If I want to append a number to an array initialized to int, how can I do that?
int arr[10] = {0, 5, 3, 64};
arr[] += 5; //Is this it?, it's not working for me...
I want {0,5, 3, 64, 5} in the end.
I'm used to Python, and in Python there is a function called list.append that appends an element to the list automatically for you. Does such function exist in C?
There are only two ways to put a value into an array, and one is just syntactic sugar for the other:
a[i] = v;
*(a+i) = v;
Thus, to put something as the 4th element, you don't have any choice but arr[4] = 5
. However, it should fail in your code, because the array is only allocated for 4 elements.
If you have a code like
int arr[10] = {0, 5, 3, 64};
, and you want to append or add a value to next index, you can simply add it by typing a[5] = 5
.
The main advantage of doing it like this is you can add or append a value to an any index not required to be continued one, like if I want to append the value 8
to index 9, I can do it by the above concept prior to filling up before indices.
But in python by using list.append()
you can do it by continued indices.
You can have a counter (freePosition), which will track the next free place in an array of size n.
Short answer is: You don't have any choice other than:
arr[4] = 5;
For some people which might still see this question, there is another way on how to append another array element(s) in C. You can refer to this blog which shows a C code on how to append another element in your array
.
But you can also use memcpy()
function, to append element(s) of another array. You can use memcpy()
like this:
#include <stdio.h>
#include <string.h>
int main(void)
{
int first_array[10] = {45, 2, 48, 3, 6};
int scnd_array[] = {8, 14, 69, 23, 5};
// 5 is the number of the elements which are going to be appended
memcpy(a + 5, b, 5 * sizeof(int));
// loop through and print all the array
for (i = 0; i < 10; i++) {
printf("%d\n", a[i]);
}
}
Source: Stackoverflow.com