# Some Rules to keep in mind while writing code:

### Syntax 1: Statements should end with a semicolon ;
Code :

1. System.out.print(100)

Output :

Error: ';' expected
        System.out.print(100)
                             ^
1 error

Explanation :

Line 1 gives error because ; is missing.

### Syntax 2: Java is case sensitive which can differentiate between lower and upper case.
Code :

1. system.out.print(5000);

Output :

Error: package system does not exist
		system.out.print(5000);
		      ^
1 error

Explanation :

Line 1 gives error because S in System should be uppercase.

### Syntax 3: In order to print text we use double quotes.
Code1 :

1. System.out.print(Rahul);

Output :

Error: cannot find symbol

        System.out.print(Rahul);
                         ^

symbol:   variable Rahul

Explanation :

Code will give error because " " are missing.

Code2 :

1. System.out.print(“Rahul);

Output :

Error: unclosed string literal

        System.out.print("Rahul);
                               ^

Explanation :

This will give error because opening quote is present before Rahul but closing quote (") is missing after Rahul.

### Syntax 4: () , {}, “ ” → These should be in pairs
Code1 :

1. System.out.print("Rahul"};

Output :

Error: ')' expected

        System.out.print("Rahul"};
                                ^
1 error

Explanation :

This will give an error because we have to use same type of brackets on both sides.

Code2 :

1. System.out.print(Rahul;

Output :

Error: ')' expected

        System.out.print(Rahul;
                              ^
1 error

Explanation :

This will give an error because we use brackets in pairs.

### Syntax 5: Comments
Compiler will ignore the statements which are written as comments

1. **Single Line comment**

> // Single Line Comment

Code1 :

    1. // System.out.println(“Super”); 
    2. System.out.println(“Excited”);

Output:

    Excited

Explanation :

    Line 1 statement is a comment. So, Super is not getting printed.

2. **Multi Line comment**
>/*
This is a
multi - line
comment
*/

Code2 :

    1. System.out.println("Good Morning");
    2. /* System.out.println(“Super”); 
    3. System.out.println(“Excited”);
    4. */
    5. System.out.println("Hello");

Output:

    Good Morning
    Hello

Explanation :

    Line 2, 3 and 4 are a part of multi line comment. So, Super and Excited are not getting printed in the output.

### Syntax 6: print() vs println()

Code1 :

1. System.out.print(“Hello Guys!!”);
2. System.out.print(“My name is Rahul.”);

Output :

Hello Guys!!My name is Rahul.

Code2 :

1. System.out.println(“Hello Guys!!”);
2. System.out.print(“My name is Rahul.”);

Output :

Hello Guys!!
My name is Rahul.

Explanation :

> System.out.print → Prints the output and cursor remains in same line.
> System.out.println → Prints the output and cursor goes to the next line.