C program pi

Code written in C will need to be compiled before it can be run on a computer. When you compile your source file, a new compiled file gets created. For example, entering the command below will compile hello-world. Now we need to make the compiled file executable. To do that, we just need to change the file permissions. Enter this at the command prompt:. Now all we need to do to run the compiled, executable, C program is enter this at the command prompt:.

Hope this helps you get a basic idea on how to get started programming in C on the Raspberry Pi. If you have any questions, please leave a comment below, and if you know anyone who could enjoy this information, please share it!

You can also get our tutorials in your email by subscribing! For a beginner, C is the worst possible language to learn. That means I can manage to get a higher accuracy for PI than defined by C? That means newly defined accurate value is useless?? Show 1 more comment.

Maximilian Maximilian 21 1 1 silver badge 5 5 bronze badges. Douglas G. Allen Douglas G. Allen 2, 19 19 silver badges 19 19 bronze badges. Francis Cugler Francis Cugler 7, 2 2 gold badges 25 25 silver badges 47 47 bronze badges. RyanHaining That was a pure typo on my part thank you for pointing that out.

I made the appropriate corrections. It's still not valid C — Ryan Haining. It's been too many years since I worked in C. It's not clear to me what characteristics you do hope to have in an alternative that does not rely on a macro, but that's one of the main things you're up against.

I've updated the answer to accommodate for this Show 2 more comments. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.

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Featured on Meta. New post summary designs on greatest hits now, everywhere else eventually. Linked 0. That is the beginning of functions, loops, if statements etc. Quiet frankly everything that looks like this is valid syntax:. Newer versions of gcc allow you to declare variables everywhere, but try to avoid that. You probably want your program to be compatible with older versions of gcc and other compilers. Recall that argc is the number of arguments to the program.

If these are less than 2 we have a problem. Then we exit the program with the value 1. Why 1? I'll explain this at the end of this example, bare with me for a while. PRINT simply refers to printing, that is writing something to the shell.

Format means that want to format the output in some sense. Check your manpages for fprintf that is man fprintf for a lot more details. This for-loop can be interpreted as follows. First set i to 0, then s to atoi argv[0]. Observe that we do both these things before the first ;. This part is just done once, that is when we enter the loop.

What is this atoi? The argument "" in the example above, i. Therefor we have to convert this string to a number. This loop will loop as long as i is less than s. This test is done at the beginning of the loop. In every iteration of the loop i will be incremented by one. This is done at the end of the loop. This loop is as said repeated say times, after that we multiply the result by 4, according to the formula.

Now lets print the result. Here again we use formated printing.