How does variable declaration in C++ differ from traditional C (before C99) with respect to where inside a block variables may be declared?

Introduction / Context:
The rules for where variables can be declared in a block are slightly different between traditional C and C++. This difference often appears in interview questions, because it affects coding style, readability, and how easily developers can introduce variables close to where they are used. Knowing the historical distinction helps you understand older C code and appreciate the more flexible style encouraged in C++ and modern C standards.

Given Data / Assumptions:

• We are comparing classic C (for example C89) with C++.
• The focus is on the position of variable declarations inside a function or compound statement.
• Global and file scope declarations are not the main concern here.
• We assume pre C99 C rules, which are stricter than modern C in this regard.

Concept / Approach:
In traditional C (such as C89), all variable declarations inside a block had to appear before any executable statements. That means you would typically see a cluster of declarations at the top of a function or code block, followed by the statements that use those variables. C++ relaxed this rule and allows variables to be declared at any point in a block, as long as they are declared before they are used. This allows declarations to be placed closer to their first use, which can make code easier to read and maintain. Modern C (C99 and later) adopted similar flexibility, but many exam questions still refer to the original C89 behaviour when contrasting with C++.

Step-by-Step Solution:
Step 1: Recall that in older C standards, a function body begins with a series of declarations followed by statements, and declarations cannot appear after statements in the same block. Step 2: Recognise that this forces programmers to declare all local variables at the top of a function or block, even if they are used only in a narrow portion of the code. Step 3: In C++, the language standard explicitly allows you to introduce a new variable at almost any point in a block as long as it is declared before its first use. Step 4: This means you can write a loop or conditional and declare variables directly inside those structures, which improves locality and clarity. Step 5: Comparing these behaviours, the correct description is that C++ allows declarations anywhere in the block, whereas classic C requires them at the beginning.

Verification / Alternative check:
Consider a small example. In C++, code such as for (int i = 0; i < n; ++i) { int temp = compute(i); use(temp); } is valid and idiomatic. In C89, declaring int temp inside the body after other statements would not be allowed; instead, you would need to declare temp at the top of the block before any statements. This practical example shows how C++ rules are more flexible and confirms the difference described in the correct option.

Why Other Options Are Wrong:
Option B: Reverses the roles of C and C++ and therefore does not match the actual language rules. Option C: Claims that both languages require all variables to be global, which is false because both languages support local variables inside functions. Option D: States there is no difference, which ignores the well known historical distinction between traditional C and C++ variable declaration placement.

Common Pitfalls:
A common pitfall is to forget that C99 changed the rules for C, allowing mixed declarations and code similar to C++. Because of this, some learners think there has never been any difference. Exam questions, however, often specifically refer to classic C behaviour. Another mistake is to think that placing declarations anywhere is always best; while it can improve clarity, overusing this freedom can also make code harder to scan. The key point for this question is simply the historical rule: C++ allowed declarations anywhere in a block from the beginning, whereas older C required them at the top.

Final Answer:
In summary, C++ allows variables to be declared anywhere inside a block, while C requires declarations at the beginning of a block in the traditional standard.