For Loop

A for loop in C is a control flow statement for repeated execution of a block of code. Very similar to Python, but with a different syntax.

The syntax of a for loop in C consists of three main parts:

Initialization
Condition
Final-expression.

There is no "for each" (iterables) in C. For example, there is no way to do:

for car in cars:
    print(car)

Instead, we have to iterate over the numbers of indices in a list, and then we can access the item using the index.

Syntax

for (initialization; condition; final-expression) {
    // Loop Body
}

Parts of a `for` Loop

Initialization
- Executed only once at the beginning of the loop.
- Is typically used to initialize the loop counter: int i = 0; for example
Condition
- Checked before each iteration.
- If true, execute the body. If false, terminate the loop
- Often checks to ensure i is less than some value: i < 5; for example
Final-expression
- Executed after each iteration of the loop body.
- Can be used to update the loop counter or run any other code: i++ for example
Loop Body
- The block of code that is executed while the condition is true.

Example: Basic Loop

#include <stdio.h>

int main() {
  for (int i = 0; i < 5; i++) {
    printf("%d\n", i);
  }
  return 0;
}

// Prints:
// 0
// 1
// 2
// 3
// 4

Assignment

Implement the print_numbers prototyped in exercise.h that takes a starting number and an ending number and prints all the numbers in that range inclusive (using a for-loop).

For Loop

Syntax

Parts of a for Loop

Example: Basic Loop

Assignment

Parts of a `for` Loop