First C Program

Write down the following program in a text editor.
Output:
Welcome to TutorialRide

In the above program

#include <stdio.h>

• It is the preprocessor command. It is the first statement of the program.
• It starts with a hash (#) symbol.
• The #include will tell the compiler to include the standard input/output library file (stdio.h).
• The above file also has some built-in functions. By simply adding this file we can directly use the functions.

void main()
void will not return anything to the main() function. If a parenthesis is not placed after the 'main', there will be a compilation error.

{ }

• The curly brackets are used for grouping together all the statements.
• These statements together form the function body.
• They can be called as a set of instructions that are used for performing a given set of tasks.

printf(“\n Welcome to TutorialRide”);

• The printf function is already defined in the stdio.h file.
• It is used for printing the text on the screen.
• Whatever message needs to be printed should be enclosed in double quotes inside brackets.
• '\n' is an escape character which represents a newline character.

Other escape characters are as follows:

Escape Sequence	Purpose
\a	Audible signal
\b	It creates a backspace
\t	Tab
\n	Newline
\f	New page\Clear screen
\r	Carriage return
\?	Question mark
\\	Back slash
\'	Single quote
\”	Double quote
\0	Octal constant
\x	Hexadecimal constant

Compilation and Execution of a C program

Every programming language has its own compiler.

Process of compilation and execution:

• The process starts with the source file and ends with the executable file.
• A source file is created which consists of statements written in C.
• The source file is then processed by the compiler.
• Compiler will translate the source code into object code. Object code contains the machine instructions for the CPU and calls the operating system API.
• The object file is not an executable file.
• The object file is then processed with a linker.
• There can be different compilers for the program but has a same linker for the object files.
• The output of this linker will be an executable file.

Following diagram explains us modular programming where the source code is divided into two or more source files . The source files are compiled separately which in turn produces multiple object files. These object files are combined by the linker for producing an executable file.