Rules for constructing variables in C Language

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Variables in C are entities whose value keeps on changing throughout the program execution. As we all know, data is stored in the memory of the computer. Actually, data is not stored in the variable. A variable is the name given to the memory location. A variable name is an entity that points to a particular memory location.

Rules for constructing variables in C

  1. A Variable name consists of any combination of alphabets, digits and underscores. Some compiler allows variable names whole length could be up to 247 characters. Still it would be safer to stick to the rule of 31 characters. Please avoid creating long variable name as it adds to your typing effort
  2. The first character of the variable name must either be alphabet or underscore. It should not start with the digit
  3. No commas and blanks are allowed in the variable name
  4. No special symbols other than underscore are allowed in the variable name

We need to declare the type of the variable name before making use of that name in the program. Type declaration can be done as follows:

To declare a variable as integer, follow the below syntax:

int variable_name;

Here int is the type of the variable named variable_name. β€˜int’ denotes integer type.

Following are the examples of type declaration statements:


int p, n;
float r;

To learn more about variables in C, visit – Variable, Constant and Keyword in C

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33 Responses

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  8. LearnCOnline says:

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  9. abhinav says:

    can u explain int variable_name nd giv another eg

  10. LearnCOnline says:

    E.g: int flag;
    In the above declaration, flag is a variable that with hold an integer value.

    we can set the value of the above variable as follows:

    flag = 0;

    Here value 0 gets stored in the variable flag.

  11. Anonymous says:

    why cannot the variable name start with a number?

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  18. Juhi Kumari says:

    as told no special character is allowed.
    Why $jd is a variable?

  19. Anonymous says:

    try to create a variable with name $a, it gets compiled using gcc

  20. Anonymous says:

    nice piece

  21. Anonymous says:

    helped a lot

  22. anoop says:

    wht r different rules to define a variable with example

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  1. October 7, 2020

    […] Here, data-type represents any valid C data-type. E.g. int, char, float, double etc. variable_name can be any valid name satisfying rules for constructing variables in C. […]

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