Let’s look at structure of a program
#include<stdio.h> /* Header File */
main () /* starting function */
{ /* start of program */
--------
Statements;
--------
} /* end of program */
-
There should be a main ( ) function somewhere in the program to determine where to start the executions.
-
Usually all C statements are entered in small case letters.
-
The group of statements in main ( ) are executed sequentially.
-
The left brace indicates the program opening.
-
The right brace indicates the program closing.
-
In C language Comments are enclosed with /* -- */ means these statements won’t execute when the program is complied.
A C program consists of one or more functions. Each function performs a specific task. A function is a group or sequence of C statements that are executed together.
Every C program starts with a function called main(). This is the place where program execution begins. Hence, there should be main() function in every C program. The functions are building blocks of C program. Each function has a name and a list of parameters.
The following are some rules to write C programs
-
All C statements must end with semicolon.
-
C is case – sensitive. That is, upper case and lower case characters are different. Generally the statements are typed in lower case.
-
A C statement can be written in one line or it can split into multiple lines.
-
Braces must always match upon pairs, i.e., every opening brace ‘{‘ must have a matching closing brace ‘}’.
-
A comment can be split into more than one line.
REVIEW OF TERMS
The terms that follow will be used frequently throughout the C. you should be completely familiar with them.
-
Source Code: The text of a program that a user can read commonly thought of as the program. The source code is input into the C compiler.
-
Object Code: Translation of the source code of a program into machine code, which the computer can read and execute directly. Object code is input to the linker.
-
Linker: A program that links separately compiled modules into one program. It also combines the functions in the Standard C library with the code that you wrote. The output of the linker is an executable program.
-
Library: The file containing the standard functions that your program can use. These functions include all I/O operations as well as other useful routines.
-
Compile Time: The time during which your program is being compiled.
-
Run Time: The time during which your program is executing.
