public class ShoppingList{
String store;
int noItems;
String[]itemNames;
int [] itemCounts;
ShoppingList(){
store="";
noItems=0;
itemNames=new String [100];
itemCounts= new int [100];
}
ShoppingList(String str, int no){
store=str;
noItems=no;
}
public String [] addItem(String article, int number ){
for(int i=0; i<itemNames.length-1; i++){
itemNames[i]=article;
itemCounts[i]=number;
}
return itemNames;
}
public int noTotalItems(){
int anzahl=0;
noItems=anzahl;
for(int m=0; m<itemCounts.length-1; m++){
anzahl=anzahl+itemCounts[m];
}
return anzahl;
}
public int getNumberOf(String produkt){
int zahl=0;
for(int k=0; k<itemNames.length-1; k++){
if(itemNames[k]==produkt){
zahl=itemCounts[k];
return zahl;
}
}
return zahl;
}
public String [] toString(ShoppingList l){
return itemNames;
}
}
**public class ShoppingListTest{
public static void main (String [] args){
ShoppingList l=new ShoppingList("Supermarkt", 100);
l.addItem("Prosecco", 3);
l.addItem("Milk", 4);
l.addItem("Wine", 5);
l.addItem("Eggs", 4);
Out.println(l);
Out.println("#total items: "+l.noTotalItems());
Out.println("#Milk: "+l.getNumberOf("Milk"));
Out.println("#Wine: "+l.getNumberOf("Wine"));
}
}**
Hi guys! I would be really thankful, if you can help me to solve my problem. This is my code with all classes, but when I compile the ShoppingListTest, I get the following Error: "Exception in thread "main" java.lang.NullPointerException
at ShoppingList.addItem(ShoppingList.java:25)
at ShoppingListTest.main(ShoppingListTest.java:5)"
I am not allowed to create Lists I have to add the items to the String array"itemNames".
This line: ShoppingList(String str, int no){ needs to change to: ShoppingList(String str, int no) { this(); // <-- HERE.
Basically, in your test you are using a construct which does not initialise the required arrays, thus causing them to be null.
Calling this(), in your parametrized constructor will call the parameterless constructor you have, which in turn, initialises the required arrays and other variables.
Related
So I recently started with C at exercism page.
I currently facing a rather simple challenge.
Determine if a word or phrase is an isogram.
An isogram (also known as a "non-pattern word") is a word or phrase without a repeating letter, however spaces and hyphens are allowed to appear multiple times.
Examples of isograms:
lumberjacks
background
downstream
six-year-old
The word isograms, however, is not an isogram, because the s repeats.
There are 15 tests in total, of which one specific is not passed:
test_isogram_with_duplicated_hyphen
I guess test number 15 also passes because of some error I don't see
Here's the testing code:
#include "test-framework/unity.h"
#include "isogram.h"
#include <stdlib.h>
void setUp(void)
{
}
void tearDown(void)
{
}
static void test_empty_string(void)
{
TEST_ASSERT_TRUE(is_isogram(""));
}
static void test_null(void)
{
TEST_IGNORE(); // delete this line to run test
TEST_ASSERT_FALSE(is_isogram(NULL));
}
static void test_isogram_with_only_lower_case_characters(void)
{
TEST_IGNORE();
TEST_ASSERT_TRUE(is_isogram("isogram"));
}
static void test_word_with_one_duplicated_character(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("eleven"));
}
static void test_word_with_one_duplicated_character_from_end_of_alphabet(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("zzyzx"));
}
static void test_longest_reported_english_isogram(void)
{
TEST_IGNORE();
TEST_ASSERT_TRUE(is_isogram("subdermatoglyphic"));
}
