Arduino 8x8 LED矩阵不会关闭

Question

So i'm learning how to control an 8x8 LED matrix with an arduino, however for some reason my code isn't working. I've got 8 rows(each attached to it's own pin, from 12 - 5), and 4 columns(each with it's own pin, pins 0-3) working at the moment. I want to make a snake kind of design with my LEDs, so it moves diagonally. the code was working, and then i decided to add two rows of code(which i've deleted now) and it's still not working. What happens is all of the LEDs light up perpetually, instead of one at a time.

EDIT: I know that use of delay is generally not good, as well as the fact i should have used a switch case, but I figured this was simple enough to not have to worry about it.

Here's the code:

int pinnum = 13;
int lastpin = 0;
int col = 0;
int k;

void setup() {  //runs once
//  initialize pins as outputs
  for(int pinnum; pinnum >= lastpin; pinnum--) 
  {
    pinMode(pinnum, OUTPUT);
  }
  for(int i = 5; i <= 13; i++) //starts with all of them off
  {
    digitalWrite(i,LOW);
  }
  for(int i = 0; i <= 4; i++) //starts with all of them off
  {
    digitalWrite(i, HIGH);
  }

}//   END SETUP

void loop() {

 pinon(12);
 togglecol();
 delay(1000);

 pinon(11);
togglecol();
 delay(1000);

 pinon(10);
 togglecol();
 delay(1000);

 pinon(9);
 togglecol();
 delay(1000);

 pinon(8);
 togglecol();
 delay(1000);

 pinon(7);
 togglecol();
 delay(1000);

 pinon(6);
 togglecol();
 delay(1000);

 pinon(5);
 togglecol();
 delay(1000);
}

void togglecol() 
{
 if(col % 4 == 1) //column = 1, pin 3
 {
  digitalWrite(0, HIGH);
  digitalWrite(1, HIGH);
  digitalWrite(2, HIGH);
  digitalWrite(3, LOW);
 }
 else if(col % 4 == 2) //COLUMN = 2, PIN 2
 {
  digitalWrite(0, HIGH); 
  digitalWrite(1, HIGH);
  digitalWrite(2, LOW);
  digitalWrite(3, HIGH);
 }
 else if(col % 4 == 3) //COLUMN = 3, PIN 1
 {
  digitalWrite(0, HIGH); 
  digitalWrite(1, LOW);
  digitalWrite(2, HIGH);
  digitalWrite(3, HIGH);
 }
 else if(col % 4 == 0) //  COLUMN 3, PIN 0
 {
  digitalWrite(0, LOW); 
  digitalWrite(1, HIGH);
  digitalWrite(2, HIGH);
  digitalWrite(3, HIGH);
 }
 col++;
} //END TOGGLECOL



void pinon(int pin)
{
  for(k = 5; k <= 13; k++)  //turning all rows off
  {
    digitalWrite(k, LOW);
  }
    digitalWrite(pin, HIGH); //activating correct row again
}//END PINON`

Answer 1

So I think at least one error is right here

void setup() {  //runs once
//  initialize pins as outputs
  for(int pinnum; pinnum >= lastpin; pinnum--) 
  {
    pinMode(pinnum, OUTPUT);
  }

above this you set pinnum = 13 But then in your for loop you say for(int pinnum...

This reinitializes pinnum to 0 so your for loop is not exicuting.

You can test this therory here http://www.compileonline.com/compile_cpp_online.php

Just copy and paste in the following and hit compile to see the difference

//Working for loop

#include <iostream>

using namespace std;

int main()
{
   cout << "Hello World" << endl; 
   int a = 10;

   for(a; a>0; a--){
      cout << a << endl;       
   }
   return 0;
}

Then try

//For loop like yours
#include <iostream>

using namespace std;

int main()
{
   cout << "Hello World" << endl; 
   int a = 10;

   for(int a; a>0; a--){
      cout << a << endl;           
   }
   return 0;
}