Selection statements | Difference between if else and else if

Selection statements

if statement if~else statement

• ikki yoki undan ko'p execution pathlarni tanlaydi

if (a>=0)
cout << "positive";
if (a<0)
cout << "negative";

If statement

• if expression is true, execute statement1
  • Syntax

if(expression)
{(body) 
statement1
} 

• Example

if (a>=0)
cout << "positive";

• don't use semi-colon (;) after if(expression)
  • Agar semi-colon ishlatilsa, if statement mustaqil bo'lib qoladi.
• Agar if statementda faqat bitta statement bo'lsa {} qo'yilmaydi.

    int a,b,c;

  cin >> a >> b >> c;

  int max = a > b ? a : b;

    if (max > c)
      cout << max << endl;

• Agar if statement condition bajarilmasa output da hech narsa chiqmaydi.

• If statement faqat o'zidan keyingi birinchi turgan cout ga ta'sir qiladi.

• Use == (Realtion operator), don't use = (Assignment)
  

    if (team == '10')
    cout << "Lions" << endl;
not
    if (team = '10')
        // result team is 10

If-else statement

• If expression is true, execute statement1. If false, execute statement2
• Syntax

if(expression)
{(body) 
statement1
} 
else
{(body) 
statement2
}  

• Example

    if (son%2 == 0)
    cout << "even" << endl;
    else 
    cout << "odd" << endl;

• if statement contains another if statement (including if-else statement)

if (a>=0)
   if (x%2 ==0)
   cout << "positive even number" << endl;
   else 
   cout << "positive odd number" << endl;

else-if statement

• Example

    if (a>='A' && a<='Z')
    cout << "Upper-case" << endl;
        else if (a>='a' && a<= 'z')
        cout << "Lower-case" << endl;
            else if (a>='0' && a<='9')
            cout << "Number" << endl;
                else 
                cout << "Others" << endl;