《Programming Abstractions In C》学习第61天，p184-p195总结。

一、技术总结

1.mutual recursion

2.natural number

(1)定义

p184, If you limit the domain of possible values to the set of natural numbers,which are defined simply as the set of nonnegative integers.

3.最大公约数

/*
 * p191. 3. The greatest common divisor(g.c.d) of two nonnegative integers is the
 * largest integer that divides evenly into both. In the third century B.C., the
 * Greek mathematician Euclid discovered that the greatest common divisor of x
 * and y can always be computed as follows:
 *
 * If x is evenly divisible by y, then y is the greatest common divisor.
 * Otherwise, the greatest common divisor of x and y is always equal to the
 * greatest common divisor of y and the remainder of x divided by y.
 *
 * Use Euclid insight to write a recursive function GCD(X, Y) that computes the
 * greatest common divisor x and y.
 */
#include <stdio.h>

int gcd(int x, int y);

/*
 * function: gcd
 * Usage: int(x, y)
 * ------------
 */
int gcd(int x, int y) {
    if (x % y == 0) {
        return y;
    }
    return gcd(y, x % y);
}


int main() {
    int result;
    result = gcd(16, 28);
    printf("GCD=%d\n", result);  // GCD=4
    return 0;
}

二、英语总结

1.holistic是什么意思？

答：

(1)holistic: holism + -istic。adj. treat the whole of sth and not just a part(整体的)。

(2)holism: holos("whole"，来自于“*sole”，完整的) + -ism(word-forming element making nouns implying a practice, system, doctrine, etc. 构成词的元素，暗示实践、制度、学说等)。u. the belief that each thing is a whole that is more important the parts that make it up，整体论。

(3)-istic: adjectival word-forming element(构成形容词的元素)。

(4)示例：p185, Maintain a holistic perspective(保持整体的观点)。

2.philosophical是什么意思?

(1)philosophical: philosophy + -ical。adj. relating to the study of philosophy(哲学的)。

(2)philosophy: philo-("loving") + sophia("knowledge, wisdom")，哲学。

3.devote是什么意思？

答：de-(down from，away from, 离开) + vow(to vow“make a promise to do sth, 发誓”)，即as if by vow。

(1) vt. to use sth for a particular purpose（使用）。p185，In Chapter 2 of The Art and Science of C, I devote one section to the philosophical concepts of holism and reductionnism(在《在C语言的科学与艺术》第二章，我专门用一节来介绍整体论与还原论这两个哲学概念。)

4.odds are good是什么意思？

答：

(1)odds: n. the probalility that a particular thing will or will not happend(可能性)。

(2)odds are good: There is a high probability that it will happen(可能性很大)。

(3)示例：p185,After all, when you write a program, the odds are good--even if you are an experienced programmer--that your program won't work the first time。