忙里偷闲( ˇˍˇ )闲里偷学【C语言篇】—

一、for和while等价替换

int i = 1;

for (i; i<=100; i++){

	sum = sum + 1;

}

int i = 1;

while(i<=100){

	sum = sum + 1;

	i++;

}

二、从键盘输入一个数字，如果该数字是回文数，则返回yes,否则返回no

回文数：正着写倒着写一样的数

# include<stdio.h>

int main(){

	int val, m, sum=0;

	printf("请输入您需要判断的数字：");

	scanf("%d", &val);

	m = val;

	while(m){

		sum = sum * 10 + m%10;

		m /= 10;

	}

	if(sum==val){

		printf("yes\n");

	}else{

		printf("no\n");

	}

	return 0;

}

三、斐波拉契数列

1 2 3 5 8 13 21 34.....
从第三项开始每一项是前两项的和

# include <stdio.h>

int main(void){

	int n;

	int f1, f2, f3;

	int i;

	f1 = 1;

	f2 = 2;

	printf("请输入您需要求得项的序列：\n");

	scanf("%d", &n);

	if(1==n){

		f3 = 1;

	}else if(2==n){

		f3 = 2;

	}else{

		for(i=3; i<=n; i++){

			f3 = f1 + f2;

			f1 = f2;

			f2 = f3;

		}

	}

	printf("%d\n", f3);

	return 0;

}

四、do....while....实现一元二次方程

# include <stdio.h>

# include <math.h>

int main(void)

{

	double a, b, c;

	double delta;

	double x1, x2;

	char ch;

	do

	{

		printf("请输入一元二次方程的三个系数:\n");

		printf("a = ");

		scanf("%lf", &a);

		printf("b = ");

		scanf("%lf", &b);

		printf("c = ");

		scanf("%lf", &c);

		delta = b*b - 4*a*c;

		if (delta > 0)

		{

			x1 = (-b + sqrt(delta)) / (2*a);

			x2 = (-b - sqrt(delta)) / (2*a);

			printf("有两个解，x1 = %lf, x2 = %lf\n", x1, x2);

		}

		else if (0 == delta)

		{

			x1 = x2 = (-b) / (2*a);

			printf("有唯一解，x1 = x2 = %lf\n", x1, x2);

		}

		else

		{

			printf("无实数解!\n");

		}

		printf("您想继续么(Y/N): ");

		scanf(" %c", &ch);  //%c前面必须得加一个空格 原因略

	} while ('y'==ch || 'Y'==ch);

	return 0;

}

巴特西

忙里偷闲( ˇˍˇ )闲里偷学【C语言篇】——（4）for == while ?

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