The C standard library provides a complete set of string functions in <string.h>. Unlike higher-level languages, C strings are just null-terminated arrays of char — there is no built-in string type, so these functions do the work that other languages bake into the runtime. This guide covers every function you will use regularly, with a …

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An interrupt is a hardware signal that suspends the CPU’s current execution, saves the processor state, runs a dedicated function called an Interrupt Service Routine (ISR), then restores the state and resumes where it left off. Interrupts let embedded firmware react to events — a byte arriving on UART, a button press, a timer expiry …

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Memory-mapped I/O in C is how embedded software controls hardware. Instead of using special CPU instructions to access devices, the processor maps hardware control registers to ordinary memory addresses. A C pointer dereferenced at that address reads or writes the hardware directly — toggling an LED, configuring a timer, or sending a byte over UART …