c primer plus 9编程练习

复习题 9

#include <stdio.h>

void show_menu(void);

int getchoice(int low, int high);

int main(void)
{
    int res;
    show_menu();
    
    while((res = getchoice(1,4)) != 4)
    {
        printf("I would like to choose %d. 

", res);
        show_menu();
    }
    
}

void show_menu(void)
{
    printf("Please choose one of the following: 
");
    printf("1) copy files            2) move files
");
    printf("3) remove files          4) quit.
");
    printf("Enter the number of your choice: ");
}

int getchoice(int low, int high)
{
    int choice;
    int status;
    
    while((status = scanf("%d", &choice)) == 1 && ( choice < low || choice > high ))
    {
        printf("
 You can only intput %d - %d.
", low, high);
        show_menu();
    }
    
    if(status != 1)
        choice = 4;
        
    return choice;
}

1、

#include <stdio.h>

double smaller(double x, double y);

int main(void)
{
    double a = 3.0, b = 1.0;
    
    printf("the smaller is: %.2f.
", smaller(a, b));
    
    return 0;
}

double smaller(double x, double y)
{
    double smaller;
    
    if (x < y)
        smaller = x;
    else
        smaller = y;
        
    return smaller;
}

#include <stdio.h>

double smaller(double x, double y);

int main(void)
{
    double a = 3.0, b = 1.0;
    
    printf("the smaller is: %.2f.
", smaller(a, b));
    
    return 0;
}

double smaller(double x, double y)
{
    return x < y ? x : y;
}

2、

#include <stdio.h>

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

int main(void)
{
    char ch = '!';
    int a = 5, b = 3;
    
    chline(ch, a, b);
    
    return 0;
}

void chline(char ch, int i, int j)
{
    int x, y;
    
    for(x = 1; x <= j; x++)
    {
        for(y = 1; y <= i; y++)
            putchar(ch);
        putchar('
');
    }
}

3、

#include <stdio.h>

void putstr(char ch, int x, int y);

int main(void)
{
    char ch;
    int rows, cols;
    printf("please input the char you want to put: ");
    scanf("%c", &ch);
    printf("please input the cols: ");
    scanf("%d", &cols);
    printf("please input the rows: ");
    scanf("%d", &rows);
    
    putstr(ch, cols, rows);
    
    return 0;
}

void putstr(char ch, int x, int y)
{
    int i, j;
    
    for(i = 1; i <= y; i++)
    {
        for(j = 1; j <= x; j++)
        {
            putchar(ch);
        }
        putchar('
');
    }
}

4、

#include <stdio.h>

double harmean(double x, double y);

int main(void)
{
    double a, b;
    printf("please input two double num.
");
    printf("a = ");
    scanf("%lf", &a);
    printf("b = ");
    scanf("%lf", &b);
    
    printf("the harmean is : %.2f.
", harmean(a, b));
    
    return 0; 
}

double harmean(double x, double y)
{
    double temp1;
    
    temp1 = 1/((1/x + 1/y)/2);
    
    return temp1;
}

#include <stdio.h>

double harmean(double x, double y);

int main(void)
{
    double a, b;
    printf("please input two double num.
");
    printf("a = ");
    scanf("%lf", &a);
    printf("b = ");
    scanf("%lf", &b);
    
    printf("the harmean is : %.2f.
", harmean(a, b));
    
    return 0; 
}

double harmean(double x, double y)
{
    double temp1;
    
    temp1 = 2/(1/x + 1/y);
    
    return temp1;
}

5、

#include <stdio.h>

void larger(double * x, double * y);

int main(void)
{
    double a, b;
    printf("please input double a: ");
    scanf("%lf", &a);
    printf("please input double b: ");
    scanf("%lf", &b);
    
    larger(&a, &b);
    
    printf("a: %.2f.
", a);
    printf("b: %.2f.
", b);
    
    return 0;
}

void larger(double * x, double * y)
{
    if(*x > *y)
        *y = *x;
    else
        *x = *y;
}

6、

#include <stdio.h>

void sort(double * x, double * y, double * z);

int main(void)
{
    double a, b, c;
    printf("please input double a: "); scanf("%lf", &a);
    printf("please input double b: "); scanf("%lf", &b);
    printf("please input double c: "); scanf("%lf", &c);
    
    sort(&a, &b, &c);
    
    printf("a: %.2f.
", a);
    printf("b: %.2f.
", b);
    printf("c: %.2f.
", c);
    
    return 0;
}

void sort(double * x, double * y, double * z)
{
    double min, med, max;
    
    min = *x;
    min = min < *y ? min : *y;
    min = min < *z ? min : *z;
    
    max = *x;
    max = max > *y ? max : *y;
    max = max > *z ? max : *z;
    
    if(*x > min && *x < max)
        med = *x;
    if(*y > min && *y < max)
        med = *y;
    if(*z > min && *z < max)
        med = *z;
    
