c prime plus 第六版第六章课后编程答案

6-1

#include <stdio.h>
int main(void)
{
    int i;
    char a[25];
    for (i = 0; i <=25; i++)
    {
         a[i]='a'+i;
         printf("%c\n",a[i]);
    }
    return 0;
}

6-2

#include <stdio.h>
int main(void)
{
    int i,j;
    for (i = 1; i <=5; i++)
     {  
        for (j = 1; j<=i; j++)
        printf("%c",'$');
        printf("\n");
     }     
    return 0;
}

6-3

#include <stdio.h>
int main(void)
{
    int i,j;
    for (i = 0; i<=5; i++)
     {  
        for (j = 70; j>=70-i; j--)
        printf("%c",j);
        printf("\n");
     }     
    return 0;
}

6-4

#include <stdio.h>
int main(void)
{
    char ch = 'A';
    int i,j;
    for(i=1; i <= 6; i++)
    {
        for( j = 1; j <= i; j++)
        {
            printf("%c", ch++);
        }
        printf("\n");
    }

    return 0;
}

6-5

#include <stdio.h>

int main(void)
{
    char ch;
    int i,j;
    scanf("%c", &ch);

    int length = ch - 'A';
    for(i=0; i <= length; i++)
    {
        char t = 'A' - 1;
        for(j=0; j < length - i; j++)
        {
            printf(" ");
        }
        for(j= 0; j <= i; j++)
        {
            printf("%c", ++t);
        }
        for( j=0; j < i; j++)
        {
            printf("%c", --t);
        }
        printf("\n");
    }

    return 0;
}

6-6

#include <stdio.h>
int main(void)
{
    int upper, lower,i;
    printf("Please input the upper limits: ");
    scanf("%d", &upper);
    printf("Please input the lower limits: ");
    scanf("%d", &lower);

    printf("%s\t%s\t%s\t\n", "number", "square", "cube");
    for ( i = lower; i <= upper; i++)
    {
        printf("%d\t%d\t%d\n", i, i * i, i * i * i);
    }
    printf("Done.\n");

    return 0;
}

6-7

#include <stdio.h>
#include <string.h>
int main(void)
{
   char a[40];
   int i,j;
   scanf("%s",a);
   i = strlen(a);
   for(j = i;j > 0;j--)
   {
        printf("%c",a[j-1]);
   }   
    return 0;
}

6-8

#include <stdio.h>
int main(void)
{
    float f1,f2,f;
    while (scanf("%f%f",&f1,&f2) == 2)
    {
        f =  (f1 - f2) / (f1 * f2);
        printf("%f\n",f);
    }
    printf("quit\n");
    return 0;
}

6-9

#include <stdio.h>
void function(float f1,float f2);
int main(void)
{
    float a,b;
    while (scanf("%f%f",&a,&b) == 2)
    {
        function(a,b);
    }
    printf("quit\n");
    return 0;
}


void function(float f1,float f2)
{
    float f;
    f =  (f1 - f2) / (f1 * f2);
    printf("%f\n",f);
}

6-10

#include <stdio.h>
int main(void)
{
    int high,low;
    int i;
    int sum = 0;
    while ((scanf("%d %d", &low, &high) == 2) && (high > low))
    {
        for(i = low; i <= high; i++)
        {
            sum = sum + i * i;
        }
        printf("%d\n",sum);
    }
    printf("done\n");
    return 0;
}

6-11

#include <stdio.h>
int main(void)
{
    int a[8];
    int i;
    for(i = 0;i < 8;i++)
    {
        scanf("%d",&a[i]);    
    }
    
    for(i = 7;i >= 0;i--)
    {
       printf("%d",a[i]);
    }
    return 0;
}

6-12

#include <stdio.h>
#include <math.h>
int main(void)
{
      int i,n;
      double sum1 =0.0;
      double sum2 =0.0;
      scanf("%d",&n);
      for(i = 1;i <= n;i++)
      {
         sum1 = sum1 + 1 / i;
         sum2 = sum2 + pow(-1,i-1)* 1 / i;
      }
         printf("%g %g\n",sum1,sum2);
         return 0;
}

6-13

#include <stdio.h>

int main(void)
{
    int a[8], val = 2;
    int i;

    for (i = 0; i < 8; i++)
    {
        a[i] = val, val *= 2;
    }
    int j = 0;
    printf("Here are the results for array:\n");
    do
    {
        printf("%d ", a[j++]);
    } while (j < 8);
    printf("\nDone.\n");

    return 0;
}

6-14

#include <stdio.h>
#define N 8

int main(void)
{
    double a[N], b[N];
    int i;

    printf("Please enter %d numbers:\n", N);
    for ( i = 0; i < N; i++)
    {
        scanf("%lf", &a[i]);
    }
    b[0] = a[0];
    for ( i = 1; i < N; i++)
    {
        b[i] = a[i] + b[i - 1];
    }
    printf("Here are the results for array a:\n");
    for ( i = 0; i < N; i++)
    {
        printf("%-3g", a[i]);
    }
    printf("\nHere are the results for array b:\n");
    for ( i = 0; i < N; i++)
    {
        printf("%-3g", b[i]);
    }
    printf("\nDone.\n");

    return 0;
}

6-15

#include <stdio.h>
#define LEN 255

int main(void)
{
    int i = 0;
    char s[LEN];

    printf("Please enter a string:\n");
    while (scanf("%c", &s[i]) && i + 1 < LEN && s[i] != '\n')
    {
        ++i;
    }
    printf("Reversing print the string is:\n");
    for (i--; i >= 0; i--)
    {
        printf("%c", s[i]);
    }
    printf("\nDone.\n");

    return 0;
}

6-16

#include <stdio.h>

int main(void)
{
    int years = 0;
    double daphne = 100.0, deirdre = 100.0;

    while (deirdre <= daphne)
    {
        daphne += 0.10 * 100.0;
        deirdre += 0.05 * deirdre;
        ++years;
    }
    printf("Investment values after %d years:\n", years);
    printf("Daphne: $%.2f\n", daphne);
    printf("Deirdre: $%.2f\n", deirdre);
    printf("Deirdre(invest) > Daphne(invest)\n");

    return 0;
}

6-17

#include <stdio.h>

int main(void)
{
    int years = 0;
    double chuckie = 100.0;
    
    while (chuckie > 9)
    {
        ++years, chuckie += chuckie * 0.08, chuckie -= 10;
        printf("After %d years remains $%g.\n", years, chuckie);
    }
    printf("After %d years:\n", years + 1);
    printf("Chuckie has taken all of the money!\n");

    return 0;
}

6-18

#include <stdio.h>
int main(void)
{
    int i = 1;
    int friends = 5;

    while (friends < 150)
    {
        printf("At %d weeks, Rabnud has", i);
        friends = 2 * (friends - i++);
        printf("%4d friends.\n", friends);
    }
    printf("At %d weeks, over Dunbar's number(150).\n", i);

    return 0;
}