Initialization of variables

When declaring a regular local variable, its value is by default undetermined. But you may want a variable to store a concrete value at the same moment that it is declared. In order to do that, you can initialize the variable. There are two ways to do this in C++:

The first one, known as c-like initialization, is done by appending an equal sign followed by the value to which the variable will be initialized:

type identifier = initial_value ;

For example, if we want to declare an int variable called a initialized with a value of 0 at the moment in which it is declared, we could write:

 
int a = 0;


The other way to initialize variables, known as constructor initialization, is done by enclosing the initial value between parentheses (()):

type identifier (initial_value) ;

For example:

 
int a (0); 


Both ways of initializing variables are valid and equivalent in C++.

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// initialization of variables

#include
using namespace std;

int main ()
{
int a=5; // initial value = 5
int b(2); // initial value = 2
int result; // initial value undetermined

a = a + 3;
result = a - b;
cout << result;

return 0;
}