1. Structure of C Programs
Yung-Hsiang Lu
Purdue University

2. If you understand the previous example (first
If you understand the previous example (first.c), you can skip this lecture.

3. /. first. c. Created on: Jun 3, 2016. Author: yunglu
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }

4. Comments between /* and */
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
Comments
between /* and */

5. /. first. c. Created on: Jun 3, 2016. Author: yunglu
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
include header files

6. /. first. c. Created on: Jun 3, 2016. Author: yunglu
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }

7. "main" is the starting point of a C program
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
"main" is the starting
point of a C program

8. "main" returns an integer, EXIT_SUCCESS or EXIT_FAILURE
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
"main" returns an
integer, EXIT_SUCCESS
or EXIT_FAILURE

9. "main" takes two arguments, an integer and an char * *
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
"main" takes two
arguments, an integer
and an char * *

10. Their names are always "argc" and "argv". Do not change the names.
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
Their names are always
"argc" and "argv".
Do not change the names.

11. argc: number of arguments c = count
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
argc: number of arguments
c = count

12. argv: values of arguments v = value
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
argv: values of arguments
v = value

13. A function's body starts with { and ends with }
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
A function's body starts
with { and ends with }

14. print a message in a given format f = formatting
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
print a message in a given
format
f = formatting

15. /. first. c. Created on: Jun 3, 2016. Author: yunglu
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
\n means a new line

16. This simple program always succeeds.
/* * first.c * * Created on: Jun 3, 2016 * Author: yunglu */ #include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { printf("Hello C\n"); return EXIT_SUCCESS; }
This simple program
always succeeds.