【C Primer Plus第九章课后编程题】

9.1

#include<stdio.h>
#include<stdlib.h>

double min (double x,double y);

int main (void)
{
    
    double x,y;

    printf("Please enter two numbers:");
    scanf("%lf %lf",&x,&y);

    printf("The smaller is %lf", min(x,y)); 

    system("Pause");

    return 0;
}

double min (double x,double y)
{
    
    return (x>y)?y:x;
}

9.2

#include<stdio.h>
#include<stdlib.h>

void chline(char ch,int i,int j);

int main (void)
{
    

    char ch;
    int i,j;

    printf("Please enter a char:");
    scanf("%c",&ch);
    printf("Please enter the row and line you want print:");
    scanf("%d %d",&i,&j);

    chline(ch,i,j);

    system("Pause");

    return 0;
}

void chline(char ch,int i,int j)
{
    
    int row,line;

    for (row= 0;row<j;row++)
    {
    
        for (line=0;line<i;line++)
        {
    
            printf("%c",ch);
        }
        printf("\n");
    }
    
}

9.3

#include<stdio.h>
#include<stdlib.h>

void chline(char ch,int i,int j);

int main (void)
{
    

    char ch;
    int i,j;

    printf("Please enter a char:");
    scanf("%c",&ch);
    printf("Please enter the row and line you want print:");
    scanf("%d %d",&i,&j);

    chline(ch,i,j);

    system("Pause");

    return 0;
}

void chline(char ch,int i,int j)
{
    
    int row,line;

    for (row= 0;row<j;row++)
    {
    
        for (line=0;line<i;line++)
        {
    
            printf("%c",ch);
        }
        printf("\n");
    }
    
}

9.4

#include<stdio.h>
#include<stdlib.h>

double average(double a,double b);

int main (void)
{
    
    double a,b;

    printf("Please enter two numbers:");
    scanf("%lf %lf",&a,&b);

    printf("%lf",1/average(a,b));


    system("Pause");

    return 0;
}

double average(double a,double b)
{
    
    double average;

    average=1/a+1/b;

    return average;
}

9.5

#include<stdio.h>
#include<stdlib.h>

double larger_of(double x,double y);

int main (void)
{
    
    double x,y;

    printf("Please enter two numbers:\n");
    scanf("%lf %lf",&x,&y);

    printf("%lf",larger_of(x,y));
    system("Pause");

    return 0;
}

double larger_of(double x,double y)
{
    
    (x>y)?(y=x):(x=y);

    return x;
}

9.6

#include<stdio.h>
#include<stdlib.h>

double arrange(double* x,double* y,double* z);

int main (void)
{
    
    double x,y,z;

    printf("Please enter three numbers:");
    scanf("%lf %lf %lf",&x,&y,&z);
    arrange(&x,&y,&z);
    printf("%lf %lf %lf",x,y,z);

    system("Pause");

    return 0;
}

double arrange(double* x,double* y,double* z)
{
    
    double temp;

    if (*x>*y)
    {
    
        temp=*x;
        *x=*y;
        *y=temp;
    }
    if (*x>*z)
    {
    
        temp=*x;
        *x=*z;
        *z=temp;   
    }
    if (*y>*z)
    {
    
        temp=*y;
        *y=*z;
        *z=temp;
    }
    
    
}

9.7

#include<stdio.h>
#include<ctype.h>
#include<stdlib.h>

int  posion(int ch);

int main (void)
{
    
    int ch;
    int temp;

    printf("Please enter a letter:");
    while ((ch=getchar())!=EOF)
    {
    
       while (getchar()!='\n')
            continue;

        temp=posion(ch);
        
        if (temp==-1)
        {
    
            printf("It is not a letter:%d\n",temp);
        }
        else
        {
    
            printf("It is the %d letter in alphabet\n",temp);
        }              
    }
    
    system("Pause");

    return 0;
}

int posion(int ch)
{
    
    int letter;

    if (isupper(ch))
    {
    
        letter=ch-'A'+1;
    }
    else if(islower(ch))
    {
    
        letter=ch-'a'+1;
    }
    else
    {
    
        return -1;
    }

    return letter;
}

9.8

#include<stdio.h>
#include<stdlib.h>

double power(double n,int p);

int main (void)
{
    
    double x,xpow;
    int exp;

    printf("Enter a number and the positive integer power");
    printf(" to which\nthe number will be raised.Enter q");
    printf(" to quit.\n");
    while (scanf("%lf%d",&x,&exp)==2)
    {
    
        xpow=power(x,exp);
        printf("%.3g to the power %d is %.5g\n",x,exp,xpow);
        printf("Enter next pair of numbers or q to quit.\n");
    }
    printf("Hope you enjoyed thie power trio -- bye!\n");

    system("Pause");

    return 0;
}

double power(double n,int p)
{
    
    double pow=1;
    int i;

    if ((n==0)&&(p==0))
    {
    
        return 0;
    }
    else if (p==0)
    {
    
        return 1;
    }
    else if (p>0)
    {
    
        for (i = 1; i <= p; i++)
        {
    
            pow*=n;
        }
        return pow;
    }
    else
    {
    
        for (i = 1; i <= -p; i++)
        {
    
            pow*=1/n;
        }
        return pow;
    }
    
    
}

9.9

#include<stdio.h>
#include<stdlib.h>

double power(double n,int p);

int main (void)
{
    
    double x,xpow;
    int exp;

    printf("Enter a number and the positive integer power");
    printf(" to which\nthe number will be raised.Enter q");
    printf(" to quit.\n");
    while (scanf("%lf%d",&x,&exp)==2)
    {
    
        xpow=power(x,exp);
        printf("%.3g to the power %d is %.5g\n",x,exp,xpow);
        printf("Enter next pair of numbers or q to quit.\n");
    }
    printf("Hope you enjoyed thie power trio -- bye!\n");

    system("Pause");

    return 0;
}

double power(double n,int p)
{
    
    double pow=1;
    int i;

    if ((n==0)&&(p==0))
    {
    
        return 0;
    }
    else if (p==0)
    {
    
        return 1;
    }
    else if (p>0)
    {
    
        return n*power(n,p-1);
    }
    else
    {
    
        return power(n,p+1)/n;
    }
    
    
}

9.10

#include<stdio.h>
#include<stdlib.h>

void to_base_n(unsigned long num,int n);

int main (void)
{
    
    unsigned long number;
    int n;

    printf("Enter two integers (q to quit):\n");
    while (scanf("%lu %d",&number,&n)==2)
    {
    
        printf("%d equivalent:",n);
        to_base_n(number,n);
        printf("\n");
    }
    system("Pause");

    return 0;
}

void to_base_n(unsigned long num,int n)
{
    
    int r;

    r=num%n;
    if (num>=n)
    {
    
        to_base_n(num/n,n);
    }        
    printf("%d",r);
}

9.11

#include<stdio.h>
#include<stdlib.h>

void Fibonacci(int length);

int main (void)
{
    
    int length;

    printf("Please enter a number (q to quit):");

    while (scanf("%d",&length)==1)
    {
    
        Fibonacci(length);
        printf("\n");
        printf("Please enter a number (q to quit):");

    }
    
    system("Pause");

    return 0;
}

void Fibonacci (int length)
{
    
    int len,x,y,temp;

    x=y=temp=1;

    for (len = 0;len<=length; len++)
    {
    
        printf("%d",x);
        printf(" ");
        temp=x+y;
        x=y;
        y=temp;
    }
    
}