CMSC104

• Home
• Syllabus
• Schedule
• Topics
• Classwork
• Homework
• Resources

Lecture 6: Variables Conversion and Function Introduction

[Up]

Reading Assigned:   3.1-3.4

Homework Due:  None

Homework Assigned:  Homework 02 -- assigned last class, Homework 03 -- assigned this class

Classwork Assigned:  Classwork 04

Topics Covered:

• #define directive
• Fatal errors -- Ran out of time last class
• Reminder - Variable types (and sizes)
  • int (4 bytes)
  • double (8 bytes) format
  • char (1 byte)
• Variable conversion
  • Automatic conversion
  • Explicit conversion
• Why do we need to use %lf for scanf but %f works for printf?
• Introduction to functions
  • Allows us to break up problems into smaller pieces
  • Effective programs break problems into the smallest reasonable pieces
  • Allows us to write code once and use it multiple times
• Function example:

  /*   File: func_example.c
       Name: D. Sheets
       Username: dsheets
       Date: 02/14/12
       Description: A simple function example
  */
  
  #include <stdio.h>
  
  /* A function to print a line of text */
  void my_function(void)
  {
     printf("This print is coming from my_function\n");
  }
  
  /* Main entry point for program */
  int main(void)
  {
     printf("Getting ready to call a function\n");
     my_function();
     printf("We called a function!\n");
     return(0);
  }
  

• Definitions of functions that don't take arguments are made up of of the following elements:
  1. return type
  2. function name
  3. (void)
  4. {
  5. Code of function
  6. }
• Functions that return values should end with "return(value)" where value is a constant or variable
• Functions that don't return values (ie. void) should end with "return()"