第五章

#include<stdio.h>
int main(void)
{
	double height,radius,volume;
	double cylinder(double r,double h);

	printf("Enter radius and height:");
	scanf("%lf%lf",&radius,&height);
	volume=cylinder(radius,height);
	printf("Volume=%.3f\n",volume);

	return 0;
}

double cylinder(double r,double h)
{
	double result;

	result=3.1415926*r*r*h;

	return result;
}

　　

int event(int n)
{
	if(n%2==0)
		return 1;
	else
		return 0;
}

　　

#include<stdio.h>
#include<math.h>
int main(void)
{
	double e,pi;
	double funpi(double e);

	printf("Enter e:");
	scanf("%lf",&e);
	pi=funpi(e);
	printf("pi=%f\n",pi);

	return 0;
}

double funpi(double e)

{
	int denominator,flag;
	double item,sum;

	flag=1;
	denominator=1;
	item=1.0;
	sum=0;

	while(fabs(item)>=e){
		item=flag*1.0/denominator;
		sum=sum+item;
		flag=-flag;
		denominator=denominator+2;
	}

	return sum*4;
}

　　

#include<stdio.h>
#include<math.h>

int main(void)
{
	int count,m;
	int prime(int m);

	count=0;
	for(m=2;m<=100;m++){
		if(prime(m)!=0){
			printf("%6d",m);
			count++;
			if(count%10==0)  printf("\n");
		}
	}
	printf("\n");
}

int prime(int m)
{
	int i,n;

	if(m==1)return 0;
	n=sqrt(m);
	for(i=2;i<=n;i++)
		if(m%i==0){
			return 0;
		}
		return 1;
}

　　

#include<stdio.h>
int main(void)
{
	void pyramid(int n);

	pyramid(5);

	return 0;
}
void pyramid(int n)
{
	int i,j;

	for(i=1;i<=n;i++){
		for(j=1;j<=n-i;j++)
			printf(" ");
		for(j=1;j<=i;j++)
			printf(" %d ",i);
		putchar('\n');
	}
}

　　

#include<stdio.h>
float result_real,result_imag;

int main(void)
{
	float imag1,imag2,real1,real2;
	void complex_prod(float real1,float imag1,float real2,float imag2);
	void complex_add(float real1,float imag1,float real2,float imag2);

	printf("Enter 1st complex number(real and imaginary):");
	scanf("%f%f",&real1,&imag1);
    printf("Enter 2nd complex number(real and imaginary):");
	scanf("%f%f",&real2,&imag2);

	complex_add(real1,imag1,real2,imag2);
	printf("addition of complex is %f+%fi\n",result_real,result_imag);
	complex_prod(real1,imag1,real2,imag2);
	printf("product of complex is %f+%fi\n",result_real,result_imag);

	return 0;
}

void complex_add(float real1,float imag1,float real2,float imag2)
{
	result_real=real1+real2;
	result_imag=imag1+imag2;
}

void complex_prod(float real1,float imag1,float real2,float imag2)
{
	result_real=real1*real2-imag1*imag2;
	result_imag=real1*imag2+real2*imag1;
}

　　

#include<stdio.h>
int x;
int f();
int main(void)
{
	int a=1;

	x=a;
	a=f();
	{
		int b=2;
		b=a+b;
		x=x+b;
	}
	printf("%d %d",a,x);

	return 0;
}

int f()
{
	int x=4;

	return x;
}

　　

#include<stdio.h>
float cash;
int main(void)
{
	int choice;
	float value;
	void income(float number),expend(float number);

	cash=0;
	printf("Enter operate choice(0--end,1--income,2--expend):");
	scanf("%d",&choice);
	while(choice!=0){
		if(choice==1||choice==2){
			printf("Enter cash value:");
			scanf("%f",&value);
			if(choice==1)
				income(value);
			else
				expend(value);
			printf("current cash:%.2f\n",cash);
		}
		printf("Enter operate choice(0--end,1--income,2--expend):");
		scanf("%d",&choice);
	}

	return 0;
}

void income(float number)
{
	cash=cash+number;
}

void expend(float number)
{
	cash=cash-number;
}

　　

#include<stdio.h>
double fact_s(int n);
int main(void)
{
	int i,n;
	printf("Input n:");
	scanf("%d",&n);
	for(i=1;i<=n;i++)
		printf("%3d!=%.0f\n",i,fact_s(i));

	return 0;
}
double fact_s(int n)
{
	static double f=1;
	f=f*n;

	return(f);
}