static void test_word_with_duplicated_letter_in_mixed_case(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("Alphabet"));
}
static void test_word_with_duplicated_letter_in_mixed_case_lowercase_first(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("alphAbet"));
}
static void test_hypothetical_isogrammic_word_with_hyphen(void)
{
TEST_IGNORE();
TEST_ASSERT_TRUE(is_isogram("thumbscrew-japingly"));
}
static void
test_hypothetical_word_with_duplicated_character_following_hyphen(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("thumbscrew-jappingly"));
}
static void test_isogram_with_duplicated_hyphen(void)
{
TEST_IGNORE();
TEST_ASSERT_TRUE(is_isogram("six-year-old"));
}
static void test_made_up_name_that_is_an_isogram(void)
{
TEST_IGNORE();
TEST_ASSERT_TRUE(is_isogram("Emily Jung Schwartzkopf"));
}
static void test_duplicated_character_in_the_middle(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("accentor"));
}
static void test_same_first_and_last_characters(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("angola"));
}
static void test_word_with_duplicated_character_and_with_two_hyphens(void)
{
TEST_IGNORE();
TEST_ASSERT_FALSE(is_isogram("up-to-date"));
}
int main(void)
{
UnityBegin("test_isogram.c");
RUN_TEST(test_empty_string);
RUN_TEST(test_null);
RUN_TEST(test_isogram_with_only_lower_case_characters);
RUN_TEST(test_word_with_one_duplicated_character);
RUN_TEST(test_word_with_one_duplicated_character_from_end_of_alphabet);
RUN_TEST(test_longest_reported_english_isogram);
RUN_TEST(test_word_with_duplicated_letter_in_mixed_case);
RUN_TEST(test_word_with_duplicated_letter_in_mixed_case_lowercase_first);
RUN_TEST(test_hypothetical_isogrammic_word_with_hyphen);
RUN_TEST(test_hypothetical_word_with_duplicated_character_following_hyphen);
RUN_TEST(test_isogram_with_duplicated_hyphen);
RUN_TEST(test_made_up_name_that_is_an_isogram);
RUN_TEST(test_duplicated_character_in_the_middle);
RUN_TEST(test_same_first_and_last_characters);
RUN_TEST(test_word_with_duplicated_character_and_with_two_hyphens);
return UnityEnd();
}
This is my code:
#include "isogram.h"
#include <stdlib.h>
#include <stdio.h>
/* gives new char array from input, only small letters */
char* clean_words(char* ptr_input)
{
// new container; everything bigger than 27 is impossible to be an isogram
static char cleaned[27] = {"00000000000000000000000000"};
int i = 0, j = 0, k = 0;
for (int i = 0; ptr_input[i] != '\000'; i++)
{
k++;
}
for (i=0; i <= k; i++, j++)
{
if (ptr_input[i] > 64 && ptr_input[i] < 91)
{
cleaned[j] = ptr_input[i] + 32;
}
else if (ptr_input[i] > 96 && ptr_input[i] < 123)
{
cleaned[j] = ptr_input[i];
}
else
{
j--;
}
}
char* ptr_output = &cleaned[0];
return ptr_output;
}
bool is_isogram(char phrase[])
{
if(phrase == NULL)
{ return false; }
char* ptr_a = clean_words(phrase);
char ca_empty[27] = {"00000000000000000000000000"};
for(int i = 0; i <= 27; i++, ptr_a++){
// first element is always copied
if(i == 0){
ca_empty[i] = *ptr_a;
continue;
}
// '0' is sentinel, meaning the input word is finished => exit loop.
if(*ptr_a == '0' || *ptr_a == '\000')
{ break; }
// following elements only copied if different than current input char
int j = 0;
// loop copied for doubles, exit when found
for(;j<i;j++)
{
if(ca_empty[j] == *ptr_a){
return false;
}
}
// if none was found, copy new letter
ca_empty[i] = *ptr_a;
}
return true;
}
So basically I solve this in 2 steps. First, I will reduce any input to small letters only. Second, I copy letter by letter to a new container and test doubles before every copy process.
