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← C Programming for Beginners
○What a program actually does○The computer and the operating system○From a C file to a running program○Compiled and interpreted programs○Demo: Trace One Tiny C Program○Exercise: Print the Opening Sign✦Module Quiz
○Your First C Program○Variables and Formatted Output○Arithmetic and Integer Division○Demo: Formatting and Numeric Conversion○Exercise: Calculate a Shop Total✦Module Quiz
○Demo: Declare and initialize variables○Exercise: Declare and initialize variables○Demo: Assign a new value○Exercise: Assign a new value○Demo: Choose int, double, and char○Exercise: Choose int, double, and char○Demo: Keep local names and constants clear○Exercise: Keep local names and constants clear✦Module Quiz
○Demo: Match printf placeholders and arguments○Exercise: Match printf placeholders and arguments○Demo: Build lines with escapes and multiple calls○Exercise: Build lines with escapes and multiple calls○Demo: Print percent signs and aligned values○Exercise: Print percent signs and aligned values○Demo: Evaluate expressions before printing○Exercise: Evaluate expressions before printing✦Module Quiz
○Comparisons and True or False○How if and else Choose a Path○Exercise: Choose a Ticket Message○Demo: Select a Fixed Choice with switch○Exercise: Choose a Service Desk✦Module Quiz
○For Loops: Repeat a Known Number of Times○Exercise: Add Daily Contributions○While Loops: Repeat While a Condition Holds○Exercise: Make a Countdown○Demo: Run Once with do while○Demo: Label a Two-Row Shelf○Exercise: Label Tool Drawers✦Module Quiz
○Define and Call a Function○Follow a Function Call and Its Return Value○Exercise: Return a Square○Demo: Declare Before a Function Call○Exercise: Declare and Convert✦Module Quiz
○Arrays and Zero-Based Indexes○Exercise: Add Array Elements○Demo: Count Array Slots Safely○Exercise: Average Workshop Ratings○Demo: Rows and Columns in Memory○Exercise: Total a Two-Row Grid✦Module Quiz
○C Strings and the Null Terminator○Exercise: Count a Label○Demo: Compare Complete Strings○Exercise: Verify a Pickup Code○Demo: Visit Each Character○Exercise: Count a Letter in a Label✦Module Quiz
○Pointers: Addresses and Dereferencing○Exercise: Update Through a Pointer○Demo: Pass an Address to a Function○Exercise: Swap Two Counts○Demo: Array Addresses and Offsets○Exercise: Total with an In-Bounds Pointer○Demo: Null, Validity, and Lifetime○Exercise: Handle an Optional Pointer✦Module Quiz
○Demo: Pass an Array and Its Length○Exercise: Total Readings in a Function○Demo: Change Array Elements Through a Parameter○Exercise: Update Each Stock Count✦Module Quiz
○Define a Supply Record○Exercise: Define a Supply Record○Update a Record Member○Exercise: Update a Record Member○Walk an Array of Records○Exercise: Walk an Array of Records○Pass a Record to a Function○Exercise: Pass a Record to a Function✦Module Quiz
○Demo: One Value in Shared Storage○Exercise: Record One Ticket Value○Demo: A Tag Tells You What Is Stored○Exercise: Read a Tagged Repair Ticket○Demo: Compare Union and Struct Storage○Exercise: Choose the Right Storage✦Module Quiz
○Demo: Read Bits with AND○Exercise: Check an Equipment Flag○Demo: Turn a Flag On with OR○Exercise: Mark a Kit Ready○Demo: Toggle and Clear Individual Flags○Exercise: Toggle a Warning Flag○Demo: Move a Bit into Position○Exercise: Build a Position Mask✦Module Quiz
○Include the Right Header○Exercise: Include the Right Header○Guard a Macro Default○Exercise: Guard a Macro Default○Demo: Include Code Only for Debug Builds○Exercise: Gate an Inventory Diagnostic○Demo: Parenthesize a Simple Macro○Exercise: Keep a Macro Calculation Grouped✦Module Quiz
○Name a Status with enum○Exercise: Name a Status with enum○Alias a Record Type with typedef○Exercise: Alias a Record Type with typedef✦Module Quiz
○Where the storage comes from○Demo: Request and Release an Array○Exercise: Store Three Repair Counts○Demo: Start Allocated Counters at Zero○Exercise: Start Station Counters at Zero○Allocate and Release Records○Exercise: Allocate and Release Records✦Module Quiz
○Print a Formatted Label○Exercise: Print a Formatted Label○Print Characters with putchar○Exercise: Print Characters with putchar○Format into a Bounded Buffer○Exercise: Format into a Bounded Buffer○Write a Line to stdout with fputs○Exercise: Write a Line to stdout with fputs●Input and Diagnostics in a Local Terminal✦Module Quiz
Input and Output Safely

Input and Diagnostics in a Local Terminal

At a local registration desk, a program could ask for a visitor's name. Input arrives through stdin; ordinary results go to stdout; diagnostics go to stderr. For example, fputs("No name read\n", stderr); writes a diagnostic. A terminal may show both output streams together, but they are separate.

getchar() returns the next input character as an int, or EOF at end of input or on error. Check for EOF before converting it to char. putchar() writes one character to stdout. For a bounded line, fgets(buffer, sizeof buffer, stdin) reserves space for the null terminator. Check for NULL before using the buffer. If a line exceeds the buffer, unread characters may remain; a full application must handle that case. Never use unbounded gets().

Try this in a local terminal only. Compile with gcc -std=c11 -Wall -Wextra -Werror main.c -o main, run ./main, type a short name, and press Enter. This is not a runnable browser block: the hosted runner may not accept interactive stdin or local file access.

c
#include <stdio.h>
int main(void) {
    char name[32];
    fputs("Name: ", stdout);
    if (fgets(name, sizeof name, stdin) == NULL) {
        fputs("No name read\n", stderr);
        return 1;
    }
    printf("Registered: %s", name);
    return 0;
}

For a short name, fgets retains the newline you typed, so printf does not add one. The runnable exercises here use fixed data; none require stdin or stderr capture.