1. In your notebook… Purpose: What types of data can we store in C
In your notebook… Purpose: What types of data can we store in C? Warmup, Copy these two lines to your notes and then answer in a sentence to tell what each line does. This is a shortcut way to combine those two lines into one line:

2. what happens? works okay?
Download twoChars.c from our web page.
Compile and make it work.
Copy this table to your notebook.
Try each pair above in lines 9 & 10 of your program. Write the results into your notebook. X
what happens? works okay? Y 68
‘D’
101
(101+1)
‘#’
“#”
“boy”
“girl”

3. This is CS50 AP.
an introduction to the intellectual enterprises
of computer science and the art of programming
Unit 1
Module 3
© David J. Malan, Doug Lloyd

4. variable names
in C, underscore preferred style, camel case is okay too.
variable name length is between 1 to 32 characters
can have alphabet, upper and low er case, underscore and digits.
but cannot start with a digit
no spaces in the name!!

5. data types

6. native types

7. int 50 -10 8529923 Stands for integer50
-10
Stands for integer
Holds integers between and

8. char ‘a’ ‘Z’ ‘?’ ‘\n’ Holds characters such as ‘x’ and ‘*’
Must have single quotes only Or
Since the computer stores it as an ascii, The actual ascii number

9. float
0.0
33.3

10. double long int Holds extremely large/small floating point values
To avoid math rounding problems, less discarded digits
Holds extremely large positive and negative integers

11. const

12. custom CS50 types
#include <cs50.h>

13. booleans (bool)
true
false

14. string
“A”
“Hello, world!”
“Hello, world!\n”
“This is CS50.”

15. sizes char 1 byte bool int 4 bytes float string double 8 bytes
long long
see more at

16. later this year… user-defined types
typedef, struct, enum

17. Conversion
character Description
%d integer
%f floating-point
%c character
%s string
Example: printf(“My dad’s name is %s and he is %d years old”, x, y);

18. This is CS50 AP.