Why Can't Variable Names in C Start with a Number?

Why Variable Names Cannot Start with Numbers

When assigning variable names in C , naming conventions prohibit the use of numbers as the first character. This restriction stems from the need to distinguish between variable names and numeric values.

If variable names were allowed to begin with numbers, it would create a conflict with the syntactic rules for numeric constants. For instance, the following code would be invalid:

int 17 = 497; // Error: Invalid variable name

Here, the compiler would interpret "17" as a numeric constant instead of a variable name, leading to a compilation error.

Similarly, allowing numbers as initial characters for variable names would make it difficult to differentiate between variable identifiers and numbers in code expressions:

int 42 = 6 * 9; // Error: Ambiguous expression

In this example, the compiler would struggle to determine if "42" is a variable name or a literal value.

Furthermore, if variable names could start with numbers, strings of digits would also be valid identifiers, potentially leading to naming conflicts and code readability issues:

String 1111 = "Totally text"; // Error: Invalid variable name

To avoid such confusion and ambiguity in code, C restricts variable names from starting with numbers, ensuring that variable identifiers can be easily distinguished from numeric values and expressions.

The above is the detailed content of Why Can't Variable Names in C Start with a Number?. For more information, please follow other related articles on the PHP Chinese website!