Syntax/Code in C

if branch

A branch taken only if an expression is true.

branch

A sequence of statements only executed under a certain condition.

printf();

Format and print data

%d

Integer format character - used to indicate the placement of a variable in text

/* Notes */

Multi-line comment (can be used for single line)

%%

Prints the '%' character.

printf("%d", variableName);

Prints the variable value of an integer

pow(x, y);

Returns the value of x to the power of y

srand()

Seeds the random number generator

// Notes

Sets off a single line comment, does not need to be ended off with anything

reserved word/keyword

Word (or symbol) that has a meaning already defined in the language, CANNOT be used as an identifier

for loop

a loop that iterates a specified number of times

loop

a program construct that repeatedly executes the loop's statements (known as the loop body) while the loop's expression is true; when false, execution proceeds past the loop

while loop

a programming construct used to repeat a set of commands (loop) as long as (while) a boolean condition is true

floating point number (ex. 1.0, 89.2, -0.9993)

a real number with a decimal portion

character literal

a single character that appears in single quotes (') in a program

array

a single variable storing an ordered list of items (known as elements), each being directly accessible

break;

a statement within a loop that causes an immediate exit of the loop

continue;

a statement within a loop that causes the program to jump to the loop condition check

+

addition operator

strcat(userCaption, "string");

adds the specified string onto the end of the first string

#include <time.h>

allows use of time()

character array (ex. variableName[##])

an array whose components are of the type char

identifier

an attribute (or group of attributes) whose value is associated with one and only one entity instance must be a sequence of letters, numbers, and underscores, and START with a letter or underscore

=

assigns values from right side operands to left side operand, variable to be assigned goes on the LEFT

++i

because i = i + 1 is so common in programs, the programming language provides a shorthand version (pre-increment operator)

--i

because i = i - 1 is so common in programs, the programming language provides a shorthand version (decrement operator)

int main() {}

beginning of function named main

arrayName[#]

calls on a specific index of an array

userString[#]

calls upon a specific character index in a string note the first character in the string has an index of 0

arrayName[#] = ##

changes the specified index of the array to the given value

null character

character '\0' that marks the end of a string in C

(type)variableName

converts a variable to another type, specified by the contents of the parentheses

tolower('A');

converts the specified character to lowercase, does not modify an argument - only returns a value

toupper('a');

converts the specified character to uppercase, does not modify an argument - only returns a value

strlcpy(str1, str2, n)

copies the first n characters of str2 into str1

int arrayName[R][C]

creates a 2-D array with R rows and C columns

long long variableName;

creates a 64-bit variable instead of a 32-bit one, for numbers greater than 2B that generate an overflow

const int/double VARIABLE_NAME;

declares a constant variable, will produce an error if future code attempts to modify it

int arrayName[# of elements];

declares an array with a specified number of elements within brackets

int variable;

declares an integer variable

/

division operator NOTE: when dividing an integers, outputs a truncated integer with no decimal places

iteration

each time through the loop's statements

#include <stlib.h>

enables use of the rand() function

\

escape sequence - used to display certain characters such as " ' and \ (ex. \' \" \\)

!=

evaluates to true if the left and right sides are NOT equal

if (condition) { expression; } else if (condition) { expression; } else { expression; }

format for if-else if-else branches

>

greater than operator

>=

greater than or equal to operator

%lf

indicates a double within a string literal

scanf("%d", &(arrayName[#]));

inputs an integer value into the given array at the specified index #

<

less than operator

<=

less than or equal to operator

incrementing the variable

means adding a value to it. (Specifically, the term often means to add 1 to a variable.)

%

modulus operator, outputs the remainder of integer division

switch (variableName) { case 1: code; break; case 2: code; break; default: code; break; }

more clearly represent multi-branch behavior involving a variable being compared to constant values

*

multiplication operator

\n

new line

\0

null character in string, at the end of a string

%.#lf (where # is a natural number)

outputs # number of digits after the decimal point in a double calculation

strlen(variableName)

outputs the number of characters in a string

order of precedence for operators

parentheses logical not (!) arithmetic operators relational operators equality/inequality operators logical AND logical OR

\t

places a tab within a string literal

%lld

prints a long long int within a string literal

%c

prints a single ASCII character

%s

prints a string

#include <ctype.h>

provides access for several functions to work with characters

{index0, index1, ..., indexN}

used to initialize an array with specific values

M_PI

value of pi

return 0;

terminates the main() function, needed at the end of the code

string literal

text in double quotes

#include <math.h>

the math library with several math constants, such as pi

a && b

true when BOTH of its operads are true

a || b

true when at least one of its operands are true

!a

true when its single operand is false

#include <stdio.h>

tells the compiler to include information about the standard input/output library

strcpy(str1, str2)

Copy the contents of str2 into str1

fabs(x);

Takes the absolute value of x, returns the number as a positive float

binary

The ??? number system is base 2, using only bits 0 and 1.

==

The equality operator (sometimes read: "equal equal") is used to compare two values, and returns a Boolean (true/false). Avoid confusion with the assignment operator "=", Note: string and float comparisons sometimes do not behave as expected

if-else branch

The first branch is taken if an expression is true, else the other branch is taken.

comparing floats/doubles

rather than comparing for equality, compare if they are 'close enough' ex. fabs(x - y) < 0.0001;

userString[#] = 'x'

replaces the specified index with the specified character

#include <string.h>

required to be included to use strcpy

rand() % N

restricts the outputs to integer values less than N but greater than 0

strcmp(string1, string2)

returns 0 if two strings are equal returns a non-zero value if strings are unequal (negative if string1 is less than string2, positive if string1 is greater than string2)

rand()

returns a random integer from 0 to RAND_MAX (usually machine-dependent)

time(0)

returns the number of seconds since 1/1/1970

isdigit('5');

returns true if the specified character is a digit 0-9

isalpha('x');

returns true if the specified character is a letter in the alphabet

isspace(' ');

returns true if the specified character is whitespace, including newlines

#.##e# (where #s serve as digits, no limit on the number, and the exponent can be + or -)

scientific notation written in C

compound operators - +=, -=, *=, /=, %=

shorthand way to update a variable

double variable;

stores a floating-point number

char variableName;

stores a single character, surrounded in single quotes when assigned to a variable (ex. 'm' or '*')

for (initialExpression; conditionExpression; updateExpression) { // Loop body } ex) for (int i = 0, i < 5; i = i + 1) { //loop contents }

structure of a for loop (note: the looping variable can be declared within the loop)

-

subtraction or negation operator

while (expression) { //loop body }

syntax of a while loop, statements inside brackets execute as long as the expression evaluates to true; if false, the code runs after the brackets

scanf("%s", variableName);

takes input of a string, NOTE that no '&' is required

sqrt(number);

takes the square root of the value (can be an expression/variable) inside parentheses