-03 The IPO Model

The std::setw(int n) manipulator sets the width of the next output field to n characters.

The std::setfill(char c) manipulator sets the fill character used when the output is shorter than the specified width, with the default being a space character.

The std::setprecision(int n) manipulator sets the number of digits displayed after the decimal point for floating-point numbers.

Using std::fixed forces floating-point numbers to be displayed in fixed-point notation.

The std::scientific manipulator forces floating-point numbers to be displayed in scientific notation.

The std::showbase flag displays the base prefix for octal (0) and hexadecimal (0x) numbers.

The IPO model stands for Input, Processing, and Output.

The three main steps in the IPO model are:

1. Input and store the raw data
2. Process the data by performing the required operation
3. Output the result of processed data (information)

Input statements are used to get raw data from the external environment, such as the user, and store it in variables.

The main input statement in Python is input(), which retrieves a string corresponding to a line of input from the user.

The optional string argument in the input() function is known as a prompt, which provides a message to hint the user about what input is expected.

To convert input data to other types in Python, you must convert the string input after it is received. For example:

• the_number = int(rawinput) converts a string to an integer.
• std_count = int(input("How many students in the class?")) converts input to an integer.
• gpa = float(input("What is your GPA?")) converts input to a float.

In Python, multiple items can be input from one line by using the input() function followed by the split() method. This allows the user to enter data separated by spaces, which is then split into a list of items. For example:

1. Use dataline = input("Please input hour and charges:")
2. Split the input with data = dataline.split()
3. Access individual items using indexing, e.g., hour = int(data[0]) and charges = float(data[1]).

The input() function in Python reads input data from the current line up to the end-of-line. Each call to input() captures the entire line as a string, allowing for line breaks to separate different inputs if needed.

In C++, multiple variables can be input in a single line using the std::cin stream. The input is taken in the order the variables are declared. For example:

1. Declare variables: int num, cnt; float amt;
2. Input multiple variables in one line: std::cin >> num >> amt;
3. Input a single variable: std::cin >> cnt;

In C++, spaces, tabs, and newlines in the input stream are treated as separators for input data. They are automatically skipped by the input stream to find the next input data, allowing for flexible input formatting.

An assignment statement is an instruction that puts values into variables. It replaces the old value in a variable with a new value using the assignment operator '='. The syntax is:

variable = expression

For example, in Python:

variable1 = 2 + 3 * 4
str1 = "This is a string."
counter = 1
counter = counter + 1

The two steps involved in processing an assignment statement are:

1. Evaluate the right-hand side expression to calculate its value.
2. Store the result of the evaluation into the variable(s) indicated on the left-hand side.

An expression can consist of:

• Constant literals: e.g., 4, 58, 395.8, 's'
• Operators: e.g., +, -, *, /
• Variables: e.g., cnt, apples

Examples of expressions include:

• 1 + 2
• 3 + 2 * (6 + (var1 - 1) / 12)
• cnt

The std::showpoint flag forces the display of the decimal point for floating-point numbers, even if there are no digits after it.

The std::showpos flag displays a plus sign (+) for positive numbers in the output.

In C/C++, if both a and b are integers, the result is an integer. In Python, the result is always a float type.

In C/C++, integer division results in an integer if both operands are integers. In Python, using a // b results in an int if both a and b are int (round down), otherwise, it results in a float (round down).

In C/C++, the result is 2 (integer division). In Python, the result is 2.5 (floating point division).

The modulus operator (%) finds the remainder of integer division.

In both C/C++ and Python, the result of the expression 15 % 4 is 3.

In boolean operations, 1 represents true (or True in Python) and 0 represents false (or False in Python).

For A=1 and B=1:

• A AND B = 1
• A OR B = 1
• A XOR B = 0
• NOT A = 0

The bitwise logic operators for both C/C++ and Python are:

• & (AND)
• | (OR)
• ~ (NOT)
• ^ (XOR)

In bitwise logical operations, the operands are treated as binary numbers, and the logical operation is performed for the corresponding bit pairs in the operations.

The shift left operation moves every bit in a binary number 1 (or more) position(s) to the left, filling the LSB with 0. It is represented by the operator << and shifting left by n positions is equivalent to multiplying the number by 2^n. However, in C/C++, this may result in overflow.

The two types of shift right operations are unsigned shift right (logical shift right) and signed shift right. They both shift the binary bits 1 (or more) position(s) to the right but differ in how the MSB is filled:

• Unsigned shift right replaces the MSB with 0.
• Signed shift right copies the original MSB as the new MSB.

