COMP10120

C Preprocessor Lines

Lines beginning with # that are processed before compilation;

#include directive

Tells the preprocessor to include the contents of a header file (like stdio.h) in the program;

stdio.h purpose

Header file containing information for standard input/output library functions like printf and scanf;

Function definition in C

C programs contain one or more functions, one of which must be main;

main function purpose

The function where a C program starts executing;

int before main

Keyword indicating that main returns an integer (whole number) value;

void in main parameters

Indicates that main does not receive any information/parameters;

printf function

Instructs the computer to print a string of characters on the screen;

Character string terms

Also called a message or a literal, marked by quotation marks;

Statement terminator in C

The semicolon (;) that ends each statement;

Escape character

The backslash (\) used to create special character sequences;

\n escape sequence

Newline - causes the cursor to position to the beginning of the next line;

\\ escape sequence

Prints a single backslash character;

\" escape sequence

Prints a double quote character within a string;

Standard library function

Functions like printf and scanf that are not part of C but are in the standard library;

Linker purpose

Locates library functions and inserts proper calls to them in the object program;

Executable

The complete, linked program ready to be executed;

Binary operators

Operators that require two operands (like + in 6 + 9);

* operator

Asterisk used for multiplication in C;

% operator

Percent sign denoting the remainder operator (modulo);

Integer division result

Yields an integer result (e.g., 8/5 = 1, 18/4 = 4);

Remainder operator usage

Only use % with integer operands to get the remainder after division;

Remainder operator example

8 % 5 yields 3, and 18 % 4 yields 2;

Parentheses in expressions

Used for grouping subexpressions to control order of operations (e.g., a * (b + c));

Operator precedence order

1. Parentheses/Brackets 2. Multiplication, division, remainder (left to right) 3. Addition, subtraction (left to right) 4. Assignment (=) evaluated last;

Variable definition

Locations in memory where values can be stored for use by a program;

int type

Specifies variables that store whole numbers (integers) like 9, -16, 0, 30675;

Valid identifier rules

Series of letters, digits, and underscores (_) that does not begin with a digit;

C case sensitivity

C treats uppercase and lowercase letters as different (e.g., sum ≠ Sum ≠ SUM);

scanf function purpose

Obtains input value from the user (usually from keyboard);

scanf arguments

Two arguments: format control string (like "%d") and address of variable (like &integer1);

%d conversion specifier

Indicates that the data should be a decimal integer in scanf or printf;

& address operator

Ampersand followed by variable name, tells scanf the memory location where the variable is stored;

Format control string

First argument in printf containing text and conversion specifiers (like "Sum is %d\n");

Multiple input reading

Can read multiple values with one scanf: scanf("%d%d%d", &a, &b, &c);

Variable components

Every variable has a name, a type, and a value;

Memory location placement

When scanf executes, the entered value is placed into the memory location assigned to that variable name;

Destructive memory write

When a value is placed in a memory location, it replaces the previous value;

Assignment statement

Calculates a result and assigns it to a variable using the = operator (e.g., sum = integer1 + integer2);

Assignment operator nature

The = operator is a binary operator because it has two operands;