“不应忽略的无效值”尝试对数组进行排序时

Question

I'm new to programming and trying to program a sensor. I'm sorting the array that I plot the input from the sensor into. But I'm running into a problem when sorting it, it gives me this error:

exit status 1
void value not ignored as it ought to be"

Here's my code:

#include <ArduinoSort.h>

int a[10];
int b[10];
int sensor1 = A0;
int sensor2 = A1;
int display1;
int display2;
int sort[10];

void setup() {
    // put your setup code here, to run once:
    Serial.begin(9600);
}

void loop() {
    // put your main code here, to run repeatedly:
    delay(100);
    Serial.print("Sensor 1: [");

    for (int i = 0; i < 11; i++) {
        display1 = analogRead(sensor1);
        a[i] = display1;
        sort[i] = sortArray(a, 10);
        if (i < 10) {
            Serial.print(String(sort[i]) + ",");
        } else {
            Serial.print(String(sort[i]));
        }
    }

    Serial.print("]");
    Serial.println();

    Serial.print("Sensor 2: [");
    for (int i = 0; i < 11; i++) {
        display2 = analogRead(sensor2);
        b[i] = display2;
        if (i < 10) {
            Serial.print(String(b[i]) + ",");
        } else {
            Serial.print(String(b[i]));
        }

    }
    Serial.print("]");
    Serial.println();
    Serial.println();

    //String hej = "Sensor 1"+ String(display1);
    //Serial.println(hej);
}

and, on this line I get the error:

sort[i] = sortArray(a,10);

Answer 1

The sortArray() function returns nothing ie void .

It sorts the passed array in-place so you need to call it like this:

sortArray(a, 10); // no return value assignment

---

As pointed out by Ben Voigt , you have not initialized a properly so you need to first collect all the values and then sort it after the loop.

Here's your loop (after correction of sortArray after loop):

for (int i = 0; i < 11; i++) {  // 0-10 i.e. 11 iterations
    a[i] = analogRead(sensor1); // read values in the array
    // ...
}

sortArray(a, 10); // sort after the loop

---

Another problem is that your loop's condition is i < 11 which means the iterations from 0 to 10 ie 11 iterations. But, the arrays you're using are of size 10 ie 0 to 9 locations as C++ arrays are ZERO-based. So, this is causing out-of-bounds access resulting in Undefined Behavior .

So, your loop iterations and the array sizes should match ie 10 iterations and 10 memory locations to write to.

It's better to use a constant and use that at all places like this:

const int SIZE = 10;

int a[SIZE] = {0}; // initialize if it's not an overhead for arduino

for (int i = 0; i < SIZE; i++) {
    a[i] = analogRead(sensor1);
    // ...
}

sortArray(a, SIZE);

Answer 2

You have a somewhat bigger problem with this code.

You simply cannot "print outputs in sorted order" while you are still collecting them. You don't know whether the "smallest" right now should be printed, or wait because an even smaller one is forthcoming.