A common mistake when first encountering assert() is to treat it as a general-purpose runtime check — a way to validate user input or to guard against missing files. It is none of those things. Assertions and error handling solve different problems,…
#053 – Input validation in C++. Why std::cin >> x is fragile – Part 1 catalogued the three ways std::cin >> x can fail: the stream entering a fail state, leftover characters in the buffer, and semantically invalid input. By the end…
Most programs prompt the user for input at some point — a menu choice, a configuration value, a calculator’s operands. The natural tool for the job is std::cin >> x, and it works perfectly when the user cooperates. However, we can’t…
051 – Introduction to random number generation in C++ covered the theory of pseudo-random number generation in C++ and ended with stating that the Mersenne Twister is the most plausible engine for non-cryptographic work in native C++. This Nibble shows…
An application might need to generate random numbers for various reasons. Calculating damage in games, statistical modelling and cryptography. Unfortunately, computers are incapable of generating truly random numbers, since their designed to be deterministic. Thus, a contradiction appears. The workaround…
Program flow in control loops can be manipulated using break, return, continue. Whilst their similar in that they end the current iteration, they each have some slight nuances. One program, three exits Consider the program below: If we choose to…
Consider a program that implements a navigation screen using a switch/case block. Each case ends with a break. This ensures that a case doesn’t bleed into the next case, thereby preventing fallthrough. When the the customer wants to enter expenses…
Consider this program. The conditional statement will always be true! Thus, we can label the if statement as constexpr. What is a if constexpr statement? C++17 introduced if constexpr, and most explanations stop at “the compiler evaluates the condition at compile…
Everyone’s familiar with if/else conditional statements. However, there are three variants that differ slightly: Chained vs. independent: a side-by-side Consider two functions modelling a security system. securityPriority() uses a chained if/else if; securityDiagnostic() uses independent ifs. In the first function, which is…
Shipping a new version of a function without breaking existing callers is a recurring problem in library design. Renaming the function forces an update to every caller; leaving it alone means living with the old behaviour forever. C++ offers a…