1.修改程序清单10.7中的程序rain,使它不使用数组下标,而是使用指针进行计算(程序中仍然需要声明并初始化数组)
#include<stdio.h>
#define MONTHS 12
#define YEARS 5
int main()
{
const float rain[YEARS][MONTHS]={
{4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6},
{8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3},
{9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4},
{7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2},
{7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2}
};
int year,month;
float subtot,total;
const float *rainPtr;
rainPtr = rain[0];
printf("YEAR RAINFALL (inches)\n");
for(year = 0,total = 0; year < YEARS; year++)
{
for(month = 0,subtot = 0; month < MONTHS; month++)
{
subtot += *rainPtr;
rainPtr++;
}
printf("200%d %.1f\n",year,subtot);
total += subtot;
}
printf("\nThe yearly average is %.1f inches.\n",total/MONTHS);
printf("MONTHLY AVERAGES:\n\n");
printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct ");
printf(" Nov Dec\n");
rainPtr = rain[0]; //reset pointer
for(month = 0; month < MONTHS ; month++)
{
rainPtr = rainPtr + month;
for(year = 0,subtot = 0; year < YEARS ; year++)
{
subtot += *rainPtr;
rainPtr += MONTHS;
}
rainPtr = rain[0];
printf(" %.1f ",subtot/YEARS);
}
printf("\n");
return 0;
}
2.编写一个程序,初始化一个double数组,然后把数组内容复制到另外两个数组(3个数组都需要在主程序中声明)。制作第一份拷贝的函数使用数组符号。制作第二份拷贝的函数使用指针符号,并使用指针的增量操作。把目标数组名和要复制的元素数目做为参数传递给函数。也就是说,如果给定了下列声明,函数调用应该如下面所示:
#include<stdio.h>
#define SIZE 5
void copy_arr(double target1[],double source[],int n);
void copy_ptr(double *target2,double *source,int n);
void display(double *target,int n);
int main()
{
double source[SIZE]={
1.1,1.2,1,6.4,7.8
};
double target1[SIZE];
double target2[SIZE];
copy_arr(target1,source,SIZE);
copy_ptr(target2,source,SIZE);
display(target1,SIZE);
printf("\n");
display(target2,SIZE);
printf("\n");
return 0;
}
void copy_arr(double target1[],double source[],int n)
{
for(int i=0;i < n;i++)
{
target1[i] = source[i];
}
}
void copy_ptr(double *target2,double *source,int n)
{
for(int i = 0; i < n; i++)
{
//*target2 = *source;
//source++;
//target2++;
*target2++ = *source++;
}
}
void display(double *target,int n)
{
for(int i = 0 ; i < n ;i++)
{
printf("%2.2f ",*target++);
// target++;
}
}
3.编写一个函数,返回一个int数组中存储的最大数值,并在一个简单的程序中测试这个函数。
#include<stdio.h>
#define SIZE 5
int select_max(int *ptr,int n);
int main()
{
int array[SIZE] = {
1,2,3,4,5
};
int max;
max = select_max(array,SIZE);
printf("max is %d\n",max);
return 0;
}
int select_max(int *ptr,int n)
{
int max = *ptr;
for(int i = 0 ; i < SIZE ; i++)
{
if(max < *ptr)
max = *ptr;
ptr++;
}
return max;
}
4.编写一个函数,返回一个double数组中存储的最大数值的索引,并在一个简单程序中测试这个函数。
#include<stdio.h>
#define SIZE 5
int select_max(int *ptr,int n);
int main()
{
int array[SIZE] = {
1,2,3,4,5
};
int max_index;
max_index = select_max(array,SIZE);
printf("max index is %d\n",max_index);
return 0;
}
int select_max(int *ptr,int n)
{
int max = *ptr;
int max_index = 0;
for(int i = 0 ; i < SIZE ; i++)
{
if(max < *ptr)
{
max = *ptr;
max_index = i;
}
ptr++;
}
return max_index;
}
5.编写一个函数,返回一个double数组中最大的和最小的数之间的差值,并在一个简单的程序中测试这个函数。
#include<stdio.h>
#define SIZE 5
int D_value(int *ptr,int n);
int main()
{
int array[SIZE] = {
1,2,3,4,5
};
int value;
value = D_value(array,SIZE);
printf("max - min = %d\n",value);
return 0;
}
int D_value(int *ptr,int n)
{
int max = *ptr;
int min = *ptr;
for(int i = 0 ; i < SIZE ; i++)
{
if(max < *ptr )
{
max = *ptr;
}
if(min > *ptr)
min = *ptr;
ptr++;
}
return max-min;
}
6.编写一个程序,初始化一个二维double数组,并利用练习2中的任一函数来把这个数组复制到另一个二维数组(因为二维数组是数组的数组,所以可以使用处理一维数组的函数来复制数组的每个子数组)。
#include<stdio.h>
#define SIZE 6
void copy_ptr(double *target1,double *source,int n);
void display(double *target,int n);