Yes, there are certainly fancier solutions, but I'd like to know if anyone can spot why I get FAILED on "six-year-old". Especially, when it is working locally. Thanks! :-)
So I figured it out by myself:
The problem is the helper function clean_words.
The char array cleaned is declared as static. That means it will keep its value even after the current block is finished.
When the tests run through, cleaned will still contain remaining letters of the input from other tests. The solution would be removing the static keywird or implementing a way to clean up the container, like
memset(cleaned, '0', 26);
From https://en.cppreference.com/w/c/language/storage_duration
static storage duration.
The storage duration is the entire execution of the program, and the value stored in the object is initialized only once, prior to main function. All objects declared static and all objects with either internal or external linkage that aren't declared _Thread_local (since C11) have this storage duration.
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Question:
I want to create a reusable function, because in my code much line that use same code structure
The code using for example if { if { `Only here's the different` } }. Of course the pattern not same as this, this using as an example.
I've been code using framework such as Laravel, there's a directive called as SLOT
Is there any way I can inject code in the middle of for loop? Or anything same as SLOT inside C programming
Sample code:
void functionname() {
for (int i=0; i < total_count; i++) {
SELECT THE ITEM (i)
if (a == b) return;
if (c) {
CODE INJECT HERE
}
}
}
Forget to mention before, a, b, c and so on from the coding above is getting from ITEM (i)
You should use a callback. i.e. you should send a function pointer (i.e. the address of the function you want to execute) and use that pointer to execute that function inside your loop.
In the example below, p is a pointer to a function taking a const char * for a parameter and returning an int.
int (*p)(const char *s) ;
NB: all functions passed as parameter, to be used as callback must have the same prototype (which is why such functions are often declared taking a generic pointer parameter void * to accept whatever you've got to send to the function).
So with your example and with functions taking void * as a parameter and returning void *, and with param defining a parameter that you want to feed to your function, this gives us the following code:
void functionname(void *(*func)(void *)) {
for (int i=0; i < total_count; i++) {
SELECT THE ITEM (i)
if (a == b) return;
if (c) {
func(¶m);
}
}
}
you can call your function wiht whatever function respecting the prototype... For instance:
void *my_custom_function(void *param) {
...
}
...
functionname(my_custom_function);
...
As suggested in the comment by KamilCik, use function pointers:
void functionname(void *fx)(void)) {
for (int i=0; i < total_count; i++) {
SELECT THE ITEM (i)
if (a == b) return;
if (c) {
//CODE INJECT HERE
fx();
}
}
}
And use it like
void foo(void) { puts("foo() called"); }
void bar(void) { puts("bar() called"); }
int main(void) {
functionname(foo);
functionname(bar);
}
For a concrete example:
#include <stdio.h>
int a = 1;
int b = 2;
typedef void (*selector)(int, int *);
typedef void (*injector)(void);
void select1(int x, int *c) { printf("%s: %d\n", __func__, *c = x); }
void select2(int x, int *c) { printf("%s: %d\n", __func__, *c = x); }
void inject1(void) { printf("%s\n", __func__); }
void inject2(void) { printf("%s\n", __func__); }
void
functionname(size_t total_count, selector SELECT_THE_ITEM,
injector CODE_INJECT_HERE )
{
for (size_t i=0; i < total_count; i++) {
int c;
SELECT_THE_ITEM (i, &c);
if (a == b) return;
if (c) {
CODE_INJECT_HERE();
}
}
}
int
main(void)
{
functionname(2, select1, inject1);
functionname(3, select2, inject2);
}
You can do what you ask by defining your "CODE INJECT HERE" as the body of a function, and passing a pointer to that function:
void functionname(void (*inject)(void)) {
for (int i=0; i < total_count; i++) {
SELECT THE ITEM (i)
if (a == b) return;
if (c) {
inject();
}
}
}
void do_something(void) {
CODE INJECT HERE
}
void do_something_else(void) {
OTHER CODE INJECT HERE
}
int main(void) {
functionname(do_something));
functionname(do_something_else));
}
Do note, however, that this is not simple code injection in the same sense as a macro would provide. In particular, the executions of do_something() and do_something_else() will not see the local variables of main() or of functionname(), and the do_* functions can return only from themselves, not from a caller further up the chain. The former can be mitigated to some extent by passing parameters to the do_* functions (which they must be prepared to accept).
