Constant in c programming language
- What is a Constant?
A constant is a value that cannot be modified once it is defined.
Example:
C
10
3.14
'A'
"Hello"
🔹 Types of Constants in C
C constants are mainly divided into:
- Integer Constants
- Floating (Real) Constants
- Character Constants
- String Constants
- Enumeration Constants
- Symbolic Constants
1️⃣ Integer Constants
These are whole numbers (without decimal point).
➤ Types of Integer Constants
(a) Decimal Integer
Base 10 numbers
Digits: 0–9
Example:
C
10
-25
500
(b) Octal Integer
Base 8 numbers
Starts with 0
Digits: 0–7
Example:
C
075
012
(c) Hexadecimal Integer
Base 16 numbers
Starts with 0x or 0X
Digits: 0–9 and A–F
Example:
C
0x1A
0XFF
2️⃣ Floating (Real) Constants
These contain decimal points or exponential form.
➤ Types:
(a) Fractional Form
C
3.14
-0.98
10.0
(b) Exponential Form
C
1.5e3 // 1.5 × 10³
2E-2 // 2 × 10⁻²
3️⃣ Character Constants
A single character enclosed in single quotes ' '.
Example:
C
'A'
'5'
'#'
➤ Escape Sequences (Special Characters)
Escape Meaning
\n New line
\t Tab
\b Backspace
\0 Null character
Example:
C
'\n'
'\t'
4️⃣ String Constants
A group of characters enclosed in double quotes " ".
Example:
C
"Hello"
"India"
"123"
👉 String always ends with a null character \0.
5️⃣ Enumeration Constants
Defined using enum keyword.
Example:
C
enum day {MON, TUE, WED};
Here:
MON = 0
TUE = 1
WED = 2
6️⃣ Symbolic Constants
These are names given to constants using:
(a) #define
C
#define PI 3.14
#define MAX 100
(b) const keyword
C
const int x = 10;
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