I wanted to declare a 2D array and assign values to it, without running a for loop.
I thought I could used the following idea
int array[5] = {1,2,3,
The proper way to initialize a multidimensional array in C or C++ is
int arr[2][5] = {{1,8,12,20,25}, {5,9,13,24,26}};
You can use this same trick to initialize even higher-dimensional arrays if you want.
Also, be careful in your initial code - you were trying to use 1-indexed offsets into the array to initialize it. This didn't compile, but if it did it would cause problems because C arrays are 0-indexed!