update C 2D arrays

.vscode/tasks.json

@@ -2,8 +2,8 @@
   "tasks": [
     {
       "type": "cppbuild",
-      "label": "C/C++: g++ build active file",
-      "command": "/usr/bin/g++",
+      "label": "C/C++: gcc build active file",
+      "command": "/usr/bin/gcc",
       "args": [
         "-fdiagnostics-color=always",
         "-g",

code_examples/5-Holding_Data/1-Arrays/2-Array_as_a_Return_Value/C/main.c

@@ -8,37 +8,44 @@
 #include <stdlib.h>
 #include <time.h>
 
-// in C an array is passed by reference to a function
-int sumOfNumbers(int arrayOfNumbers[]) {
+// in C you must pass in the size of the array to a function
+int sumOfNumbers(int lengthOfArray, int widthOfArray, int arrayOfNumbers[lengthOfArray][widthOfArray]) {
     // this function adds up all of the numbers in the list
 
     int total = 0;
-    int counter;
-    int lengthOfArray = sizeof(arrayOfNumbers) / sizeof(arrayOfNumbers[0]);
+    int counterLength;
+    int counterWidth;
 
-    for (counter = 0; counter < lengthOfArray; counter++) {
-        total += arrayOfNumbers[counter];
+    for (counterLength = 0; counterLength < lengthOfArray; counterLength++) {
+        for (counterWidth = 0; counterWidth < widthOfArray; counterWidth++) {
+            total += arrayOfNumbers[counterLength][counterWidth];
+        }
     }
 
     return total;
 }
 
 int main() {
     // this function uses an array
-    int numberList[10];
+    // remember in C you must know the array size at compile time
+    const int lengthOfArray = 10;
+    const int widthOfArray = 5;
+    int numberList[lengthOfArray][widthOfArray];
     int seed = time(NULL);
 
     // input
-    for (int counter = 0; counter < 10; counter++) {
-        srand(seed);
-        int aSingleRandomNumber = rand_r(&seed) % 100;
-        numberList[counter] = aSingleRandomNumber;
-        printf("The random number is: %d\n", aSingleRandomNumber);
+    srand(seed);
+    for (int counter1 = 0; counter1 < lengthOfArray; counter1++) {
+        for (int counter2 = 0; counter2 < widthOfArray; counter2++) {
+            int aSingleRandomNumber = rand_r(&seed) % 100;
+            numberList[counter1][counter2] = aSingleRandomNumber;
+            printf("The random number is: %d\n", aSingleRandomNumber);
+        }
     }
     printf("\n");
 
     // call function
-    int sum = sumOfNumbers(numberList);
+    int sum = sumOfNumbers(lengthOfArray, widthOfArray, numberList);
 
     // output
     printf("The sum of all the numbers is: %d\n", sum);