Variables and Constants in c:
Variables and Constants in c are crucial topics to understand in c language because lot of people here are beginning programming. These Variables and Constants in c are tokens which represent contents r flowing part of program.
Variables:
Variable is name of memory location which contain value of specific type.
Value of variable can be changed during execution of program.
Constants:
Fixed values which do not change during execution of program are called constants . constants in c can be categorized in following types.
Declaring constants:
1. Decimal Integer constants:
const int i=12;
%d or %i format specifier is used to print decimal integer value with in printf function.
2. Octal integer constants:
const int i=012;
Any constant preceded by 0 is regarded as octal integer constant . To print octal value %o format specifier is used.
3. Hexadecimal constants:
const int i=0x12;
Any constant preceded by 0x or 0X is regarded as Hexadecimal Integer constant. To print Hexadecimal value %x format specifier is used in printf function.
4. Real constants:
const float a=3.14;
We can use %f,%e or %E format specifier within printf function to print real values.
5. Character constants:
const char ch='d';
Any constant enclosed in single quotes is character constants. %c format specifier is used to print single character .
6. String constants
const char[5]="Ravin";
Constant enclosed in double quotes is called String constant. We can use %s format specifier to print string value.
const int i=12;
printf("%d",i);
printf("%o",i);
printf("%x",i);
const char ch='z';
printf("%c",ch);
const char name[5]="Ravin";
printf("%s",name);
7. Escape Sequence:
Escape sequence is special character constant Which consistof two character and used with output function to print invisible pattern like newline and backspace
List of escape sequence :
‘\n‘: Backspace
‘\b': form feed
‘\f‘: New line
‘\r‘: carrige return
‘\t‘: horizontal tab
‘\v‘:vertical tab
‘\'‘: to print single quotes
‘\\‘:to print back slash
‘\0‘: null
‘\"‘: To print double quotes
Important :
If you try to reassign a value to constant , you will encounter compile time error saying “Cannot modify a const object”. For example see code below:
void main(){
const int i=12;
printf("%d",i);
i=15;
printf("%d",i);
}
When you compile this code you will get error.
I hope you have got clear idea about variables and constants after reading this post. If you have any query comment below and take part in discussion.
