define prototype code example

Example 1: function prototype

// function prototype
void add(int, int);

int main() {
    // calling the function before declaration.
    add(5, 3);
    return 0;
}

// function definition
void add(int a, int b) {
    cout << (a + b);
}

Example 2: prototype

String.prototype.countCharacter = function(char) {
    return [...this].filter(c => c === char).length;
}