1. Character Processing How characters can be treated as small integers?
How characters are stored and manipulated in a machine?
How use is made of certain standard header files?

2. Data Type char Fundamental Data Type stored in one Byte.
28=256 different combos.
Letters, Digits, Special Characters.
A character constant is written between single quotes.
char c = ‘s’;

3. In C a char has the integer value corresponding to the Binary Coding Scheme in effect (ASCII).
See page 174.
Letters: ’a’, ‘b’ ……….’z’
……….112
‘A’, ‘B’ ………’Z’
………. 90
Digits: ‘0’, ‘1’ ……….. ‘9’
Others: ‘&’ ‘+’ ………
38 43

4. printf ( “%c”, ‘a’) ? printf ( “%d”, ‘a’) ? printf ( “%c”, 98) ?
A “ %c” is used to designate the char format.
The content of the Byte can be thought of as either a character or as a small integer.
printf ( “%c”, ‘a’) ?
printf ( “%d”, ‘a’) ?
printf ( “%c”, 98) ?

5. Nonprinting and Hard-to-print Characters
Escape sequence: (see pg. 176).
‘\n’ - new line, ‘\t’ - tab
‘\\’ - get backslash
‘\”’ - get double quote mark
‘\” - get single quote mark
printf(“\“ABC\””); “ABC”
printf(“\‘ABC\’”); ‘ABC’
printf(“ \n\t This is a test”);

6. I/O of char Returns the ORDINAL VALUE of the character read.
getchar( ) reads a character from the keyboard.
int  getchar(void);
Returns the ORDINAL VALUE of the character read.
putchar( ) writes a character to the screen.
int  putchar(int c);
Functional Prototype
C is an Integer Valued Expression representing the code of the character to be output.

7. p.g. 178 char c; while (1){ c = getchar(); putchar(c);}
How Terminate? ctrl+c
ctrl+d(unix), ctrl+z(dos)
int c;
while ((c = getchar()) != EOF){
putchar(c);}

8. EOF stdio.h contains: #define EOF (-1) How interpret EOF?
Negative integer stored in 2’s complement form.
1. Take Pos value (+1)
2. Reverse Bits
3. Add 1 +1

9. Capitalize Lowercase Letters p.g. 183
#include <stdio.h>
#include <ctype.h>
int c;
while ((c = getchar()) != EOF){
if (islower(c))
putchar( toupper(c) ); }

10. # include <ctype.h>
ctype.h Header file
Contains macros & prototypes of functions that are often used when processing characters:
macros -
The C preprocessor recognizes lines of the source text that begin with ________?
The macros in ctype.h are used to test chars & includes a set of FP’s of functions that are used to convert characters.
# include <ctype.h> #

11. Use of Macros Improve I/O: # define READ(c) c = getchar( )
If (READ(c) == ‘x’)
Expand to :
If ((c = getchar( )) ==‘x’)

12. printf(“%d %d %d\n”, i, j, temp);
2) Define some often used operations:
# define SWAP(val1, val2, temp) {temp = val1; \
val1=val2; \
val2 = temp;}
int i = 4, j = 8, temp;
SWAP( i, j, temp);
printf(“%d %d %d\n”, i, j, temp);

13. Conditional Compilation Directives:
# define IBMPC 1
# if IBMPC
# include <IBM.h>
# else
# include <generic.h>
# endif
IF target machine is IBMPC use IBM specific routines else use machine independent routines
Do what if not using IBMPC _________?
Change 1 to Zero

14. Class Functions
They examine a character and tell if it belongs to a given class:
int is… (int testchar);
General Prototype

15. iscntrl- The ASCII control chars are all the values below the space(32) and the delete char(127). True if one of these-false otherwise.
isprint- Is printable, the comple ment of iscntrl. True if > 31 and < 127.
isspace- Checks for whitespace(blank(32), tab(9), line feed(10), vertical tab(11), form feed(12), carriage return(13)).

16. isgraph- All ASCII chars > 32(space) and less than 127(delete) are considered graphic characters.
isalnum- The alphabetic characters and the numeric digits are considered the alphanumeric set.
ispunct- The graphic complement of the alphanumeric chars. If testchar is > 32 (space) and < 127 (delete) but NOT an alphanumeric, it returns true.

17. isalpha- The upper and lower case alphabetic characters.
islower- Lower case letter.
isupper- Upper case letters.
isdigit- The decimal digits.
isxdigit- Test for hexidecimal digits, (0..9, a..f, A..F).