Constants in C Programming
- 1. Constants N.V.Raja Sekhar Reddy C-Programming Tutorials www.programming9.com
- 2. What to Discuss? What is a Constant ? Types of Constants in C Integer Constants Real Constants Character Constants String Constants 2 www.programming9.com
- 3. What is a Constant? www.programming9.com3 Constant is a value that cannot change during the execution of a program. Like variables constants have data types.
- 4. Syntax www.programming9.com4 const data_type variable_name; (or) data_type const variable_name; You can also define as follows #define pi 3.14
- 5. Types of Constants in C www.programming9.com5 Integer Constants Real Constants Character Constants String Constants
- 6. Integer Constants www.programming9.com6 C integer constant is a decimal, octal (Value starts with 0) or hexadecimal number (Value starts with 0x). Integer constants are always positive until you specify a negative(-) sign. Decimal Constants Octal Constants HexaDecimal Constants 10 012 0xA 1024 02000 0x400 12789845 060624125 0xC32855
- 7. Example Program www.programming9.com7 #include<stdio.h> void main() { const int a=10; //Decimal int const b= 012; //Octal const int c=0xA; //Hexadecimal printf(" %d n %d n %d",a,b,c); } OUTPUT: it prints 10 10 10 as output.
- 8. Real Constants www.programming9.com8 The default form of real constant is double and it must have a decimal point. You can represent the negative numbers in real constants. It may be in fractional form or exponential form. Ex: 3.45, -2.58, 0.3E-5 (equal to 0.3 x 10-5 ) Representation Value Type 0 0.0 double 6.77 6.77 double -6.0f -6.0 float 3.1415926536L 3.1415926536 long double
- 9. Character Constants www.programming9.com9 Character Constants must be enclosed with in single quotes. We use escape character along with the character. The escape character says that it is not a normal character and do something. ASCII Character Symbol Alert(bell) 'a' Null character '0' Backspace 'b' Horizontal Tab 't' New line 'n' Vertical tab 'v' Form Feed 'f' Carriage Return 'r' Single Quote ''' Double Quote '"' Backslash ''
- 10. String Constants www.programming9.com10 A string constant is a sequence of characters enclosed in a double quotes. Examples: "" // Null String "programming9" // a full string with 12 characters "wel come" // string with 8 characters
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