Array - C

Arrays

A sequence of values back to back (contiguous) in memory all of which is the same data type

• a data structure

Declaration

• type name[size];

# individual element syntax
int scores[3];
scores[0] = 72;
scores[1] = 73;
scores[2] = 33;
 
# instantiatino syntax
bool truthtable[3] = {false, true, true}
bool truthtable[] = {false, true, true} 
// size is optional in instantiatino syntax  

• In C, if you pass an array as input to a function, you have to also pass another argument of how big the array is as well
  • float average(int length, int array[])

String

• String is an array of chars

string s = "HI!";
printf("%c %c %c", s[0], s[1], s[2]); 

• use string.h

NUL

• the last byte of a string will always be 0, a special delimiting character NUL

string s = "HI!";
printf("%i %i %i %i\n", s[0], s[1], s[2], s[3]); // 72 73 33 0

• the variable indicate where the string begins, the 0 indicate where the string ends
• The double quotes imply that it’s a string & it needs to be terminated with backslash 0

int main(void)
{
	string s = get_string("Input: ");
	printf("Output: ");
	// inititalize strlen here too!!
	for (int i = 0, n = strlen(s); i < n; i++)
	{
		printf("%c", s[i]);
	}
	print("\n");
}

Multi-dimension

• Arrays can consist of more than a single dimension
  • You can have as many size specifiers as you wish
• bool battleship[10][10]
  • 10 x 10 grid of cells
  • In memory though, it’s just a 100-element 1D array
• Multi-dimensional arrays are great abstractions to help visualize gameboards or other complex representations
• We can’t treat entire arrays themselves as variables
  • we CANNOT assign one array to another using the assignment operator (not legal C)
  • we must use a loop to copy over the elements one at a time