Conditional operator problem ?

[dragcro]

Can u help me with the code below, idea is to sum the numbers in range of brKarika
lets say br Karika =4 and numbers are:
3 11 4 7
so
suma[1]=3+13
suma[2]=3+13+4
suma[3]=3+11+4+7

int brKarika;
cout << "Unesi broj karika u pronadenom lancu" << endl;
cin >> brKarika;
vector<int> suma;
suma.resize(brKarika);

	for (int i=0; i<brKarika; i++)
	{
		cin >> karika;

		suma[i] = (i == 0) ? karika : suma[i-1] + karika; // kumulativno zbrajamo cvrstoce
	}

suma[i] = (i == 0) -> this part is confusing me, can somebody explain it to me
for karika values inputed we check if value suma of indx i is equal to ??, cuz i==0 wil return true in first step, but suma[0] can be any number, help needed please guys.

Tnx in advance

[MikeyBoy]

suma[i] = (i == 0) -> this part is confusing me, can somebody explain it to me

It's the ternary operator. Google "C++ ternary operator" for information.

[The illusionist mirage]

It is the conditional operator, the ternary operator in C++. It has the general form of:

(test-expression)?(expression-2):(expression-3)

If test-expression is true, then expression-2 is executed and if it is false, expression-3 is executed.

Example:

.
.

int x = 3;
(x > 3)?(cout << "Hello";):(cout << "Goodbye";);

The output the of the following would be:

Goodbye

Hope that helped.

[dragcro]

ok then in my case test expression is suma[i]=(i==0)
i still dont understand expression?? that is why i asked in first place, i get how conditional operator works, but dont get how this expression does?

[Chervil]

in my case test expression is suma[i]=(i==0)

Not exactly. The expression being tested is just (i==0)

This line:

    suma[i] = (i == 0) ? karika : suma[i-1] + karika;

can be re-written like this:

    if (i == 0)
        suma[i] = karika;
    else
        suma[i] = suma[i-1] + karika;

Please see "Conditional operator ( ? )" here:
http://www.cplusplus.com/doc/tutorial/operators/

[dragcro]

that is what i wanted to know, i've checked the link and my mind started to understand :)
after that i returned here and saw your post with the same link :)

cuz actually i will stick to writing if conditions, sometimes conditional operotor and it sintax confuses me

tnx a lot man .
have a nice day