can someone explain if statements in c++

Am I suppose to use curly braces in if statements

In my textbook it shows if statements without curly braces

like this

Code:

---

if(x=0)
cout<< x << "is 0" <<endl;

---

or is it suppose to be like this

Code:

---

if(x=0){
cout<< x << "is 0" <<endl;
}

---

or is there a difference between both because my professor gave me a sample code and he had curly braces in there

The examples, as you have shown them, are equivalent.

The difference shows up if you have more than two statements.

Code:

---

if (x == 0)
    step_1();
    step_2();

---

will always execute step_2() regardless of the value of x (indentation of the code doesn't change that) whereas

Code:

---

if (x == 0)
{
    step_1();
    step_2();
}

---

will not.

Also, be careful of

Code:

---

if (x = 0)
    cout<< x << "is 0" <<endl;

---

as it does NOT test if x is zero. It assigns x to the value zero, and then does not produce any output. The equality test is == (two equal signs, not one).

so let me get this clear

Code:

---

if (x == 0)
  cout << "Run this program"<<endl;
    cout <<"Run this too"<<endl;

---

Quote:

---

will always execute step_2() regardless of the value of x (indentation of the code doesn't change that) whereas

---

so it will display the statement "Run this too" if x is 1 and not 0
and both if x is 0. So basically step 2 in this one has nothing to do with the if statement before it?

Code:

---

if (x == 0)
{
    cout << "Run this program"<<endl;
    cout <<"Run this too"<<endl;
}

---

and this code will display both statements only if x = 0.

Quote:

---

Originally Posted by c++noob145

and both if x is 0. So basically step 2 in this one has nothing to do with the if statement before it?

Code:

---

if (x == 0)
{
    cout << "Run this program"<<endl;
    cout <<"Run this too"<<endl;
}

---

and this code will display both statements only if x = 0.

---

exactly right. the compiler considers the first statement after the if to be the one controlled by it. a block of statements wrapped in curly brackets will be seen by the compiler as one statement, with respect to the if statement.

The curly braces give the ' scope ' of the IF statement - the number of instructions it encapsulates

Quote:

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Originally Posted by rogster001

The curly braces give the ' scope ' of the IF statement - the number of instructions it encapsulates

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No it doesn't. The scope of an if statement is something else entirely.

The curly braces are used to compose a single statement from multiple statements.