Another alternative would be to use a macro instead of a function to provide the common framework. It would look something like this:
#define frame_it(x) do { \
for (int i=0; i < total_count; i++) { \
SELECT THE ITEM (i) \
if (a == b) return; \
if (c) { \
x \
} \
} \
} while (0)
int main(void) {
frame_it(
CODE INJECT HERE
);
frame_it(
OTHER CODE INJECT HERE
);
}
That keeps the CODE INJECT HERE code in the function using it, which might be advantageous if in fact each such piece of code is used in only one place. It also allows both that code and the framing code to access the local variables of the function in which they appear, and to return from that function if desired.
However, macro programming has earned a mostly-deserved reputation for being error prone and difficult to read and debug. Your particular need may be one that is well served by this approach, but do not choose this direction lightly.
Function pointers are great for this. You can typedef the function signatures you'd like to support. Example:
/* A signature for condition checking functions, taking a "void*" argument
and returning true or false */
typedef bool(*cond_check_t)(void*);
/* A signature for functions to execute if a condition is met. This takes a
"void*" argument but you decide what you need */
typedef void(*exec_t)(void*);
You can package these two in a struct to form a nice pair:
typedef struct {
cond_check_t checker;
exec_t executor;
} check_exec_t;
And with that, another struct to keep a bunch of these condition and executor pairs:
typedef struct {
size_t size;
size_t capacity;
check_exec_t *conditionals;
} cond_pack_t;
You then create support functions for adding checkers and executors and a function to processes one of these packaged checkers and executors.
cond_pack_t* cond_pack_create(size_t capacity) {
cond_pack_t* cp = malloc(sizeof(*cp));
if(cp) {
cp->conditionals = malloc(sizeof(*cp->conditionals) * capacity);
if(cp->conditionals) {
cp->size = 0;
cp->capacity = capacity;
} else {
free(cp);
cp = NULL;
}
}
return cp;
}
void cond_pack_destroy(cond_pack_t *cp) {
free(cp->conditionals);
free(cp);
}
bool cond_pack_add(cond_pack_t *cp, cond_check_t checker, exec_t executor) {
if(cp->size == cp->capacity) return false;
cp->conditionals[cp->size].checker = checker;
cp->conditionals[cp->size].executor = executor;
++cp->size;
return true;
}
void cond_pack_process(cond_pack_t *cp) {
for(size_t i = 0; i < cp->size; ++i) {
if(cp->conditionals[i].checker(NULL)) { /* execute checker */
cp->conditionals[i].executor(NULL); /* execute executor */
}
}
}
With that, a usage example could look like this
//---
bool some_check(void *foo) {
return true;
}
void some_executor(void *foo) {
printf("some_executor\n");
}
bool some_other_check(void *foo) {
return false;
}
void some_other_executor(void *foo) {
printf("some_other_executor\n");
}
int main() {
cond_pack_t *cp = cond_pack_create(10);
if(cp) {
cond_pack_add(cp, some_check, some_executor);
cond_pack_add(cp, some_other_check, some_other_executor);
cond_pack_process(cp); /* run all the checkers / executors */
cond_pack_destroy(cp);
}
}
Demo
I am trying to create a small fixed size list of string, int tuples. A fixed size array of structs seemed like the way to go, but when manipulating the array entries, I constantly run into memory errors. What I've tried so far:
public struct S {
public string a;
public int b;
public S (string a, int b) {
this.a = a;
this.b = b;
}
}
public class Test {
public S arr[5];
public static void main () {
var test = new Test ();
test.arr[0].a = "hi";
test.arr[0].b = 5;
/* alternatively: */
//test.arr[0] = S ("hi", 5);
}
}
I have looked into the compiled C code, but I am not really familiar with C.
