Recursion is a programming technique where a function calls itself, which is exemplified by a recursive function to calculate factorials. The document discusses how this process utilizes stack memory to handle multiple calls and provide results. An example is given to illustrate the factorial calculation through recursive calls.

1. What is Recursion?

2. The function that calls itself is called as recursive
function and the technique is known as recursion.
Example-: int sample()
{
sample(); //recursion
}

3. int main()
{
printf(“Start”);
main();
printf(“End”);
}
Stack Memory
main()
printf(“Start”);
main();
main()
printf(“Start”);
main();
main()
printf(“Start”);
main();
main()
printf(“Start”);
main();
Execution
Terminated

4. Factorial using
Recursion

5. Stack Memory
if(3==0)
X
else
res=3*fact(2);
return res;
fact(n==3)
if(2==0)
X
else
res=2*fact(1);
return res;
fact(n==2)
if(1==0)
X
else
res=1*fact(0);
return res;
fact(n==1)
if(0==0)
res=1
return res;
fact(n==0)
n=3,res;
fact(3);
Output:6
main()
1
12
6