Question

I’m trying to strcat char *. However, I’ve noticed an issue.

struct d{
    struct d* up   //parent
    char *path     //path to d
    char *name     //path + breadth = name
}

for(j=0; j<b;j++){
    struct d* breadth_p;
    breadth_p=malloc(sizeof(struct d));
    char buffer[256];
    snprintf(buffer, sizeof(buffer), "/%d", j)   //prepares buffer to have "/j"
    breadth_p->up=cur_parent;
    breath_path->path=cur_parent->up->name;
    breadth_name=strcat(breadth->path, buffer);
    printf("name: %s\n", breadth_p->name);
    free(breadth_p);
}

so say I pass the cur_parent name and path as root and b as 3. the following prints out

root/0
root/0/1
root/0/1/2

I’m assuming that I didn’t free the breadth_p correctly so it’s concatenating the previous names.

the results I’m expecting is

root/0
root/1
root/2

Can anyone help me figure out why this is happening?

Answer 1

strcat() modifies in-place its first argument (appends the second argument to it) and then simply returns the modified input buffer. Read more about this behavior here.