How to fill array in C++?

Following zohaib's answer: If your array is of fixed length: You can use the array's 'fill' member function like this: a.fill(b); If your array can change it's size you can use the std's fill function like this: std::fill(a.begin(), a.end(), b);

I have an array "a"

int a = [];

What you have is a syntax error.

As I remember in python its simply uses apppend

A major difference between a C++ array and python list is that the size of C++ array cannot change, and thus nothing can be appended into it.

How to fill array in C++?

There is indeed a standard algorithm for this purpose:

int a[4];
int b = 10;
std::fill_n(a, std::size(a), b);

Here one solution how to use your array header.

int b = 10;
std::array<int, 3> a;
std::fill(begin(a), end(a), b);

Decide the size for a, as it is an array not a list. For example:

int a[10];

Then use index values to fill in the array like:

a[0] = 1;
a[1] = 4;

etc.

If you want a dynamic array use std::vector instead

Here is how its done with vectors:

std::vector<int> myvector;
int myint = 3;

myvector.push_back (myint);