C Tutorials
| Constants |
The constants refer to fixed values that the program may not alter during its execution. These fixed values are also called literals. Constants can be of any of the basic data types like an integer constant, a floating constant, a character constant, or a string literal. There are also enumeration constants as well. The constants are treated just like regular variables except that their values cannot be modified after their definition.
| Integer Literals |
An integer literal can be a decimal, octal, or hexadecimal constant. A prefix specifies the base or radix: 0x or 0X for hexadecimal, 0 for octal, and nothing for decimal. Here are some examples of integer literals:
85 /* decimal */
0213 /* octal */
0x4b /* hexadecimal */
30 /* int */
30u /* unsigned int */
30l /* long */
30ul /* unsigned long */
| Floating Point Literals |
A floating-point literal has an integer part, a decimal point, a fractional part, and an exponent part. You can represent floating point literals either in decimal form or exponential form. Here are some examples of floating-point literals:
3.14159 /* Legal */
314159E-5L /* Legal */
510E /* Illegal: incomplete exponent */
210f /* Illegal: no decimal or exponent */
| Character Constants |
Character literals are enclosed in single quotes e.g., 'x' and can be stored in a simple variable of char type. There are certain characters in C when they are proceeded by a back slash they will have special meaning and they are used to represent like newline (\n) or tab (\t). Here you have a list of some of such escape sequence codes:
| Escape Sequence | Meaning | Escape Sequence | Meaning |
| \\ | \ character | \f | Form Feed |
| \' | ' character | \n | New Line |
| \" | " character | \r | Carriage Return |
| \? | ? character | \t | Horizontal Tab |
| \a | Alter or Bell | \v | Vertical Tab |
| \b | Backspace | \ ooo | Octal number of 1 to 3 digits |
| String Literals |
String literals or constants are enclosed in double quotes "". A string contains characters that are similar to character literals: plain characters, escape sequences, and universal characters.
| Const Keyword |
const can be prefix to declare constant with specific type.
#include <stdio.h>
int main()
{
const int LENGTH = 10;
const int WIDTH = 5;
const char NEWLINE = '\n';
int area;
area = LENGTH * WIDTH;
printf("value of area : %d", area);
printf("%c", NEWLINE);
return 0;
}
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