Updated: 09/12/2023 by Computer Hope

C may refer to any of the following:

C: prompt

1. C describes the C: drive or the first hard drive on IBM-compatible computers.

C programming book

2. The C programming language was developed by Dennis Ritchie and Brian Kernighan at Bell Labs in 1972 from an almost unknown language named B. The first major software written in C was the Unix operating system, and for many years, C was considered to be inextricably linked with Unix. Pictured is The C Programming Language book by Kernighan and Ritchie, also sometimes called the bible in the computer field.

C program example

Below is an example of a C program that prints "Hello World!" after it's been compiled. If you need a free C compiler, consider GCC (GNU Compiler Collection).

#include <stdio.h>

int main()
 printf("Hello World!\n");

3. With measurements, C is an abbreviation for Celsius. As the SI-derived symbol C is short for coulomb, when lowercase, c is of centi.

4. The C button on calculators is short for "clear" and clears all last numbers and totals. Calculators with this key may also have a CE button that only clears the last entered number. For example, if several numbers are entered before the number you're entering now, press the CE button only to clear the current number without deleting any prior numbers. To clear everything, press the C button.

5. C is a keyboard key used with the keyboard shortcuts Alt+C, Command+C, and Ctrl+C.

6. Shorthand and chat slang for see or sea. For example, someone may say "ICU" in chat as a short method of typing "I see you."

7. With Microsoft Excel and other spreadsheet programs, "C" is the third column of a spreadsheet. To reference the first cell in the column, you'd use "C1."

8. In Adobe Photoshop, C is a shortcut to select the Crop tool. Pressing Shift+C cycles through related tools, including the Perspective Crop tool, Slice tool, and Slice Select tool.

9. In the phonetic alphabet, "C" is often pronounced as "Charlie."

10. As a Roman numeral, "C" is 100.

11. C is the third letter in the English alphabet. The letter "C" comes after "B" and is followed by the letter "D." To create a capitalized "C," press Shift and C at the same time.

On U.S. QWERTY keyboards, the "C" key is on the bottom row, to the right of the "X" and left of the "V" key. See our keyboard page for a visual example of all keyboard keys.


If the "C" key is not working on the keyboard, see: Some keys on my computer keyboard aren't working.


In ASCII (American Standard Code for Information Interchange), the uppercase "C" is "067" in decimal (01000011 in binary). The lowercase "c" is "099" in decimal (01100011 in binary).


Doing the Alt code Alt+67 creates a capital "C" and Alt+99 creates a lowercase "c" character.


The number 2 on a phone keypad creates an "C" on a US phone.

C++, Celsius, Computer abbreviations, GCC, High-level language, Letter, Procedural language, Programming languages, Programming terms, .SEA