int main()
{
double source[2][3]={
1.1,1.2,1,6.4,7.8
};
double target1[2][3];
copy_ptr(target1[0],source[0],SIZE);
display(target1[0],SIZE);
printf("\n");
printf("\n");
return 0;
}
void copy_ptr(double *target1,double *source,int n)
{
for(int i = 0; i < n; i++)
{
//*target2 = *source;
//source++;
//target2++;
*target1++ = *source++;
}
}
void display(double *target,int n)
{
for(int i = 0 ; i < n ;i++)
{
printf("%2.2f ",*target++);
// target++;
}
}
7.利用练习2中的复制函数,把—个包含7个元素的数组内第3到第5元素复制到一个包含3个元素的数组中。函数本身不需要修改,只需要选择合适的实际参数(实际参数不需要是数组名和数组大小,而只须是数组元素的地址和需要复制的元素数目)。
#include<stdio.h>
#define SIZE 5
#define TARGET_SIZE 3
void copy_ptr(double *target1,double *source,int n);
void display(double *target,int n);
int main()
{
double source[SIZE]={
1.1,1.2,1,6.4,7.8
};
double target1[TARGET_SIZE];
copy_ptr(target1,source+2,TARGET_SIZE);
display(target1,TARGET_SIZE);
printf("\n");
printf("\n");
return 0;
}
void copy_ptr(double *target1,double *source,int n)
{
for(int i = 0; i < n; i++)
{
*target1++ = *source++;
}
}
void display(double *target,int n)
{
for(int i = 0 ; i < n ;i++)
{
printf("%2.2f ",*target++);
// target++;
}
}
8.编写一个程序,初始化一个3x5的二维double数组,并利用一个基于变长数组的函数把该数组复制到另一个二维数组。还要编写。个基于变长数组的函数来显示两个数组的内容。这两个函数应该能够处理任意的NxM数组(如果没有可以支持变长数组的编译器,就使用传统C中处理Nx5数组的函数方法)。
#include<stdio.h>
#define ROW 3
#define COL 5
void copy_ptr(double *target1,double *source,int n);
void copy_arr(double target2[][COL],double source[][COL],int rows);
void display(double target[][COL],int rows);
int main()
{
double source[ROW][COL] = {
{1,1.2,4,5.6,7.8},
{1,1.2,4,5.6,7.8},
{1,1.2,4,5.6,7.8}
};
double target1[ROW][COL],target2[ROW][COL];
copy_ptr(target1[0],source[0],ROW*COL);
copy_arr(target2,source,ROW);
display(target1,ROW);
printf("\n");
display(target2,ROW);
printf("\n");
return 0;
}
void copy_ptr(double *target1,double *source,int n)
{
for(int i = 0; i < n; i++)
*target1++ = *source++;
}
void copy_arr(double target2[][COL],double source[][COL],int rows)
{
for(int i = 0 ; i < rows ; i++)
for(int j = 0; j < COL ; j++)
target2[i][j] = source[i][j];
}
void display(double target[][COL],int rows)
{
for(int i = 0 ; i < rows ; i++)
{
for(int j = 0; j < COL ; j++)
printf("%2.1f ",target[i][j]);
printf("\n");
}
}
9.编写一个函数,把两个数组内的相应元素相加,结果存储到第3个数组内。也就是说,如果数组l具有值2、4、5、8,数组2具有值1、0、4、6,则函数对数组3赋值为3、4、9、140函数的参数包括3个数组名和数组大小。并在一个简单的程序中测试这个函数。
#include<stdio.h>
#define SIZE 6
void sum(double *target1,double *target2,double *result,int n);
void display(double *target,int n);
int main()
{
double source1[SIZE]={
1.1,1.2,1,6.4,7.8
};
double source2[SIZE]={
1.1,1.2,1,6.4,7.8
};
double result[SIZE];
sum(source1,source2,result,SIZE);
display(result,SIZE);
printf("\n");
return 0;
}
void sum(double *target1,double *target2,double *result,int n)
{
for(int i = 0; i < n; i++)
{
result[i] = target1[i] + target2[i];
}
}
void display(double *target,int n)
{
for(int i = 0 ; i < n ;i++)
{
printf("%2.2f ",*target++);
// target++;
}
}
10.编写…个程序,声明一个3x5的数组并初始化,具体数值可以随意。程序打印出数值,然后数值翻1番,接着再次打印出新值。编写一个函数来显示数组的内容,再编写另一个函数执行翻倍功能。数组名和数组行数作为参数由程序传递给函数
#include<stdio.h>
#define ROW 3
#define COL 5
void double_arr(double target[][COL],int rows); //arrry*2
void display(double source[][COL],int rows);
int main()
{
double source[ROW][COL] = {
{1,1.2,4,5.6,7.8},
{1,1.2,4,5.6,7.8},
{1,1.2,4,5.6,7.8}
};
display(source,ROW);
double_arr(source,ROW);
printf("\n");
display(source,ROW);
printf("\n");
return 0;
}
void double_arr(double source[][COL],int rows)
{
for(int i = 0 ; i < rows ; i++)
for(int j = 0; j < COL ; j++)
source[i][j] = source[i][j] * 2;
}
void display(double source[][COL],int rows)
{
for(int i = 0 ; i < rows ; i++)
{
for(int j = 0; j < COL ; j++)
