Question

Write a function that takes the time as three integer arguments (hours, minutes and seconds) and returns the number of seconds since the last time the clock “struck 12.” Use this function to calculate the amount of time in seconds between two times, both of which are within one 12-hour cycle of the clock.

Short answer

To calculate the amount of time in seconds between two times within a 12-hour cycle, define a function that translates time into seconds since 12 o'clock and use it to determine the difference between the two times.

Step-by-step solution

Define the function

Create a function named 'time_since_struck_twelve' that takes three parameters: hours, minutes, and seconds. This function will calculate the total number of seconds that have passed since the last time the clock struck 12. To do this, convert the hours to seconds by multiplying by 3600, the minutes to seconds by multiplying by 60, and add them together along with the seconds.

Handle the hour conversion

Within the function, you need to handle the conversion of hours into seconds. Since we’re working with a 12-hour clock, if the input is 12 hours, it should be treated as 0 hours. Subtract 12 from the hours if the 'hours' parameter is 12, then multiply the result by 3600 to convert to seconds.

Calculate total seconds

Add the converted hours, converted minutes (minutes multiplied by 60), and seconds to get the total seconds since the clock struck 12.

Define a second function to calculate the difference

Define another function named 'seconds_between_times' that takes two sets of hours, minutes, and seconds. It will use the 'time_since_struck_twelve' function for each time and return the absolute difference between the two times in seconds.

Calculate the time difference

Call 'time_since_struck_twelve' for both sets of input times, then subtract one from the other and take the absolute value of the result to get the number of seconds between two times.

Key concepts

Functions in C++

In the realm of programming, particularly in C++, a function is akin to a structured block dedicated to performing a specific task. These modular units of code not only enhance readability but also facilitate code reuse and maintainability.

A function in C++ is declared with a return type, a unique identifier known as its name, and an optional list of parameters enclosed in parentheses. These parameters act as input variables specific to the function's scope. After declaring a function, you must define what it does within its body, enclosed by curly braces.

For the given exercise, C++ functions play a critical role. The 'time_since_struck_twelve' and 'seconds_between_times' functions are the building blocks that encapsulate the logic required to perform time calculations. By employing functions, we create a level of abstraction that allows us to focus on the larger problem without getting bogged down in the minutiae of the computational details.

Time Conversion

Time conversion involves transforming units of time into different formats or scales. This is crucial in time calculations, particularly when we aim to compare times or calculate durations. For example, when we work with standard clocks, we typically see time represented in hours, minutes, and seconds.

In programming, it's often necessary to convert these into a consistent unit to perform arithmetic operations efficiently. In typical scenarios, seconds are the preferred unit because they can express any time duration without requiring fractions. In the exercise, we convert hours to seconds by multiplying by 3600 and minutes to seconds by multiplying by 60. The magic numbers '3600' and '60' are derived from the number of seconds in an hour and a minute, respectively. Hence, when performing these conversions, a solid understanding of the relationships between these units is vital.

Programming Logic

Programming logic forms the brain of a code sequence, enabling a program to make decisions and execute instructions based on given criteria. It is the set of instructions that dictates the flow of control through a program.

Good programming logic is characterized by clarity, adherence to a specific task, handling various scenarios, and efficient execution. When writing programs, logical structures such as conditionals, loops, and function calls come into play to create more complex and functional code.

In the context of the exercise with time calculations, logic is employed to handle the conversion of input times to a common unit, account for the special case when the clock 'strikes 12', and compute the difference between two times with accuracy. It's these logical steps that ensure the program not only runs without errors but produces the correct output for an array of possible inputs.