I read everything I found about vala structs and arrays of structs, but the little bit that's out there didn't enlighten me either.
The fixed size array seems to get initialized with "empty" structs, do I need to initialize it beyond that, somehow?
What am I misunderstanding about arrays of structs here?
Is there an alternative way to implement a fixed size list of string, int tuples? Are arrays of structs not suited for that?
Any help is greatly appreciated! It seems like such a simple task, but I've been struggling with it for days now :/ ...
First, you can make the C code quite a bit simpler by specific "Compact" on the class and disabling the type on the struct:
[CCode(has_type_id = false)]
public struct S {
public string a;
public int b;
public S (string a, int b) {
this.a = a;
this.b = b;
}
}
[Compact]
public class Test {
public S arr[5];
public static void main () {
var test = new Test ();
test.arr[0].a = "hi";
test.arr[0].b = 5;
/* alternatively: */
//test.arr[0] = S ("hi", 5);
}
}
Not a full answer, but it seems like there is a problem in the compiler generated destruction code:
void test_free (Test* self) {
_vala_array_destroy (self->arr, 5, (GDestroyNotify) s_destroy);
g_slice_free (Test, self);
}
static void _vala_array_destroy (gpointer array, gint array_length, GDestroyNotify destroy_func) {
if ((array != NULL) && (destroy_func != NULL)) {
int i;
for (i = 0; i < array_length; i = i + 1) {
if (((gpointer*) array)[i] != NULL) {
destroy_func (((gpointer*) array)[i]);
}
}
}
}
Note how the array parameter (which is of type gpointer, but was casted from an S[], namely arr) is casted to a gpointer* before the destroy_func () is called on it.
That would be fine if arr were a dynamic array, but it isn't.
If I modify the compiler output by hand everything works fine:
static void _vala_array_destroy (S* array, gint array_length, GDestroyNotify destroy_func) {
if ((array != NULL) && (destroy_func != NULL)) {
int i;
for (i = 0; i < array_length; i = i + 1) {
if (&array[i] != NULL) {
destroy_func (&array[i]);
}
}
}
}
The destroy function (destroy_func aka s_destroy) is now called on a valid S* (the address of the struct inside the array).
So it seems to me that you have discovered a compiler bug.
PS: Using a dynamic array works just fine, I would either do that or use some higher level data type like a Gee.ArrayList instead of a static array.
In this code, how do I call an array globally for other methods to use?
Background info on my code, we are asked to scan a file that contains DNA strands then translating it to an RNA Strand.
I receive the error: " cannot find symbol - variable dna " when i call the dna array on the translation method (it can't find dna.length) for(int i=0; i < dna.length; i++){
public class FileScannerExample
{
public static void main(String[] args) throws IOException
{
//This is how to create a scanner to read a file
Scanner inFile = new Scanner(new File("dnaFile.txt"));
String dnaSequence = inFile.next();
int dnalength = dnaSequence.length();
String[] dna = new String[dnalength];
for(int i=0; i<=dna.length-2 ; i++)
{
dna[i]=dnaSequence.substring(i,i+1); //looking ahead and taking each character and placing it in the array
}
dna[dna.length-1]=dnaSequence.substring(dna.length-1); //reading the last spot in order to put it in the array
//Testing that the array is identical to the string
System.out.println(dnaSequence);
for(int i = 0 ; i<=dna.length-1; i++)
{
System.out.print(dna[i]);
}
}
public void translation()
{
for(int i=0; i < dna.length; i++){
//store temporary
if (dna[i] = "A"){
dna[i] = "U";
}
if(dna[i] = "T"){
dna[i] = "A";
}
if(dna[i] = "G"){
dna[i]= "C";
}
if(dna[i] = "C"){
dna[i] = "G";
}
}
}
}
you need to bring the symbol into scope before you can reference it. you can do this, either by pulling it up into a higher scope (as a field in the class), or by sending it into the local scope by passing it as a method parameter.
