Integer Real Character String

Decimal integer◦ Consist of 0 through 9, +, -

Octal integer◦ Consist of 0 through 7, with a leading 0

Hexadecimal integer◦ Consist of 0 to 9, and a through f preceded by

0x or 0X

The largest integer value is machine-dependent

Qualifiers◦ U or u: unsigned integer◦ l or L: long integer ◦ UL or ul: unsigned long integer◦ Short integer

short is no longer than int and that long is no shorter than int.

Example2.1 Representation of integer constants on a 16-bit computer.

#include<stdio.h>main(){

printf("Integer values\n\n");printf("%d %d %d\n",32767,32767+1,32767+10);printf("\n");printf("Long integer values\n\n");printf("%ld %ld %ld\n",32767L,32767+1L, 32767+10L);

}

(1) decimal point◦ Consist of 0 through 9, . ,+ , -◦ 3.14159, .94 , -.58 , +1.234

(2)Exponential notationmantissa e exponent

◦ .56e3 2.3e-3 -2.3E-3◦ The exponent must be an integer number

Suffixes f or F indicate a float constant L or l indicate a long double “Default values of constants” on page35

Floating-Point Round-off Errors Take a number, add 1 to it, and subtract the

original number. What do you get? You get 1. A floating-point calculation, may give another answer:

A character enclosed within ‘ ’◦ ‘6’ ‘=‘ ‘;’ ‘ ‘◦ Character constants have integer values, For

example◦ ‘a’ and 97◦ ‘0’ and 48

Backslash character constants◦ Table2.5 on page28◦ ‘\ooo’ and ‘\xhh’

a sequence of characters enclosed in “ ”, for example◦ “hello” “34” “+()” “x” “\n”

“x” and ’x’

A variable is data name that may be used to store a data value.◦ Variable names correspond to locations in the

computer's memory◦ Every variable has a name, a type, a size and a

value◦ Whenever a new value is placed into a variable, it

replaces (and destroys) the previous value◦ Reading variables from memory does not change

them

The declaration of variables must be done before they are used.

declaration formdata-type v1,v2,…,vn;

for example◦ int count;◦ float sum;◦ double ratio;◦ char ch;

To initialize a variable means to assign it a starting, or initial, value.

In C, this can be done as part of the declaration.

char ch=‘ ’; int cows = 32, int dogs, cats = 94;