In C programming, when you write a real number constant such as 3.14 without any suffix, by default it is treated as which data type?

Introduction / Context:
In languages like C and C plus plus, numeric literals used in source code have default types if no suffix is provided. For example, whole numbers such as 10 are usually considered int by default, and real numbers such as 3.14 are treated as a particular floating point type. Knowing these defaults is important for understanding precision, memory usage, and function overloading. This question asks what type a real number constant is treated as by default when you do not explicitly add any suffix in C.

Given Data / Assumptions:

• The language context is C programming.
• We are dealing with a real number constant, for example 3.14 or 0.5.
• No suffix such as f, F, l, or L is attached to the constant.
• The options are integer, float, double, and long double.

Concept / Approach:
In the C language, floating point constants without suffix are of type double by default. If you want a literal of type float, you add the suffix f or F, for example 3.14f. If you want a long double, you add l or L, such as 3.14L. Integer constants are a separate category used for whole numbers without fractional parts. Therefore, when you write a real number constant with a decimal point and no suffix, the compiler interprets it as a double, not as float, long double, or integer.

Step-by-Step Solution:
Step 1: Identify that the literal is a real number with a decimal point, such as 3.14. Step 2: Recall C rules for floating point constants. In C, a floating constant without any suffix has type double. Step 3: Consider how to write a float literal. To get a float, you must use a suffix, for example 3.14f or 3.14F. Step 4: Consider how to write a long double literal. To get a long double, you must use a suffix L or l, such as 3.14L. Step 5: Confirm that integer is irrelevant because the presence of a decimal point makes it a floating constant. Step 6: Conclude that the default type is double.

Verification / Alternative check:
The C standard and most textbooks state that floating constants without suffix are of type double, while those with suffix f or F are of type float and those with suffix l or L are long double. If you write code such as float x = 3.14;, the compiler will usually convert the double literal 3.14 to float, sometimes issuing a warning depending on settings. This confirms that the literal itself is double. Integer constants such as 10 or 42 do not use decimal points and are usually of type int by default, which is a separate rule.

Why Other Options Are Wrong:
Option A (Integer): Integer types represent whole numbers without fractional parts; a real constant like 3.14 is not an integer constant. Option B (Float): Float requires an explicit suffix f or F; without that suffix, the compiler uses double. Option D (Long double): Long double requires an explicit suffix l or L; it is not the default type.

Common Pitfalls:
A common misunderstanding is to assume that float is the default floating type because it has the same name as the concept of floating point numbers. Students may also overlook the significance of suffixes and not realise that 3.14 and 3.14f are different types. To avoid mistakes, remember the simple rule: in C, floating constants without a suffix are double by default, f or F gives float, and L or l gives long double.

Final Answer:
In C programming, a real number constant written without any suffix is treated by default as a Double.