Question

Write statement(s) for each of the following: a) Print integer 40000 right justified in a 15 -digit ficld. b) Print 200 with and without a sign. c) Print 100 in hexadecimal form preceded by \(0 x\) d) Print 1.234 with three digits of precision in a nine-digit ficld with preceding zeros.

Short answer

Use `printf` with specific format specifiers: `%15d`, `%+d`, `%d`, `0x%x`, `%09.3f`. Adjust as shown in each step.

Step-by-step solution

Formatting an Integer Right Justified

To print the integer 40000 right-justified in a 15-digit field, use the formatting code: `printf("%15d", 40000);` Here, `%15d` specifies a decimal integer in a width of 15 characters, which will right-align the number by default.

Printing an Integer with and without Sign

To print the integer 200 with a sign, use the formatting code: `printf("%+d", 200);` To print it without a sign, use: `printf("%d", 200);` Here, `%+d` ensures that a positive sign (+) is included, and `%d` prints the number without a sign.

Printing in Hexadecimal Format

For printing the integer 100 in hexadecimal with a prefix `0x`, use: `printf("0x%x", 100);` The `%x` format specifier converts the integer to a lowercase hexadecimal representation, while manually prefixing with `0x` is required.

Printing a Float with Preceding Zeros

To format the float 1.234 with three digits of precision in a nine-digit field with zeros, use: `printf("%09.3f", 1.234);` In the format `%09.3f`, "9" specifies the width (including decimal point and digits), and ".3" specifies three digits after the decimal. The leading zero ensures the field is padded with zeros.

Key concepts

printf formatting

In Java programming, `printf` is a very useful method that allows you to format output neatly. This function is widely used due to its ability to customize output precisely. The syntax involves a format string containing placeholders for variables. Each placeholder starts with a `%` symbol followed by a character indicating the data type.

Here are some common format specifiers used with `printf`:

• `%d` for decimal integers.
• `%f` for floating-point numbers.
• `%c` for characters.
• `%s` for strings.

These placeholders allow you to control how numbers or text is output, making your printouts even more readable.
This method works similarly to the `printf` function found in C, but it's available in Java to provide flexibility in formatting text output.

integer right justification

Right justification of integers in Java using `printf` lets you align numbers neatly, which is particularly helpful when displaying tabular data. To achieve right justification, you specify the width of the output field using the `%d` format specifier, followed by a number representing the total width.

For example, in `printf("%15d", 40000);`, the number `15` sets the field width to 15 characters. This means the integer `40000` is right-aligned within this space. Such formatting is crucial for generating reports where alignment and readability are key.
Additionally, this technique ensures that, irrespective of the number's size, it occupies the same space on the screen, improving the aesthetic appeal and organization of your output.

hexadecimal output

Hexadecimal output is an efficient way to represent integer values, especially when dealing with memory addresses or color codes in programming. Java's `printf` method can output integers in hexadecimal form through the `%x` specifier. By default, this gives a lowercase representation.

To add the common `0x` prefix to a hexadecimal number, you'll need to include it manually in the format string, like this: `printf("0x%x", 100);`. This indicates that the number following `0x` is in hexadecimal.
Using hexadecimal can simplify the representation of large numbers, making it easier to work with certain types of data in your Java applications. It is also beneficial in cases involving bitwise operations, as hexadecimal digits correspond directly to four binary digits, making them ideal for such tasks.

floating-point precision

Floating-point precision in Java is essential for working with values that require decimal points. Controlling this precision becomes crucial when you want to display just a few decimal places for a number. The `%.nf` specifier in `printf` allows you to set this precision.

For instance, `printf("%.3f", 1.234)` will display `1.234` with three decimal spaces. Here, the `3` specifies the number of digits to show after the decimal point.
Moreover, to ensure the entire output takes a specific width, consider padding with zeros. For example, `printf("%09.3f", 1.234)` creates a nine-character wide field filled with zeros where necessary. This preserves a uniform layout, perfect for financial reports and scientific data, where precision and consistent format are required.