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I have a 2d and i want to set the elements to zero without looping all the elements
int a[100][200];
I can't initialize them at point of declaration.
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A multidimensional array in C is nothing more than an array of arrays. Any object can be initialized to “zero” using an initializer of = { 0 } . For example: double two_dim_array[100][100] = { 0 };
Different Methods to Initialize 2D Array To Zero in C++int array[100][50] = {0}; The above code initialize a 2D array with all entries 0. The above code snippet actually sets the first element of the array to 0 and sets the rest of the array to 0. For example, if we replace the '0' by some other digits say '1'.
For example:int[][][] arr = new int[10][20][30]; arr[0][0][0] = 1; The above example represents the element present in the first row and first column of the first array in the declared 3D array. Note: In arrays if size of array is N. Its index will be from 0 to N-1.
2-D Array filling using std::fill or std::fill_n flags[0][0], &a. flags[0][0] + sizeof(a. flags) / sizeof(a. flags[0][0]), '0'); // or using `std::fill_n` // std::fill_n(&a.
For C++, you can use the std:fill method from the algorithm header.
int a[x][y];
std::fill(a[0], a[0] + x * y, 0);
So, in your case, you could use this:
int a[100][200];
std::fill(a[0], a[0] + 100 * 200, 0);
Of course, the 0 could be changed for any int value.
72
Try
int a[100][200] = {{0}};
If you initialize some (but not all) of the elements, the rest will be initialized to zero. Here, you are only explicitly initializing the first element of the first sub-array and the compiler is taking care of the rest.
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