The result of shifting the number 35 right by 1 position using unsigned shift right is 17 (35 >> 1 = 17).

In signed shift right, the operation shifts the binary bits to the right and copies the original MSB as the new MSB. For example, -35 >> 2 results in -8. This operation is equivalent to dividing by 2^n, with the exception of the number -1.

In Python, the precedence of the ** operator (exponentiation) is 14, which is the highest precedence level.

In C/C++, a smaller precedence number indicates higher precedence, while in Python, a larger precedence number indicates higher precedence. For example, in C/C++, the ** operator has a precedence of 15 (low), whereas in Python, it has a precedence of 14 (high).

The result of the expression 'num * (value + 3)' is 23 * (3 + 3) = 23 * 6 = 138.

The steps involved are:

1. Evaluate the expression to compute its value.
2. Store the computed value in the variable.

In Python, the precedence of the 'and' operator is 4, which is lower than the precedence of the 'not' operator (5) and higher than the 'or' operator (3).

Short-hand (compound) assignment allows for more concise expressions in both C/C++ and Python. For example:

In C/C++, the special expressions for auto increment and decrement are:

• v++ is a reference before the increment.
• ++v is an increment before the reference.

When using auto increment/decrement (like v++ or ++v) as part of an expression, it can be hard to understand. It is recommended to avoid using them in expressions unless you are very clear about the outcome. Instead, use them as standalone statements.

In C/C++, you can calculate the square root using the sqrt function from the cmath library:

#include <cmath>
float x;
std::cin >> x;
std::cout << sqrt(x);

In Python, you can use the sqrt function from the math library:

import math
x = float(input())
print(math.sqrt(x))

An output statement is used by a computer to present or inform users about the results of data processing.

The syntax for printing multiple items in Python is:

print (expression, ... [, sep=""] [, end="\n"])

You can print multiple items on separate lines in Python by using multiple print statements:

print("Item:", cnt)
print("Total:", amt)

The syntax for outputting data in C++ is:

std::cout << expression << ...;

The default ending character is a newline '\n'.

You can change the ending character by using the optional argument end=''.

F-strings are a way to embed expressions inside string literals by prefixing the string with 'f', available from Python 3.6 onwards.

You can left align a number by using the format specifier '<' followed by the width, e.g., f'{cnt:<20}'.

The format specifier '.3f' is used to format a floating-point number to 3 decimal places.

You can center align a number by using the format specifier '^' followed by the width, e.g., f'{cnt:^20}'.

The main output statement in C is printf() with the syntax: printf("formatting-string", exp1, exp2, ...);

Both f-string in Python and printf in C are used for formatted output. However, f-strings provide a more concise and readable way to embed expressions inside string literals, while printf requires a format string and separate arguments for each value.

The negative number in the printf format specifier indicates left alignment of the output. For example, %-20d aligns the integer to the left within a field of 20 characters.

The format specifier %.2f in the printf function formats a floating-point number to two decimal places.

The iomanip manipulators are used to control the formatting of output in C++. They allow for setting the width of output fields, controlling the number of decimal places for floating-point numbers, and other formatting options.

The std::setw manipulator sets the width of the next output field. In the code, it is used to ensure that the integer cnt is printed with a width of 10 characters, which can help align output when printing multiple values.

Using std::fixed ensures that the floating-point number amt is printed in fixed-point notation, which means it will display a fixed number of decimal places. In the provided code, it results in 120.500000 being printed instead of a potentially more concise representation.

These manipulators control the alignment of output within a field: std::left aligns text to the left, std::right aligns it to the right, and std::internal aligns signs and digits appropriately.

These manipulators set the numeric base for integer output: std::dec for decimal (base 10), std::hex for hexadecimal (base 16), and std::oct for octal (base 8).

The std::setbase(int base) manipulator sets the numeric base (e.g., decimal, octal, hexadecimal) for integer input and output.

The std::fixed manipulator is used to format floating-point numbers in fixed-point notation, ensuring that the output displays a fixed number of decimal places instead of scientific notation.

The std::setprecision manipulator sets the number of digits to be displayed after the decimal point for floating-point numbers when used with std::fixed. For example, std::setprecision(2) will display two decimal places.

The std::setw manipulator sets the width of the next output field. If the output is shorter than the specified width, it will be padded with spaces to the left by default.

These manipulators change the base of the integer output: std::dec outputs in decimal (base 10), std::hex outputs in hexadecimal (base 16), and std::oct outputs in octal (base 8).

The std::showbase manipulator adds a prefix to the output: '0x' for hexadecimal and '0' for octal, indicating the base of the number being displayed.