putc

/*
 * call-seq:
 *   strio.putc(obj)    -> obj
 *
 * See IO#putc.
 */
static VALUE
strio_putc(self, ch)
    VALUE self, ch;
{
    struct StringIO *ptr = writable(StringIO(self));
    int c = NUM2CHR(ch);
    long olen;

    check_modifiable(ptr);
    olen = RSTRING(ptr->string)->len;
    if (ptr->flags & FMODE_APPEND) {
        ptr->pos = olen;
    }
    strio_extend(ptr, ptr->pos, 1);
    RSTRING(ptr->string)->ptr[ptr->pos++] = c;
    OBJ_INFECT(ptr->string, self);
    return ch;
}