CSCI 220

break statement

causes an exit from a loop and is available within the while, do while, for, and switch statements

exit(1)

causes the program to abort

%c

character format

%s

character string format

relational operator

comparison symbol showing a relationship between two expressions

Function Definition

consists of comments , a header, and a body

Hexadecimal to Binary

cover each hex digit in the number into its decimal equivalent

Binary to Hexidecimal

cover each nibble (4 bits) of binary number into its hex equivalent

implicit conversions

data types on the right side of an expression are converted to the data type on the left side

function prototype

declares the function so that the compiler knows about it, provides a complete description of the function interface. Provides the function return value, function name, and parameters

stdlib.h

defines a few mathematical functions in the standard library

#define directive

defines a macro constant name and value whose name is automatically replaced by the macro constant value through the program file. ex. #define KMS_PER_MILES 1.609

scope of an identifier

determines where that identifier can be referred to in the program code

if-esle statement

double alternative decision statement

binary (base 2)

each digit represents a unique power of two

%ld

long decimal

%o

octal format

"r" mode

opens the named file for reading only from the beginning of the file

"w" mode

opens the named file for writing from the beginning of the file (overwrites original file)

"a" mode

opens the named file for writing from the end of the file (does not overwrite original file)

putchar()

outputs a single character to a standard output (terminal window). arguments should be one individual character either variable or constant

file I/O statements

performed using getc() and putc(). each takes an extra argument which identifies the file pointer to be used for input or output

Examples of function

printf(), scanf(), isupper(), tolower()

fopen()

program must open a file before it can be accessed through this function. fopen() returns the required file pointer

Ternary operator

'?' is the only ternary operator in C, i.e. it requires 3 operands: the expression being tested, the two alternative outcome expressions

character size

1 byte (8 bits). A character string is n+1 bytes where n is the number of characters in the string.

3 steps of an algorithm

1. Algorithm must have a finite number of instructions or steps. 2. Each instruction is well defined (not ambiguous). 3. The algorithm eventually halts

Six steps to good programming habits

1. Analyze the problem. 2. Develop an algorithm. 3. Write code for the program. 4. Run the program. 5. Test the results. 6. Document the program

Steps to create a user-defined function

1. Declare the function, 2. Write the function definition, 3. Write the call(s) to the function

Precedence of operators

1. Highest 2. Unary 3. Multiplicative 4. Additive 5. Shift 6. Relational 7. Equality 8. Conditional 9. Assignment 10. Comma

file pointer

C communicated with files using a data type called a file pointer. a file pointer called fp is declared in a statement like: FILE *fp;

Decimal to Binary

Continually divide the number by two and record its remainder (0 or 1). The binary is the number recorded in reverse order

Decimal to Hexadecimal

Divide the number by 16 and store the remainder. print the remainders in reverse order

Compiler Directives

Handled by the C preprocessor as it makes its first pass through your program file

Unsigned/signed binary numbers

If a binary number is unsigned, use the algorithm for binary to decimal. If the number is signed and the leftmost digit is a 0, then use this same algorithm. If the number is signed and the leftmost digit is a 1 then take the two's complement and the use the algorithm and make the decimal you receive negative.

operations on mixed data types

If you perform binary operations on two different data types, the compiler will convert the data type that requires the fewer number of bits to the data type requires the greatest number of bits for storage

Binary to Decimal

Multiply each digit of the binary number by increasing powers of two and add the results

function included in math.h

Power Fnctns, Absolute Val Fnctns, Nearest Integer and Remainder Fnctns, Exponential and Logarithmic Functions, Trig Functions

topdown design

State the problem, subdivide the problem into major subtasks, divide subtasks into smaller tasks called modules, repeat process until each module is one that is easily solved and trivial to implement in C

assignment operator

assigns the value of the operand on the right hand side to the operator on the left hand side

loop control condition

a logical expression that evaluates to either true or false

putc(c, fp);

a macro which places the character value of c in the file pointed to by fp. It returns the int value of the character written. note that putchar(c) is a macro defined a putc(c, stdout). Function prototype: int putc(int c, FILE *fp);

c = getc(fp)

a macro which retrieves the next character from the file pointed to by fp. The value of the character is returned as an int. Function prototype: int getc(FILE *fp);

Function

a subprogram that carries out a particular task. Its purpose is to group together a related set of statements that performs some well-defined step in an algorithm.

