第2章课后编程题全部答案

自己练习时手写，难免会有些疏忽遗漏等各种各样问题，错误之处还请指出。

但这些代码确实已通过编译，实现了书上的输出结果，还希望能给抱有期待之人作为个小参考。

后续章节慢慢更新中……

2.1

#include <stdio.h>
 
int main (void)
{
	printf ("       *\n");
	printf ("      *\n");
	printf ("     *\n");
	printf ("*   *\n");
	printf (" * *\n");
	printf ("  *\n");
	
	return 0;
} 

2.2&2.3

#include <stdio.h>
 
#define pi 3.14
 
int main (void) 
{
	int r = 0;
	
	scanf ("%d", &r);
	
	printf ("%f", 4.0f/3.0f*pi*r*r*r);
	
	return 0;
}

2.4

#include <stdio.h>
 
int main (void)
{
	float a;
	
	printf ("Enter an amount:");
	scanf ("%f", &a);
	
	printf ("With tax added: $%.2f", a*1.05);
	
	
	return 0;
}

2.5&2.6

#include <stdio.h>
 
int main (void)
{
	int x, y;
	
	scanf ("%d", &x);
	
	y = ((((3*x+2)*x-5)*x-1)*x+7)*x-6;
	
	printf ("%d", y);
	
	return 0;
}

2.7

#include <stdio.h>
 
int main (void)
{
	int money;
	int num20, num10, num5, num1;
	
	printf ("Enter a dollar amount:");
	scanf ("%d", &money);
	
	num20 = money / 20;
	money = money - 20*num20;
	num10 = money / 10;
	money = money - 10*num10;
	num5 = money / 5;
	num1 = money % 5;
	
	printf ("$20 bills: %d\n", num20);
	printf ("$10 bills: %d\n", num10);
	printf (" $5 bills: %d\n", num5);
	printf (" $1 bills: %d\n", num1);
	
	return 0;
}

2.8

#include <stdio.h>
 
int main (void)
{
	float money, rate, payment; 
	
	printf ("Enter amount of loan:");
	scanf ("%f", &money);
	printf ("Enter interest rate:");
	scanf ("%f", &rate);
	printf ("Enter monthly payment:");
	scanf ("%f", &payment);
	
	printf ("Balance remaining after first payment:%.2f\n", money=((money-payment)+(money*0.01*rate/12)));
	printf ("Balance remaining after second payment:%.2f\n", money=((money-payment)+(money*0.01*rate/12)));
	printf ("Balance remaining after third payment:%.2f\n", money=((money-payment)+(money*0.01*rate/12)));
	
	return 0;
}