Why put double & in c++

Question

example &&

Answer 1

If a user enters say the number of apples available for sale, and it must be both positive AND is actually an even number, u can use && as a tool to make sure that these two conditions are fulfilled.

Look at the code below. If the user enters 1 or 3, the if statement will not run the print (cout ...) line, but if 2, 4, 10, etc, was entered, you will see "wow! 2 apples." Or "wow! 4 apples" etc.

This is bcos the number entered is both positive and even.

void main()
{
int num=0;

cout << "enter the number of apples avalable: "<< endl;
cin >> num;

//here we test if input is valid
If (num>0)&&(num%2==0)
cout <<"wow! " << num << "apples!"<< endl;

}

Answer 2

Double & or (&&) is c++ syntax for the logical operator "AND". Example:

If (1<2)&&(2<3)
Cout <<"yes";

This implies: If both sides of the operator && tests as true, then and only then will the output be "yes".

And In this case ofcourse the output is "yes"

Answer 3

Just so you know: You can't confuse & with && operator. Single & is used as bitwise operator, it works same as "AND" logic gate but only on integer values.

Answer 4

can you give more example i dont really understand

Answer 5

@ahmad
int a = 5;
int b = 3;

int c = a & b; // c equals 1

Answer 6

if(i>0&&i<5)

it means that "i" must be higher than 0 and lower than 5 at the same time. "if" will start only when these two conditions are true. (opposite of "||")

if(i>0||i<5)

in this case we are checking if i>0 or i<5, so if one of these conditions is true "if" will start. In this case "if" will be true for every i number.
------------------------------------------------------------------------------------------------------
int i=5;

if(i>0&&i<5) //It will not work becouse only one "i>0" condition is true. "i<5" is false
{
cout<<"You can't see me";
}

if(i>0&&i<6) //Now both conditions are true
{
cout<<"It works!";
}

Answer 7

& is used to receive the memory address of a variable (which would be called a pointer). An example:

int *hi = &52;

&& is used as the "and" operator. An example:

if ((5+5==0) && (2+2=4)) {
}

5+5 obviously doesn't equal 0. 2+2 does equal 4. Since it's using &&, it's false. If it was using || which is the OR operator, it'd be true.

So, essentially, all statements included with a && operator must be true, otherwise it'll return false for the entire statement.