Write a Hello World application with C

This section outlines the steps to write a C program in Geany.

1. Launch Geany. From the desktop, select Applications > Development > Geany.

2. Select Project > New. Name the project hello_world_c.

   The fields represent the following:

   • Name — The name of the project.
   • Filename — The filepath of the project, where the project settings are stored. This path generally ends in .geany
   • Base path — The base path of all files making up the project.
   
   
   

3. Click OK when prompted to create the directory.

4. Write a Hello World sample application. This example uses:

   #include <stdlib.h>
   #include <stdio.h>
   
   int main (int argc, char **argv)
   {
       printf("Hello World!);
   
       char *buf = NULL;
   
       printf("%d", *buf);
   
       exit(0);
   }

5. Select File > Save As, and save it as hello_world.c.

6. Select Build > Compile to compile the source.

7. Select Build > Build to create an executable for the code.

8. Select Build > Execute to execute the code in a terminal window:

   
   
   

9. Try the linting function by adding the following code after your print statement:

   char *buf = NULL;
   
   printf("%d", *buf);

10. Select Build > Lint. You should see a warning for dereferencing a NULL pointer:

    
    
    

11. Next, try debugging the Hello World sample. Update the compile commands to include the -g flag by selecting Project > Properties.

12. Select the Build tab and update the Compile and Build commands to include -g:

    
    
    

13. Select Debug > Setup Program.

14. Enter the full path to the hello_world executable, then click OK:

    
    
    

15. Set a breakpoint on the printf() statement. Click the line in the IDE, then select Debug > Toggle Breakpoint. A blue dot appears next to the respective line number:

    
    
    

16. Select Debug > Run/Continue to run the debugger.

17. Once the breakpoint has been hit, select Debug > Run/Continue or Debug > Step Over.