C Introduction

How it works

C describes operations on values and storage. A compiler translates source into a program for a particular target. You will use that control to build small field-survey tools: counting observations, checking readings and saving a report. This is hosted C, where a runtime starts main and supplies standard streams; a microcontroller can have a different startup contract. You need no previous programming, but you should be comfortable saving a plain-text file and opening a terminal. Start with one file so you can connect every displayed result to an instruction.

Run it locally

Use a hosted C17 compiler in a separate lab folder. The command assumes a driver named cc; substitute gcc, clang or zig cc as appropriate. C does not currently run in Bhylu’s browser playground. Apache, PHP and MySQL are not needed for these C programs.

cc -std=c17 -Wall -Wextra -Wpedantic -Werror intro.c -o lesson

On Windows, use -o lesson.exe and run .\lesson.exe in PowerShell. On Unix-like systems run ./lesson. Math-library linking differs by toolchain; GCC on many Unix systems needs -lm after the source.

Download the complete C source. File-writing labs must run in an empty private directory, away from existing reports.

Example

#include <stdio.h>

int main(void) {
    int markers = 6;
    int spare = 2;
    printf("Survey markers: %d\n", markers + spare);
    return 0;
}

Expected result

Survey markers: 8

The include supplies declarations for the standard output library. main is the entry point of this hosted program. The two objects hold counts; the expression adds their values before printf formats the result. A successful return from main becomes an exit status for the caller. This example uses no database, web server or browser.