Skip to main content
You have seen the basic structure of a C program, so it will be easy to understand other basic building blocks of the C programming language.

Tokens in C

A C program consists of various tokens and a token is either a keyword, an identifier, a constant, a string literal, or a symbol. For example, the following C statement consists of five tokens −
printf("Hello, World! \n");
The individual tokens are −
printf
(
"Hello, World! \n"
)
;

Semicolons

In a C program, the semicolon is a statement terminator. That is, each individual statement must be ended with a semicolon. It indicates the end of one logical entity.
Given below are two different statements −
printf("Hello, World! \n");
return 0;

Comments

Comments are like helping text in your C program and they are ignored by the compiler. They start with /* and terminate with the characters */ as shown below −
/* my first program in C */
You cannot have comments within comments and they do not occur within a string or character literals.

Identifiers

A C identifier is a name used to identify a variable, function, or any other user-defined item. An identifier starts with a letter A to Z, a to z, or an underscore '_' followed by zero or more letters, underscores, and digits (0 to 9).
C does not allow punctuation characters such as @, $, and % within identifiers. C is a case-sensitive programming language. Thus, Manpower and manpower are two different identifiers in C. Here are some examples of acceptable identifiers −
mohd       zara    abc   move_name  a_123
myname50   _temp   j     a23b9      retVal

Keywords

The following list shows the reserved words in C. These reserved words may not be used as constants or variables or any other identifier names.
auto else long switch
break enum register typedef
case extern return union
char float short unsigned
const for signed void
continue goto sizeof volatile
default if static while
do int struct _Packed
double


Whitespace in C

A line containing only whitespace, possibly with a comment, is known as a blank line, and a C compiler totally ignores it.
Whitespace is the term used in C to describe blanks, tabs, newline characters and comments. Whitespace separates one part of a statement from another and enables the compiler to identify where one element in a statement, such as int, ends and the next element begins. Therefore, in the following statement −
int age;
there must be at least one whitespace character (usually a space) between int and age for the compiler to be able to distinguish them. On the other hand, in the following statement −
fruit = apples + oranges;   // get the total fruit
no whitespace characters are necessary between fruit and =, or between = and apples, although you are free to include some if you wish to increase readability.

Comments

Post a Comment

Popular posts from this blog

In this chapter, we will see how to enable remote desktop application. It is important because this enables us to work remotely on the server. To do this, we have the following two options. For the first option, we have to follow the steps given below. Step 1  − Go to Start → right click “This PC” → Properties. Step 2  − On Left side click “Remote Setting”. Step 3  − Check radio button “Allow Remote connection to this computer” and Check box “Allow connection only from computers running Remote Desktop with Network Level Authentication (recommended)” → click “Select Users”. Step 4  − Click Add. Step 5  − Type user that you want to allow access. In my case, it is administrator → click OK. For the  second option , we need to follow the steps given below. Step 1  − Click on “Server Manage” → Local Server → click on “Enable” or Disable, if it is Disabled.
Post a Comment
Read more
The table creation command requires: Name of the table Names of fields Definitions for each field Syntax: Here is generic SQL syntax to create a MySQL table: CREATE TABLE table_name ( column_name column_type ); Now, we will create following table in  TUTORIALS  database. tutorials_tbl ( tutorial_id INT NOT NULL AUTO_INCREMENT , tutorial_title VARCHAR ( 100 ) NOT NULL , tutorial_author VARCHAR ( 40 ) NOT NULL , submission_date DATE , PRIMARY KEY ( tutorial_id ) ); Here few items need explanation: Field Attribute  NOT NULL  is being used because we do not want this field to be NULL. So if user will try to create a record with NULL value, then MySQL will raise an error. Field Attribute  AUTO_INCREMENT  tells MySQL to go ahead and add the next available number to the id field. Keyword  PRIMARY KEY  is used to define a column as primary key. You can use multiple columns separated by comma to define...
Post a Comment
Read more
In this chapter, we will see how to configure WSUS and tune it. The following steps should be followed for configuring it. Step 1  − When you open it for the first time, you should do it by going to “Server Manager” → Tools → Windows Server Update Services, then a Configuration wizard will be opened and then click → Next. Step 2  − Click “Start Connecting” → Wait until the green bar is full and then → Next. Step 3  − Check the box for which the updates want to be taken, I did for English and then → Next. Step 4  − Check the box for all the products which you want to update. It is just for Microsoft products and it is recommended to include all the products related to Microsoft and then → Next. Step 5  − Choose the classification updated to be downloaded, if you have a very good internet speed, then check all the boxes, otherwise just check “Critical Updates”. Step 6  − Now we should schedule the updates which I will recommend to do it a...
Post a Comment
Read more