24sp ver.

Note: this is for the Spring 2024 iteration of CSE 121. Looking for a different quarter? Please visit https://courses.cs.washington.edu/courses/cse121/.

## Nested For Loops¶

(loops inside loops, can be used to produce complex text patterns)

#### Example

``````for (int i = 1; i <= 5; i++>) {
for (int j = 1; j <= (5 - i); j++) {
System.out.print(".");  // print dots
}
System.out.println(i);  // print line number
}
``````

#### Output

``````....1
...2
..3
.4
5
``````

### Update Statements¶

(common update statements in for loops)

Statement Description
`i++` increment `i` by `1`; same as `i = i + 1`
`i += 1` increment `i` by `1`; same as `i = i + 1`
`i--` decrement `i` by `1`; same as `i = i - 1`
`i -= 1` decrement `i` by `1`; same as `i = i - 1`

## Random¶

(produce random numbers)

``````import java.util.*;  // We must include this in order to use Random!

// Create a Random object
Random rand = new Random();

// Generating values
int a = rand.nextInt(10); // generating an integer in the range of 0 to 9
int b = rand.nextInt(10) + 1; // generating an integer in the range of 1 to 10
int c = rand.nextInt(7) + 4; // generating an integer in the range of 4 to 10
``````

### Methods¶

Method Description
`nextInt()` random integer
`nextInt(max)` random integer between `0` (inclusive) and `max` (exclusive)
`nextDouble()` random double between `0.0` (inclusive) and `1.0` (exclusive)

### Formula for Generating a Random Number between min - max (inclusive)¶

Steps Example
1. What is the desired min? 4
2. What is the desired max? 10
3. Calculate the range = max - min + 1 10 - 4 + 1 = 7
4. Substitute into: `rand.nextInt(range) + min` `rand.nextInt(7) + 4`

## Fenceposting¶

(pulling one iteration out of the loop)

#### Example

``````System.out.print(1);               // one number to start with
for (int i = 2; i <= 5; i++) {
System.out.print(", " + i);    // commas between numbers
}
System.out.println();              // end the line
``````

#### Output

``````1, 2, 3, 4, 5
``````