    *x = min;
    *y = med;
    *z = max;
    
}

#include <stdio.h>

void sort(double * x, double * y, double * z);

int main(void)
{
    double a, b, c;
    printf("please input double a: "); scanf("%lf", &a);
    printf("please input double b: "); scanf("%lf", &b);
    printf("please input double c: "); scanf("%lf", &c);
    
    sort(&a, &b, &c);
    
    printf("a: %.2f.
", a);
    printf("b: %.2f.
", b);
    printf("c: %.2f.
", c);
    
    return 0;
}

void sort(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;
    }
    
}

7、

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

void report(void);

int main(void)
{
    printf("please input some char: ");
    report(); 
    
    return 0;
}

void report(void)
{
    char ch;
    
    while((ch = getchar()) != EOF)
    {
        if(isalpha(ch))
        {
            if(isupper(ch))
            {
                putchar(ch);
                putchar(' ');
                printf("%d
", 26 - ('Z' - ch));
            }
            else
            {
                putchar(ch);
                putchar(' ');
                printf("%d
", 26 - ('z' - ch));
            }
        }
        else
            {
                putchar(ch);
                putchar(' ');
                printf("%d
", -1);
            }
            
    }
}

#include <stdio.h>

void get_char_pos(void);

int position(char ch);

int main(void)
{
    get_char_pos();
}

void get_char_pos(void)
{
    char ch;
    printf("Enter the chars(ended by EOF, now enter):" );
    while((ch = getchar()) != EOF)
    {    
    if(ch == '
')
        continue;
    if(position(ch) != -1)
    {
        printf("The char %c's position in alphabet is %d.
", ch, position(ch));
    }
    else
        printf("%c is not a alphabet.
", ch);
    }
}

int position(char ch)
{
    if(ch >= 'A' && ch <= 'Z')
        return ch - 'A' + 1;
    if(ch >= 'a' && ch <= 'z')
        return ch - 'a' + 1;
    return -1;
}

#include <stdio.h>

void getch(void);

int show(char ch);

int main(void)
{
    getch();
    
    return 0;
} 

void getch(void)
{
    char ch;
    
    printf("please input str: 
");
    
    while((ch = getchar())  != EOF)
    {
        if(ch == '
')
            continue;
        if(show(ch) != -1)
        {
            printf("%c is %d.
", ch, show(ch));
        }
        else
        {
            printf("%c is not alpha.
");
        }
    }
}

int show(char ch)
{
    if(ch >= 'A' && ch <= 'Z')
        return ch - 'A' + 1;
    if(ch >= 'a' && ch <= 'z')
        return ch - 'a' + 1;
    return -1;
}

8、

#include <stdio.h>

double power(double x, int y);

int main(void)
{
    double a;
    int b;
    double result;
    printf("please input a pair number, q to quit: 
");
    
    while((scanf("%lf %d", &a, &b)) == 2)
    {
        result = power(a, b);
        printf("the result is: %.2f.
", result);
        printf("please input another pair number: 
"); 
            
    }
    printf("hope you enjoy the power trip -- bye.
");
    
    return 0;
} 

double power(double x, int y)
{
    int i;
    double power = 1.0;
    
    if(x == 0)
    {
        if(y != 0)
            power = 0;
        else
            {
                printf("0 power 0 not defined, regard as 1.
");
                power = 1;
            }
    }
    
    else
    {
        if(y > 0)
        {
            for(i = 1; i <= y; i++)
            {
                power *= x;
            }
        }
        else if(y < 0)
        {
            for(i = 1; i <= -y; i++)
            {
                power *= x;
            }
            power = 1/power;
        }
        else
        {
            power = 1;
        }
    }
    return power;
}

9、

#include <stdio.h>

double power(double n, int p);

int main(void)
{
    double x, xpow;
    int exp;
    
    printf("Enter a number and the integer power:(q to quit).
");
    
    while(scanf("%lf %d", &x, &exp) == 2)
    {
        xpow = power(x, exp);
        printf("%.3g to the power %d is %.5g
", x, exp, xpow);
        printf("Enter the next pair of number or q to quit.
");
    }
    printf("Hope you enjoy this power trip -- bye!
");
    
    return 0;
}

double power(double n, int p)
{
    double pow = 1;
    int i;
    
    if(n == 0 && p == 0)
    {
        printf("The %g to the power %c is not define, return 1!
", n, p);
        return 1;
    }
    if(n == 0)
        return 0;
    if(p == 0)
        return 1;
    if(p > 0)
    {
        return n * power(n, p-1);
    }
    else
    {
        return power(n, p+1)/n;
    }
}

