c primer plus 习题答案(3)

p281.2

#include<stdio.h>
#include<stdlib.h>
#define SIZE 5
void copy_arr(double ar[], double pr[],int n);
void copy_ptr(double ar[], double pr[], int n);

int main(void)    
{
    double source[5]={1.1, 2.2, 3.3, 4.4, 5.5};
    double target1[5];
    double target2[5];

    copy_arr(source, target1, 5);
    copy_ptr(source, target2, 5);
    
    system("pause");
    return 0;
}

void copy_arr(double ar[], double pr[],int n)
{
    int i;
    for(i=0; i<n; i++)
    {
        pr[i]=ar[i];
        printf(" %lf", pr[i]);
    }
    printf("
");
}

void copy_ptr(double ar[], double pr[], int n)
{
    int i;
    for(i=0; i<5; i++)
    {
        *(pr+i)=*(ar+i);
        printf(" %lf", pr[i]);
    }
    printf("
");
}

p281.4

#include<stdio.h>
#include<stdlib.h>
#define n 5
int compare(double [], int);


int main(void)    
{
    double ar[]={2.1, 3.1, 4.1, 3.2, 6.2};
    printf("the biggest number index is %d", compare(ar, n));

    system("pause");
    return 0;
}

int compare(double ar[], int num){
    int i, max=ar[0], j=0;

    for(i=1; i<num; i++){
        if(max<ar[i]){
            max=ar[i];
            j=i;
        }
    }
    return j;
}

p281.5

#includestdio.h
#includestdlib.h
#define n 5
double d_value(double [], int);


int main(void)    
{
    double ar[]={2.1, 3.1, 4.1, 3.2, 6.2};
    printf(the difference value is %lf, d_value(ar, n));

    system(pause);
    return 0;
}

double d_value(double ar[], int num){
    int i; 
    double max=ar[0], min=ar[0];

    for(i=1; inum; i++){
        if(maxar[i])
            max=ar[i];
    }

    for(i=1; inum; i++){
        if(minar[i])
            min=ar[i];
    }
    return max-min;
}

p281.6

A方案

#include<stdio.h>
#include<stdlib.h>
#define COLS 2
#define ROWS 3
void copy_ptr(double source[ROWS][COLS], double target[ROWS][COLS]);

int main(void)    
{
    int i, j;
    double source[ROWS][COLS]={{2.1, 1.2}, {3.1, 2.3}, {4.2, 3.5}}; 
    double target[ROWS][COLS]={0};
    
    for(i=0; i<ROWS; i++)
        for(j=0; j<COLS; j++)
    printf(" %lf", source[i][j]);
    printf("
");
    copy_ptr(source, target);

    system("pause");
    return 0;
}

void copy_ptr(double source[ROWS][COLS], double target[ROWS][COLS])
{
    int i, j;

    for(i=0; i<ROWS; i++)
        for(j=0; j<COLS; j++){
            target[i][j]=source[i][j];
            printf(" %lf", target[i][j]);
        }
    printf("
");
}

B方案

#include<stdio.h>
#include<stdlib.h>
#define COLS 2
#define ROWS 3
void copy_ptr(double source[][COLS], double target[][COLS], int);
void copy_ar(double *a1, double *a2, int n);

int main(void)    
{
    int i, j;
    double source[ROWS][COLS]={{2.1, 1.2}, {3.1, 2.3}, {4.2, 3.5}}; 
    double target[ROWS][COLS]={0};

    copy_ptr(source, target, ROWS);
    for(i=0; i<ROWS; i++)
        for(j=0; j<COLS; j++)
            printf(" %lf", target[i][j]);
    
    system("pause");
    return 0;
}

void copy_ptr(double source[ROWS][COLS], double target[ROWS][COLS], int n)
{
    int i;

    for(i=0; i<n; i++){
        copy_ar(source[i], target[i], COLS);
    }    
}

void copy_ar(double *a1, double *a2, int n)
{
    int i;

    for(i=0; i<n; i++)
        *(a2+i)=*(a1+i);
}

p281.10

#include<stdio.h>
#include<stdlib.h>
#define COLS 5
void dbl(int [][COLS], int [][COLS], int);
void typeout(int[][COLS], int);

int main(void)
{
    int source[3][5]={{1, 2, 7, 4, 1}, {2, 3, 8, 5, 4}, {5, 6, 8, 3, 2}};
    int ar[6][COLS]={0}, rows=3;

    dbl(source, ar, rows);
    typeout(source, rows);
    typeout(ar, rows);

    system("pause");
    return 0;
}

void dbl(int a1[][COLS], int a2[][COLS], int rows)
{
    int i, j;

    for(i=0; i<rows; i++)
        for(j=0; j<COLS; j++)
            (*(a2+i))[j]=2*(*(a1+i))[j];
}

void typeout(int b1[][COLS], int rows)
{
    int i, j;
    for(i=0; i<rows; i++){
        for(j=0; j<COLS; j++)
            printf("%d", b1[i][j]);
    printf("
");
    }
}

p281.12

#include<stdio.h>
#include<stdlib.h>
#define COLS 3
void collect(int [][COLS], int);
void mean(int [][COLS], int);
void tot_mean(int [][COLS], int);
void max(int[][COLS], int);

int main(void)
{
    int rows=3;
    int num[3][3];
    collect(num, rows);
    mean(num, rows);
    tot_mean(num, rows);
    max(num, rows);

    system("pause");
    return 0;
}

void collect(int num[][COLS], int rows)
{
    int i, j;
    for(i=0; i<rows; i++){
        for(j=0; j<COLS; j++){
            scanf("%d", &num[i][j]);
            printf("%5d", num[i][j]);
        }
        printf("
");
    }
}

void mean(int num[][COLS], int rows)
{
    int i, j, sum;
    double mean;

    for(i=0; i<rows; i++){
        sum=0;
        for(j=0; j<COLS; j++)
            sum+=num[i][j];
        mean=sum/5.0;
        printf("the average is:");
        printf("%.2
", mean);
    }
}

void tot_mean(int num[][COLS], int rows)
{
    int i, j, sum=0;
    double mean;

    for(i=0; i<rows; i++)
        for(j=0; j<COLS; j++)
            sum+=num[i][j];
    mean=sum/15.0;
    printf("the tot_mean is:");
    printf("%.2lf
", mean);
}

void max(int num[][COLS], int rows)
{
    int i, j, max=num[0][0];

    for(i=0; i<rows; i++)
        for(j=0; j<COLS; j++)
            if(max<num[i][j])
                max=num[i][j];
    printf("the largest number is %d
", max);
}