Three equivalent ways to loop over an 2D array. the second one has less indentation.

MatrixLoop.cs

/*
    watching this video: https://unity3d.com/learn/tutorials/modules/advanced/scripting/procedural-cave-generation-pt1
    made me scream because of this much copy-and-paste the nested-loop thing
    
    so here are a few workarounds:
*/ 

int width = 3, height = 2;
int[,] fields = new int[height, width]; // (m x n)-matrix
// ---------------------
// the original:
for (int y = 0; y < height; ++y) {
    for (int x = 0; x < width; ++x) {
        var field = fields[y, x];    
    }
}
// ---------------------
// a 1-line alternative
for (int x = 0, y = 0; y < height; x = (x + 1) % width, y += Convert.ToInt32(x == 0)) {
                                // maybe replaced with: y += x == 0 ? 1 : 0
    var field = fields[y, x];
}
// ---------------------
// Make-A-Method-For-It & Delegates-Are-Fun

public delegate void Stuff(ref int f);  // we need the delegate for the "ref" parameter, this allows us to modify the object
public static void DoStuff(int[,] fields, Stuff stuff) {
    for (int x = 0, y = 0; y < fields.GetLength(0); x = (x + 1) % fields.GetLength(1), 
                                                    y += Convert.ToInt32(x == 0)) {
        var field = fields[y, x];
        stuff(ref field);
    }
}

DoStuff(fields, (ref int field) => { /*... do stuff ...*/ });   // calls the method above like this, looks rly clean