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Difference between c and java on simple array functions? [closed]

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Besides some obvious difference like difference [] placement, are there any fundamental difference between array in java and in c?
I wrote small program that calculates sum to compare them.
//java
public static int arraySum(int[] a) {
int sum = 0;
for (int i = 0; i < a.length ; i++) {
sum = sum + a[i];
}
return sum;
}
public static void main(String[] args) {
int[] tryArray = {1,2,3,4,5};
System.out.println(arraySum(tryArray));
}
//c
int sum_array(int a[], int len) {
int sum = 0;
for (int i = 0; i < len; ++i) {
sum += a[i];
}
return sum;
}
int main(void) {
int my_array[5] = {1,2,3,4,5};
trace_int(sum_array(my_array, 5)); // any ways to remove the 5(length) from the parameter?
}
Also, if I use char arrays in c, it looks like string in java? char posi_string[3] = "str"
Can I use this method to manipulate string in c?

Any ways to remove the length from the parameter?
No. When you pass an array to a function in C, it is no longer assumed as an array but a pointer. Since it's a pointer, you can no longer evaluate its size with sizeof(arr) / sizeof(arr[0]) – thus, you just need to pass another parameter, for example, size to tell the array size to the function.
If I use char arrays in C, does it looks like a string in Java?
No. Java has a String class that is rich in built-in code. Unlikely in C, char is a primitive data type, and it has no functions, you need to create one manually.

How to initialize this array so that it works in the while loop? [closed]

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I am trying to initialize an array above a while loop and then use the array set the values of the array in the while loop. But netbeans keeps giving me an error message.
public static void main(String[] args) {
int a=999;
int b=999;
int c=0;
int[] array = new int[5];
int[] array2= new int[6];
while(c<=998001){
c=a*b;
if(c<100000){
array[]={c%100000,c%10000,c%1000,c%100,c%10}
//netbeans keeps telling me that this array is "not a statement"
";" expected. Why does it tell me this?//
}
if(array[0]==array[5] & array[1]==array[3]){
int d=c;
}
}
}

Because your syntax isn't valid Java. It seems you want to create a new 5 element array with your statement. You could do so like
array = new int[] { c % 100000, c % 10000, c % 1000, c % 100, c % 10 };
But since you always have five elements, it would probably be more efficient to use a loop and re-use the same array. Like,
if (c < 100000) {
int fac = 100000;
for (int i = 0; i < array.length; i++) {
array[i] = c % fac;
fac /= 10;
}
}

List the factors of an integer [closed]

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public int[] factors(int n) {
int count[] = new int[n];
for (int i = 1; i <= count.length; i++) {
count[i] = (count.length % i);
}
return count;
}
}
Anyone have an idea how to list all the factors?

set int i = 0; as array starts from 0
Factor can only be considered if value % i==0 so add if condition
You need one more variable to increment array Index as you can't use i for that.So add one more variable to increment array index to add factor.
Think more on your code, debug especially if possible,check out the values ,add print statements if needed to see what's going on and that's it you will definitely win the task.
Other than that if you can use SOF you can use Google as well :)

You should use a List instead of array. Since you can't initialize the array without knowing the size.
Then you can try something like following
public List<Integer> factors(int n) {
List<Integer> list = new ArrayList<>(); // initialize the list
for (int i = 1; i <= n; i++) {
if (n % i == 0) { // decide the factor.
list.add(i); // now i is a factor, needs to add to list
}
}
return list; // return list contains factors.
}

Pascal's Triangle - algorithm works in C++ but got 'Time Limit Exceeded' in java [closed]

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A leetcode problem: Given numRows, generate the first numRows of Pascal's triangle.
The C++ version of this algorithm got accepted by Leetcode. Could anyone tell me why this Java version cannot get accepted?
public class Solution {
public List<List<Integer>> generate(int numRows) {
List<List<Integer>> result = new ArrayList<List<Integer>>();
if (numRows == 0) return result;
List<Integer> raw = new ArrayList<Integer>();
raw.add(1);
result.add(raw);
if (numRows == 1) return result;
List<Integer> row = raw;
List<Integer> row2 = raw;
for (int i = 2; i <= numRows; i++) {
for (int j = 0; j < row.size()-1; j++)
row2.add(row.get(j) + row.get(j+1));
row2.add(1);
result.add(row2);
row = row2;
row2 = raw;
}
return result;
}
}

Could anyone tell me why this Java version cannot get accepted?
Because your code runs forever.
You have exactly one List<Integer> and it keeps growing:
for (int j = 0; j < row.size()-1; j++)
row2.add(row.get(j) + row.get(j+1));
In each iteration you move one element forward and add one element, to the same list, essentially eternally chasing the end that keeps getting away.
(I had a friend at uni who initially also didn't understand how references work in Java and made a similar mistake with Lists. He got like a bazillion buttons in a Swing GUI.)

Populate int array with for loop in Java [closed]

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I have an array named numbers that I want to populate with a for loop:
int[] numbers;
for ( int i = 0; i <=10; i++)
{
// want to populate the array with a sequence of 0-10
}
How can I populate the 11 values generated from the above for loop into my array?

If you are using Java 7 or lower, do this:
int[] numbers = new int[11];
for ( int i = 0; i <=10; i++)
{
numbers[i] = i;
}
For Java 8, there is a more concise way to do this:
int[] numbers = IntStream.rangeClosed(0, 10).toArray()

First you need to define what numbers is, you have only declared it.
int[] numbers = new int[11];
Then insert the values you want.
for ( int i = 0; i <=10; i++)
{
numbers[i] = i;
}