How Do You Create a Function in the C Programming Language?

Problem scenario
You are familiar with functions in programming languages (e.g., Python or SQL).  You like how you can create a modular program with a function.  Functions can allow you to reuse code and do data processing in a way that is readable.  Logic can be created rapidly when you know how to use a function.  How do you write a function in the C?


Install the C compiler.  If you need directions, see this posting.

Use this example.  The function here is called "printer". 

1.  Create a file called  

2.  Put the following lines in it (starting with "/* function example */" and ending with the last "}").

/* function example */
#include <stdio.h>
#include <string.h>

int printer(int z) {
   printf ("found %s\n","a test");
   z = z + 1;
   return z;
int main ()
  int y;
  y = printer(3);
  printf ("y is a %d\n",y);
  return 0;

3.  Compile the code with gcc

4.  Run it like this: ./a.out
You should see that y was assigned via the "printer" function.  Remember that "printer" is not a reserved word.  It is a function that returns an integer based on the way it was defined above.

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