As a class member:
public class Test
{
private String myField;
void A() {
myField = "I can see you";
}
void B() {
myField = "I can see you too";
}
}
As a method parameter:
public class Test
{
void A() {
String myVar = "I can see you";
System.out.println(myVar);
B(myVar);
}
void B(String param) {
param += " too";
System.out.println(param);
}
}
Note that in order to see an instance member, you must be referencing it from a non-static context. You can get around this by declaring the field as static too, although you want to be careful with static state in a class, it generally makes the code more messy and harder to work with.
When i run the below program which displays subsets of a given array, where array size is <=19 , it works fine. But if array size >19 it throws Java Heap Space Exception. How to overcome this problem in order to get subsets where array size > 19?
import java.lang.*;
import java.util.*;
class def
{
static List<List<Integer>> subset(int ele,List<List<Integer>> w)
{
if(w.size()==0)
{
List<Integer> temp=new ArrayList<Integer>();
temp.add(ele);
w.add(temp);
}
else
{
int i,len=w.size();
for(i=0;i<len;i++)
{
List<Integer> temp=new ArrayList<Integer>();
for(Integer agh:w.get(i))
{
temp.add(agh);
}
temp.add(ele);
w.add(temp);
}
List<Integer> ghi=new ArrayList<Integer>();
ghi.add(ele);
w.add(ghi);
}
return w;
}
static void sub(int set[])
{
List<List<Integer>> ints = new ArrayList<List<Integer>>();
int len=set.length,i;
for(i=0;i<len;i++)
{
ints=subset(set[i],ints);
}
int count=0;
for(List<Integer> temp:ints)
{
System.out.println("SET---"+count++);
for(Integer agh:temp)
{
System.out.println(agh);
}
}
}
public static void main(String args[])
{
int a[]={3,4,9,14,15,19,28,37,47,50,54,56,59,61,70,73,78,81,92,95,97,99};
sub(a);
}
}
Here is the exception:
C:\Program Files (x86)\Java\jdk1.6.0_07\bin>javac def.java
C:\Program Files (x86)\Java\jdk1.6.0_07\bin>java def
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2760)
at java.util.Arrays.copyOf(Arrays.java:2734)
at java.util.ArrayList.ensureCapacity(ArrayList.java:167)
at java.util.ArrayList.add(ArrayList.java:351)
at def.subset(def.java:22)
at def.sub(def.java:39)
at def.main(def.java:55)
It seems that you are making too much instance of ArrayList. You can increase the heap size. but I think you can make a small modification in your code
else
{
int i,len=w.size();
List<Integer> temp=new ArrayList<Integer>(); ///reuse this arraylist
for(i=0;i<len;i++)
{
for(Integer agh:w.get(i))
{
temp.add(agh);
}
temp.add(ele);
w.add(temp);
temp.clear();
}
List<Integer> ghi=new ArrayList<Integer>();
ghi.add(ele);
w.add(ghi);
}
return w;
Though this may not solve your problem fully. But obviously it will help the garbage collector to take some rest. :D
The reason you are getting a heap error is because you are creating billions of lists.
Do not create sublists just display them.
public static void sub(int[] input){
sub(new int[0],input);
}
public static void sub(int[] current, int[] remaining){
System.out.println(Arrays.toString(current));
int[] newCurrent = Arrays.copyOf(current, current.length+1);
for(int i = 0;i < remaining.length;i++){
newCurrent[newCurrent.length-1] = remaining[i];
sub(newCurrent , Arrays.copyOfRange(remaining, i + 1, remaining.length));
}
}
otherwise you will need a smarter data structer than a list of lists.
To reduce memory consumption you can store sets as bit fields, for example set with elements 3, 9, 14 will be represented as 10110000000000000000 - so for each subset you will need only one int