printf("%2.1f ",source[i][j]);
printf("\n");
}
}
11.重写程序清单10.7的程序rain,main()中的主要功能改为由函数来执行。
#include <stdio.h>
#define MONTHS 12 // number of months in a year
#define YEARS 5 // number of years of data
void every_total(const float source[][MONTHS],int years); //rainfull of every year and total rainfull
void average_month(const float source[][MONTHS],int years);//average rainfull of every month
int main(void)
{
// initializing rainfall data for 2000 - 2004
const float rain[YEARS][MONTHS] =
{
{4.3,4.3,4.3,3.0,2.0,1.2,0.2,0.2,0.4,2.4,3.5,6.6},
{8.5,8.2,1.2,1.6,2.4,0.0,5.2,0.9,0.3,0.9,1.4,7.3},
{9.1,8.5,6.7,4.3,2.1,0.8,0.2,0.2,1.1,2.3,6.1,8.4},
{7.2,9.9,8.4,3.3,1.2,0.8,0.4,0.0,0.6,1.7,4.3,6.2},
{7.6,5.6,3.8,2.8,3.8,0.2,0.0,0.0,0.0,1.3,2.6,5.2}
};
every_total(rain,YEARS);
average_month(rain,YEARS);
printf("\n");
return 0;
}
void every_total(const float source[][MONTHS],int years)
{
printf("YEAR RAINFULL(inches)\n");
float subtotal,total;
subtotal = 0;
total = 0;
for(int i = 0; i < years ; i++)
{
for(int j = 0; j < MONTHS; j++)
{
subtotal += source[i][j];
}
printf("200%d %2.1f\n",i,subtotal);
total += subtotal;
subtotal = 0 ; //reset subtotal to 0
}
printf("The yearly average is %2.1f inches\n",total/YEARS);
}
void average_month(const float source[][MONTHS],int years)
{
float sub = 0;
printf("MONTHLY AVERAGES:\n\n");
printf(" Jan Feb Mar Apr May Jun Jul Aug Sep Oct ");
printf(" Nov Dec\n");
for(int i = 0; i < MONTHS ; i++)
{
for(int j = 0; j < years; j++)
{
sub += source[j][i];
}
printf(" %2.1f ",sub);
sub = 0; //reset sub= 0
}
}
12.编写…个程序,提示用户输入3个数集,每个数集包括5个double值。程序应当实现下列所有功能:
a.把输入信息存储到一个3x5的数组中
b.计算出每个数集(包含5个数值)的平均值
c.计算所有数值的平均数
d.找出这15个数中的最大值.
e.打印出结果
每个任务需要用一个单独的函数来实现(使用传统C处理数组的方法)。对于任务b,需要编写计算并返回一维数组平均值的函数,循环3次调用该函数来实现任务b。对于其他任务,函数应当把整个数组做为参数,并且完成任务c和d的函数应该向它的调用函数返回答案。
#include<stdio.h>
#define ROWS 3
#define COLS 5
void input_arrays(double source[][COLS],int rows); //input arrays
void average_array(double source[][COLS],double averages[],int rows); //compute the average of every arrays
void average_total(double *source,int rows); //compute average of all arrays
void output_arrays(double source[][COLS],int rows); //output arrays
double max(double source[][COLS],int rows);// find the max one
int main(void)
{
double source[ROWS][COLS];
double averages[ROWS];
input_arrays(source,ROWS); //input array
printf("the array you input is:\n");
output_arrays(source,ROWS); //output array
average_array(source,averages,ROWS); //compute the average value of each array
printf("\n the average value of every array is :\n");
for(int i = 0;i < ROWS ;i++ )
{
printf("%.2f ",averages[i]);
}
printf("\n the max one is %.2f\n",max(source,ROWS));
return 0;
}
void input_arrays(double source[][COLS],int rows) //input arrays
{
printf("please input 3 arrays, 5 counts for each array:\n ");
for(int i = 0 ; i < rows ; i++)
for(int j = 0; j < COLS ; j++)
scanf("%lf",&source[i][j]);
}
//compute the average of every arrays
void average_array(double source[][COLS],double averages[],int rows)
{
double subtotal = 0;
for(int i = 0 ; i < rows; i++)
{
for(int j = 0 ; j < COLS; j++)
{
subtotal += source[i][j];
}
averages[i] = subtotal/COLS;
subtotal = 0; //reset subtotal = 0
}
}
//output arrays
void output_arrays(double source[][COLS],int rows)
{
for(int i = 0 ; i < rows ; i++)
{
for(int j = 0; j < COLS ; j++)
printf("%.2lf ",source[i][j]);
printf("\n");
}
}
double max(double source[][COLS],int rows)
{
double max = source[0][0];
for(int i = 0 ; i < rows ; i++)
{
for(int j = 0; j < COLS ; j++)
if(source[i][j] > max)
max = source[i][j];
}
return max;
}
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