How To Write First Program in C
Yes - it's the ubiquitous "Hello World" program. All your first program is going to do is print the message "Hello World" on the screen.
The first line is the standard start for all C programs - main(). After this comes the program's only instruction enclosed in curly brackets {}. The curly brackets mark the start and end of the list of instructions that make up the program - in this case just one instruction.
Notice the semicolon marking the end of the instruction. You might as well get into the habit of ending every C instruction with a semicolon - it will save you a lot of trouble! Also notice that the semicolon marks the end of an instruction - it isn't a separator as is the custom in other languages.
If you're puzzled about why the curly brackets are on separate lines I'd better tell you that it's just a layout convention to help you spot matching brackets. C is very unfussy about the way you lay it out. For example, you could enter the Hello World program as:
main(){printf("Hello World\n");}
but this is unusual.
The printf function does what its name suggest it does: it prints, on the screen, whatever you tell it to. The"\n" is a special symbols that forces a new line on the screen.
OK, that's enough explanation of our first program! Type it in and save it as Hello.c. Then use the compiler to compile it, then the linker to link it and finally run it. The output is as follows:
Hello World