Multidimensional array with unequal second dimension size using malloc()
c, malloc, multidimensional-array
Solution
No, The address a[1][3] does not "officially exist". It is a memory which is not define in your program and accessing it result in a undefined behavior.
It can lead to the following error:
- Segmentation fault (access a restricted memory)
- Used a memory already used by other variable (other allocation memory) (so possible overwrite)
- It can be an uninitialized value (unsused memory address)
Problem
I am playing around with multidimensional array of unequal second dimension size. Lets assume that I need the following data structure: [&ptr0]->[0][1][2][3][4][5][6][7][8][9] [&ptr1]->[0][1][2] [&ptr2]->[0][1][2][3][4] ``` int main() { int *a[3]; int *b; int i; a[0] = (int *)malloc(10 * sizeof(int)); a[1] = (int *)malloc(2 * sizeof(int)); a[2] = (int *)malloc(4 * sizeof(int)); for(i=0; i<10; i++) a[0][i]=i; for(i=0; i<2; i++) a[1][i]=i; for(i=0; i<4; i++) a[2][i]=i; } ``` I did some tests and it seems like I can store a value at a[1][3]. Does it mean that rows in my array are of equal size 10?