TO's code:
// dos.ino
// 30.3.18
int tab[5][5] = // 5 * 5
{ {1, 2, 3, 4, 5},
{2, 3, 4, 5, 6},
{3, 4, 5, 6, 7},
{4, 5, 6, 7, 8},
{5, 6, 7, 8, 9} };
void setup() {
Serial.begin(115200);
pinMode(13, OUTPUT); // BlinkLED
Serial.println("===================================");
Serial.println("======================= dos.ino ===");
Serial.println("===== 30.3.18 =====================");
int sum_horizontal = 0;
int sum_total = 0;
int sum_vertical = 0;
int sum_diagonal1 = 0; // lo-ru result I = 25
int sum_diagonal2 = 0; // ro-lu result II = 15
int sum_diagonal3 = 0; // lu-ro result III = 0
int sum_diagonal4 = 0; // ru-lo result IV = 0
int product_tab = 0; // ????
byte i, j;
//--------------------------------------------------
Serial.println(" this is the array :");
// Serial.println();
for (i = 0; i < 5; i++)
{ for (j = 0; j < 5; j++)
Serial.print(tab[i][j]);
{
Serial.println();
}
}
Serial.println();
//-----------------------------------
for (i = 0; i < 5; i++)
{ for (j = 0; j < 5; j++)
{ sum_total += tab[i][j]; //
}
}
Serial.print(" totalsum = ");
Serial.print(sum_total);
Serial.println();
// -------------------------------------------------------------
for (i = 0, j = 0; i < 5, j < 5; i++, j++) // j = lines
{ // i = columns
sum_diagonal1 += tab[i][j];
}
Serial.print(" diagonal-sum 1 = "); // I top-down, left-right
Serial.println(sum_diagonal1);
// ---------------------------------------------------------------
for (i < 5, j = 0; i = 0, j < 5; i--, j++)
{
sum_diagonal2 += tab[i][j];
}
Serial.print(" diagonal-sum 2 = "); // II top-down, right-left
Serial.println(sum_diagonal2);
// ----------------------------------------------------------------
for (i = 0, j < 5; i < 5, j = 0; i--, j++)
{
sum_diagonal3 += tab[i][j];
}
Serial.print(" diagonal-sum 3 = "); // III bottom-up, left-right
Serial.println(sum_diagonal3);
// -----------------------------------------------------------------
for (i < 5, j < 5; i = 0, j = 0; i--, j--)
{
sum_diagonal4 += tab[i][j];
}
Serial.print(" diagonal-sum 4 = "); // IV bottom-up, right-left
Serial.println(sum_diagonal4);
// ----------------------------------------------------------------
for (i = 0; i < 5; i++)
{ for (j = 0; j < 5; j++)
{
sum_horizontal += tab[i][j];
}
}
Serial.print(" horizontal = "); //
Serial.println(sum_horizontal);
for (j = 0; j < 5; j++)
{ for (i = 0; i < 5; i++)
{
sum_vertical += tab[i][j];
}
}
Serial.print(" vertical = ");
Serial.println(sum_vertical);
}
void loop() {
digitalWrite(13, millis() >> 9 & 1);
}
If you turn on warnings (File / Preferences / Show verbose output during compilation CHECK) you get some of them when compiling your code, like:
warning: left operand of comma operator has no effect [-Wunused-value]
for (i = 0, j < 5; i < 5, j = 0; i--, j++)
^
For proper use of for statements take a look here (for example): http://www.learncpp.com/cpp-tutorial/57-for-statements/