10、

#include <stdio.h>

unsigned long get_long(void);

int get_unit(void);

void to_binary(unsigned long x, int y);

int main(void)
{
    unsigned long a;
    int b;
    char ch;
    
    do
    {    
        
        a = get_long();
        
        
        b = get_unit();
        
        to_binary(a, b);
        putchar('
');
        
        while(getchar() != '
')
            continue;
        
        printf("choose to continue or exit q to quit other to continue: ");
        while((ch = getchar()) == 'q')
            break;
        
    }
    while(ch != 'q');
    
    
    return 0;
} 

void to_binary(unsigned long x, int y)
{
    int temp;
    
    temp = x % y;
    if(x >= y)
        to_binary(x/y, y);
    printf("%d",temp);
}

unsigned long get_long(void)
{
    unsigned temp;
    
    printf("please input an unsigned long: ");
    
    while(scanf("%lu", &temp) != 1)
    {
        scanf("%*s");
        printf("please input an unsigned long num: ");
    }
    
    return temp;
}

int get_unit(void)
{
    int temp;
    int status;
    
    printf("please input an integer: ");
    
    while((status = scanf("%d", &temp)) != 1 || (temp < 2 || temp > 10))
    {
        if(status != 1)
        {
            scanf("%*s");
            printf("please input num: ");
        }    
        else
        {
            printf("please input 2-10 number: ");
        }
    }
    return temp;
}

#include <stdio.h>

void to_base_n(unsigned long n, unsigned short int t);

int main(void)
{
    unsigned long number;
    unsigned short int target;
    
    printf("please enter the integer and N for natation(q to quit): ");
    
    while(scanf("%lu %hu", &number, &target) == 2)
    {
        if(target < 2 || target > 10)
        {
            printf("please input N between 2 and 10!
");
            printf("Enter the integer and N for notation(q to quit): ");
            continue;
        }
        printf("conber %lu to %hu notation is: ", number, target);
        to_base_n(number, target);
        putchar('
');
        printf("Enter the integer and N for notation(q to quit): ");
    }
    return 0;
}

void to_base_n(unsigned long n, unsigned short t)
{
    int r;
    r = n % t;
    if(n >= t)
        to_base_n(n/t, t);
    printf("%d", r);
}

11、

#include <stdio.h>

void fibonacci(int x);

int main(void)
{
    int end;
    
    printf("please input the end: ");
    scanf("%d", &end);
    
    fibonacci(end);
        
} 


void fibonacci(int x)
{
    int i;
    int temp1 = 1;
    int temp2 = 1;
    int temp3 = 0;
    
    printf("%d ", 1);
    printf("%d ", 1);
    for(i = 1; 1 ;i++)
    {
        temp3 = temp1 + temp2;
        if(temp3 > x)
            break;
        printf("%d ", temp3);
        temp1 = temp2;
        temp2 = temp3; 
        
    }
}

#include <stdio.h>

void fibonacci(int x);

int main(void)
{
    int end;
    int status;
    printf("please input the end (q to quit): ");
    
    while(scanf("%d", &end) == 1)
    {
        fibonacci(end);
        printf("please input the end (q to quit): ");
    }
    
    return 0;    
} 

void fibonacci(int x)
{
    int i;
    int temp1 = 1;
    int temp2 = 1;
    int temp3 = 0;
    
    printf("%d ", 1);
    printf("%d ", 1);
    for(i = 1; 1 ;i++)
    {
        temp3 = temp1 + temp2;
        if(temp3 > x)
            break;
        printf("%d ", temp3);
        temp1 = temp2;
        temp2 = temp3; 
        
    }
    putchar('
');
}

#include <stdio.h>

void fibonacci(int x);

int main(void)
{
    int n;
    
    printf("please input an unsigned short int(q to quit): ");
    while(scanf("%uh",&n) == 1)
    {
        if(n < 1)
        {
            printf("please input positive num: ");
            continue;
        }
        fibonacci(n);
        printf("please input an unsigned short int(q to quit): ");
    }    
　　return 0;
} 

void fibonacci(int x)
{
    int f1 = 1, f2 = 1;
    int i, temp;
    
    for(i = 1; i <= x; i++)
    {
        printf("%d ", f1);
        temp = f1 + f2;
        f1 = f2;
        f2 = temp;
    }
    putchar('
');
}