
2-5
The C Declarations
underscore is used by a programmer as a link be-
tween two words for the long identiers.
e programmer can refer to programming
example 2.3 in which the identiers are not de-
ned in lowercase but with a combination of low-
ercase and uppercase letters.
Valid identiers are as follows:
length, area, volume, sUM, Average
Invalid identiers are as follows:
Length of line, S+um, year’s
Example:
User-dened identiers are as follows:
(i) #define N 10
(ii) #define a 15
Here, ‘N’ and ‘a’ are user-dened identiers.
2.7 CONSTANTS
e constants in C are applicable to the values, which do not change during the execution of a pro-
gram. ere a ...