[C언어 #43] 메모리 스택 (stack) - 팩토리얼 (factorial) 재귀함수

c언어 메모리 스택 (stack) - 함수 재귀호출 (재귀함수)

ex. 팩토리얼 (factorial) 함수 재귀호출 (recursive)

 

 

기존 재귀호출 방식

/* Factorial of input number recursive */
#include <stdio.h>
 
// Get integer from terminal
int getInputNumber() {
    int num = 0;
    printf("Input an integer\n>>> ");
    scanf("%d", &num);
    return num;
}
 
// Call factorial recursively if argument is bigger than 0
int factorial(int num) {
    return num > 0 ? num * factorial(num - 1) : 1;
}
 
int main() {
    int num = getInputNumber();
    int result = factorial(num);
    printf("Factorial of %d is %d\n", num, result);
}

 

 

recursive factorial function (stack) - 팩토리얼 재귀함수

/* Factorial: recursive function */
#include <stdio.h>
 
// Get integer from terminal
int getInputNumber() {
    int num = 0;
    printf("Input an integer\n>>> ");
    scanf("%d", &num);
    return num;
}
 
// Call factorial recursively
int factorial(int num) {
    if (num == 0) return 1;
    int f = factorial(num - 1); // stack: recursive function
    return num * f;
}
 
int main() {
    int num = getInputNumber();
    int result = factorial(num);
    printf("Factorial of %d is %d\n", num, result);
}