In this tutorial, you’ll learn about basic Structure of a C program, Comments, Compilation and execution and Receiving input from the user.
All c programs have to follow a basic structure. A c program starts with the main function and executes instructions presents inside it. Each instruction terminated with a semicolon(;)
There are some basic rules which are applicable to all the c programs:
- Every program’s execution starts from the main function.
- All the statements are terminated with a semi-colon.
- Instructions are case-sensitive.
- Instructions are executed in the same order in which they are written.
Comments are used to clarify something about the program in plain language. It is a way for us to add notes to our program. There are two types of comments in C:
- Single line comment: //This is a comment.
- Multi-line comment : /*This is multi-line comment*/
Comments in a C program are not executed and ignored.
Compilation and execution
A compiler is a computer program that converts a c program into machine language so that it can be easily understood by the computer.
A program is written in plain text. This plain text is a combination of instructions in a particular sequence. The compiler performs some basic checks and finally converts the program into an executable.
C language has a lot of valuable library functions which is used to carry out a certain task; for instance, printf function is used to print values on the screen.
printf(“This is %d”,i); // %d for integers // %f for real values // %c for characters
Receiving input from the user
In order to take input from the user and assign it to a variable, we use scanf function.
The syntax for using scanf:
scanf(“%d”,&i); // [This & is important]
& is the “address of” operator, and it means that the supplied value should be copied to the address which is indicated by variable i.
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