Question

c语言如何返回一个数组？

extend()函数返回数组amounts怎么改？

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

double extend(double[],double[]);

int main(){
double price[] = {10.62,14.89,13.21,16.55,18.62,9.47,6.58,18.32,12.15,3.98};
double quantity[] = {4,8.5,6,8.35,9,15.3,3,5.4,2.9,4.8};
double amount[10];
int i;

extend(price,quantity);

for (i = 0; i < 10; i++){
printf("%lf\n", amount[i]);
}

printf("\n");
return 0;
}

double extend(double prices[], double quantities[]){
int i;
double amounts[10];

for (i = 0; i < 10; i++){
amounts[i] = prices[i] * quantities[i];
}

return amounts;
}

Answer 1

只能返回一个数，数组不能返回，以数组为函数参数传给形参时，由于是数组名传递（地址传递），实参和形参共用一段内存，对形参更改时实参的值也会改变，所以不需要返回值

Answer 2

只能返回一个数，数组不能返回，以数组为函数参数传给形参时，由于是数组名传递（地址传递），实参和形参共用一段内存，对形参更改时实参的值也会改变，所以不需要返回值

Answer 3

return amounts;
你返回的是地址，所以函数类型应该是指针型的才能返回。
即 * extend

Answer 4

double extend(double prices[], double quantities[]){
int i;
double amounts[10];

for (i = 0; i < 10; i++){
amounts[i] = prices[i] * quantities[i];
}

return amounts; //栈中局部变量，返回后其内存为垃圾值
}
改成：

double *extend(double[],double[]);

int main(){
double price[] = {10.62,14.89,13.21,16.55,18.62,9.47,6.58,18.32,12.15,3.98};
double quantity[] = {4,8.5,6,8.35,9,15.3,3,5.4,2.9,4.8};
//double amount[10];
double *amount;
int i;

amount = extend(price,quantity);

for (i = 0; i < 10; i++){
printf("%lf\n", amount[i]);
}

delete[] amount; //释放内存

printf("\n");
return 0;
}

double *extend(double prices[], double quantities[]){
int i;
//double amounts[10];
double *amounts = new double[10];
for (i = 0; i < 10; i++){
amounts[i] = prices[i] * quantities[i];
}

return amounts; //可以返回指针
}}

Answer 5

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

double extend(double[],double[],double *p);

int main()
{
double price[] = {10.62,14.89,13.21,16.55,18.62,9.47,6.58,18.32,12.15,3.98};
double quantity[] = {4,8.5,6,8.35,9,15.3,3,5.4,2.9,4.8};
double amount[10];
int i;

int j = extend(price,quantity, amount);

for (i = 0; i < j; i++)
{
printf("%lf\n", amount[i]);
}

printf("\n");
return 0;
}
//传入要返回的数组名，函数返回数组的大小
int extend(double prices[], double quantities[]，double *p)
{
int i;

for (i = 0; i < 10; i++)
{
*（p+i）= prices[i] * quantities[i];
}

return i;
}