Search⌘ K
AI Features
Home
Courses
Learn C Fundamentals

Writing to Arrays

Understand how to write values to specific array cells safely and the risks of out-of-bounds access in C. Learn different methods to initialize one-dimensional arrays, including partial initialization, and discover principles for working with multi-dimensional arrays to handle complex data efficiently.

We'll cover the following...

Assigning values to array cells

A memory location indexed by an array (for example grades[3]) is called a cell of that array. Just like we index an array to retrieve the value stored in it, we can also write to the same cell.

We can assign the integers 1 through 5 to the cells in our grades array like this:

C
#include <stdio.h>
int main(void)
{
  int grades[5];
  int i;
  for (i = 0; i < 5; i++) {
    grades[i] = i+1;
    printf("grades[%d] = %d\n", i, grades[i]);
  }
  return 0;
}

What can be dangerous however, is that we can also ask C to assign values to memory locations beyond the bounds of an array and C won’t complain:

C
#include <stdio.h>
int main(void)
{
  int grades[5];
  grades[5] = 999;
  grades[500] = 12345;
  printf("grades[500] = %d\n", grades[5]);
  printf("grades[500] = %d\n", grades[500]);
  return 0;
}

The reason this is ...