Lesson 19: Looping Structures: The for Loop
The for loop is ideal when the number of iterations is known beforehand or when you need a clear structure for initialization, condition checking, and updating.
for Loop Syntax
c for (initialization; condition; increment/decrement) { // Code block to execute }
The Three Expressions
- Initialization: Executed only once at the start of the loop (e.g.,
int i = 0;). - Condition: Checked before every iteration. If True, the loop continues.
- Increment/Decrement (Update): Executed after the loop body runs, typically used to progress the loop control variable.
Example: Iterating 0 to 9
c #include <stdio.h>
int main() { int i; // i starts at 0, runs while i < 10, i increases by 1 each time for (i = 0; i < 10; i++) { printf("i is: %d\n", i); } return 0; }
Nested Loops
You can place one loop inside another. This is commonly used for iterating over 2D data structures (like tables or matrices).
c // Example: Printing a 3x3 grid for (int row = 1; row <= 3; row++) { for (int col = 1; col <= 3; col++) { printf("(%d, %d) ", row, col); } printf("\n"); // Move to the next line after finishing a row }