C recursion
Recursion refers to the method of using the function itself in the definition of the function.
For example:
Once upon a time there was a mountain, and there was a temple in the mountain. There was an old monk in the temple, and he was telling stories to the young monk! What's the story? "Once upon a time there was a mountain, and there was a temple in the mountain. There was an old monk in the temple, and he was telling a story to the young monk! What is the story? 'Once upon a time, there was a mountain. There was a temple in the mountain. There was an old monk in the temple. He was telling a story to the young monk. Tell a story to the little monk! What is the story? ...'"
The syntax format is as follows:
void recursion(){
recursion(); /* 函数调用自身 */}int main(){
recursion();}C language supports recursion, that is, a function can call itself. But when using recursion, programmers need to pay attention to defining a condition for exiting from the function, otherwise it will enter an infinite loop.
Recursive functions play a vital role in solving many mathematical problems, such as calculating the factorial of a number, generating the Fibonacci sequence, and so on.
Factorial of a Number
The following example uses a recursive function to calculate the factorial of a given number:
#include <stdio.h>double factorial(unsigned int i){ if(i <= 1) { return 1; } return i * factorial(i - 1);}int main(){ int i = 15;
printf("%d 的阶乘为 %f\n", i, factorial(i)); return 0;}When the above code is compiled and executed, It will produce the following results:
15 的阶乘为 1307674368000.000000
Fibonacci Sequence
The following example uses a recursive function to generate the Fibonacci Sequence for a given number:
#include <stdio.h>int fibonaci(int i){ if(i == 0) { return 0; } if(i == 1) { return 1; } return fibonaci(i-1) + fibonaci(i-2);}int main(){ int i; for (i = 0; i < 10; i++) {
printf("%d\t%n", fibonaci(i)); } return 0;}When the above code is compiled and executed, it produces the following results:
0112358132134
