C – Identifiers (JNNC Technologies)

Identifiers :

Identifiers are the names that are given to various program elements such as variables, symbolic constants and functions.Variable or function identifier that is called a symbolic constant name.

Identifier can be freely named, the following restrictions.

• • Alphanumeric characters ( a ~ z , A～Z , 0～9 ) and half underscore ( _ ) can only be used.
  • The first character of the first contain letters ( a ~ z , A～Z ) or half underscore ( _ ) can only be used.
  • Case is distinguishable. That is, word and WORD is recognized as a separate identifier.
  • Reserved words are not allowed. However, part of an identifier reserved words can be included.

Here are the rules you need to know:

•        Identifier name must be a sequence of letter and digits, and must begin with a letter.
•        The underscore character (‘_’) is considered as letter.
•        Names shouldn’t be a keyword (such as int , float, if ,break, for etc)
•        Both upper-case letter and lower-case letter characters are allowed. However, they’re not interchangeable.
•        No identifier may be keyword.
•        No special characters, such as semicolon,period,blank space, slash or comma are permitted

Examples of legal and illegal identifiers follow, first some legal identifiers:

float _number;

float a;

int this_is_a_very_detailed_name_for_an_identifier;

The following are illegal (it’s your job to recognize why):

float :e;

float for;

float 9PI;

float .3.14;

float 7g;

C – IDENTIFIERS EXAMPLE PROGRAM :

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#include<stdio.h> #include<conio.h> Int add(int p, int q); { int  a,b,c ; clrscr(); printf(“Enter two numbers\n”); scanf(”%d%d”,&a,&b); c=add(a,b); printf(“\n Sum of %d and %d is %d ,a,b,c”); getch(); return 0; } int add (int p, int q) { int result; result = p + q; return (result); }

Output :

Enter two Numbers 10 20 Sum of 10 and 20 is 30