data structures using this command is used to compile your program if there are any mistakes in the programthen the compiler will tell you what mistake(syou have made and on which line the error has occurred in case of errorsyou need to re-open your file and correct the mistakes howeverif everything is rightthen no error(swill be reported and the compiler will create an exe file for your program this exe file can be directly run by typing "first exefor windows and /firstfor unix/linux operating system when you run the exe filethe output of the program will be displayed on screen that iswelcome to the world of note the printf and return statements have been indented or moved away from the left side this is done to make the code more readable using comments comments are way of explaining what program does supports two types of comments /is used to comment single statement /is used to comment multiple statements /is ended with *and all statements that lie between these characters are commented note that comment statements are not executed by the compiler ratherthey are ignored by the compiler as they are simply added in programs to make the code understandable by programmers as well as other users it is good habit to always put comment at the top of program that tells you what the program does this helps in defining the usage of the program the moment you open it standard header files till now we have used printf(functionwhich is defined in the stdio header file even in other programs that we will be writingwe will use many functions that are not written by us for exampleto use the strcmp(function that compares two stringswe will pass string arguments and retrieve the result we do not know the details of how these functions work such functions that are provided by all compilers are included in standard header files examples of these standard header files includestring for string handling functions stdlib for some miscellaneous functions stdio for standardized input and output functions math for mathematical functions alloc for dynamic memory allocation conio for clearing the screen all the header files are referenced at the start of the source code file that uses one or more functions from these files input and output functions the most fundamental operation in program is to accept input values from standard input device and output the data produced by the program to standard output device as shown in section we can assign values to variables using the assignment operator '=for exampleint what if we want to assign value to variable that is inputted from the user at run-timethis is done by using the scanf function that reads data from the keyboard similarlyfor outputting results of