 '14 at 18:14
1

@Alnitak I prefer the record I am using because instead of "title_" there can be any variable. That is it is a more general approach. – Vlad from Moscow Oct 20 '14 at 18:16

Concatenation In C

1 Answers1