Text File

a text file is a sequence of characters terminated by an end-of-file marker

Numeric escape code

allow any character to be expressed by writing that character as its octal (base 8) encoding in the target character set

decision statements

allow programs to follow different courses of action or execute different tasks depending on the data values

repetition statement

allows you to specify that an action is to be repeated while a certain condition remains true

variable

an object that can some different values during the execution of a program. Every variable has a name and value

switch statement

another multiple choice control structure. it can only be used in certain cases where only one variable is tested, the variable must be an integral type

fclose()

empties the buffer and breaks all connections to the indicated file. EOF is returned if fp is not associated with a file. If you don't close the file, the system will close it for you but it is always better to do it to make sure the data is properly saved

semantic error

errors in the meaning or implementation of the program

run-time error

errors that occur when the computer attempts to perform an illegal operation or instruction

syntactic error

erros in the programming language syntax

Logical operator evaluation

evaluated left to right and evaluation stops as soon as the truth of falsehood of the result is known

comma operator

evaluates the first subexpression and then the second

numerical data types

ex. int, double, float, char

initialization

first part of a for loop, it is run before the loop is entered

%f

floating point

nested for loop

for loop within a for loop

scanf()

function in the standard library which allows you to input values into a program from standard input (keyboard)

User defined header files

header files that you create that may define information specific to your program. The double quotes tell the C preprocessor that the included file is user defined instead of a C standard Library header file. C assumes the user define header is in the same directory as where the program is compiled unless otherwise specified

math.h

header that defines various mathematical functions in the math library. All functions in this library take double as an argument and return double as a result

%x

hexadecimal format

global scope

identifiers that are declared before the main () function. These can be referred to anywhere in the program code

local scope

identifiers that are declared within a specific function. They are only visible within that specific function. i.e. function parameters

%d

integer or decimal (base 10 format)

redirection request

puts the program's standard output into a file instead of the terminal

file modes

read, write, and append

Flow of program execution

refers to the order in which the C code is executed. Execution begins at the first statement in main() and statements are executed one after another from first to last

counter controlled loop

repeats a series of executable statements a specified number of times using a variable to count the number of loo iterations completed

floats/doubles

represent numbers that have a fractional component (double is a floating data type that uses double the storage). C guarantees that sizeof(float)<=sizeof(double)

integers (int)

represent whole numbers that do not have a fractional component

sizeof()

returns an integer that represents the number of bytes used to store an object on the host computer. C guarantees that sizeof(short)<=sizeof(int)<=sizeof(long)

getchar()

returns the next character form standard input (keyboard) and returns it as a function return value. If there is no more input then EOF is return instead

%e

scientific notation format

test

second part of the for loop, it tests the loop control variable and the loop is exited when the test is no longer true

do while loop

similar to the while loop except that the test occurs at the end of the loop body which guarantees that the loop is executed at least once before continuing

loop control variable

single variable in a loop control condition

Comments

statements that clarify the meaning and content of your program file

Stepwise refinement

subdivision of tasks

Hexadecimal to decimal

take the reverse order of the hexadecimal number and substitute the values for the letters. then multiply by increasing powers of 16 and add the results

Negative binary numbers

take the two's complement by flipping all bits and adding 1

Angle brackets '<>'

tell the C preprocessor the the included file is a C standard Library header file

accessing text files

text file is accessed via a pointer to a structure that is defined in the standard header file stdio.h as FILE

Calls to the function

the calls cause the function to execute and return values. There may be many calls with different arguments

explicit conversions

the cast operator converts (casts) the value of a variable into a type that is different from the original type of the variable

working directory

the directory where the program was run from

update

third part of the for loop. Typically a statement that is executed every time the loop body is completed, usually an increment or a decrement

increment/decrement

unary operators (require only one operand) adds one to its operand and subtracts one from its operand respectively

%u

unsigned decimal

%lu

unsigned long decimal format

sentinel value

used when we don't know when we want the loop to stop. it indicates "end of data entry". It is a user defined control variable that the user enters when they want the loop to end

decimal base 10

uses 10 digits to represent values

Hexidecimal

uses 16 digits to represent 16 base values

continue statement

utilize if you wan to go back to the top of the loop when something unexpected happens

constants

values that cannot be modified during the execution of a program (can be a number, character, or character string)

Identifiers

variable or function names that are referred to in the program code

nested if statement

whenever an if statement is texted within another if statement, put braces around the nested if statement.

for statement

works well where the number of iterations of the loop is known before the loop is entered