第五章

5-1

#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
",volume);

    return 0;
}


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

    result=3.1415926*r*r*h;

    return result;
}

5-2

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

不能运行

5-3

#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
",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;
}

5-4

#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("
");
        }
    }
    printf("
");
}

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;
}

5-5

#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('
');
    }
}

5-6

#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
",result_real,result_imag);
    complex_prod(real1,imag1,real2,imag2);
    printf("product of complex is %f+%fi
",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;
}

5-7

#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;
}

5-8

#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
",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;
    }

5-9

#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
",i,fact_s(i));

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

    return(f);
}

心得：打前面这个代码的时候掉了一个“ ”

那些数字就横着过去了 还以为也差不多可以过了 一看之后发现掉字了。好吧，这可不可以算是发现了这个 的用处

错误出现有点多，字数多了之后就容易掉行什么的。不过还好都能靠自己找出来，也没有浪费很多时间。