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:
The following are illegal (it’s your job to recognize why):
C – IDENTIFIERS EXAMPLE PROGRAM :
Int add(int p, int q);
int a,b,c ;
printf(“Enter two numbers\n”);
printf(“\n Sum of %d and %d is %d ,a,b,c”);
int add (int p, int q)
result = p + q;
|Enter two Numbers
Sum of 10 and 20 is 30