Nesting Loops
A nested loop refers to a loop that is contained within another loop. It allows you to iterate over multiple sets of data simultaneously, performing certain operations for each combination of values. The inner loop executes in its entirety for each iteration of the outer loop. For example:
for i in range(1, 4): # outer loop
for j in range(1, 4): # inner loop
print(i, j)
# Output:
# 1 1
# 1 2
# 1 3
# 2 1
# 2 2
# 2 3
# 3 1
# 3 2
# 3 3
In this code above, there are two loops: an outer loop that iterates over the values 1, 2, and 3, and an inner loop that also iterates over the values 1, 2, and 3. For each iteration of the outer loop, the inner loop executes completely, resulting in the printing of all combinations of i and j values.
Nested loops are useful in situations where you need to perform repetitive operations on combinations of values, such as when working with matrices, multidimensional arrays, or nested data structures.