Definition and declaration

[shravya]

Declaration of variable:
declaration - u can declare variables
eg:int a;
here variable 'a ' is declared as integer type that means u can store integers in variable a .
///ly if u decalre 'a' as char , you can store characters in a
eg: char a;
Definition:
In functions function definition plays an imp. role .
EG:
void fun()//fun definition
{
printf("thanx");
}

that means here we r not declaring but instead we r writing some code in a function.

[mata]

hi friends........
Declaration - u r telling the compiler in advance dat u will be using that function in future. this include d data type.name of the function and arguments
Defination - this means dat u r giving functionality or writig body for the function ,what actually a function is going to do

[niraj.kumar]

In C --- in declaration memory is not allocated
--- in definition memory get allocated