/\P5C I6O

DeMorgans Law for boolean expressions

!(p||q) = (!p && !q) !(p&&q) = (!p||!q)

code for digitalWrite

#define LED 0 //... #define ON1 OFF 0 //... digitalWrite(LED,ON);

to read a string format specifier: %s no & in variable call

#define LINEMAX 8 char line [LINEMAX]; ex. scanf ("%s",line); testing → line = testing ex. scanf ("%4s",line); testing → line = test ex. scanf ("%s",line); two words → line = two careful as user may enter more text than can be stored in the string

when using PI ..

#define PI acos(-1.0) -> more accurate

code for digitalRead

#define SWITCH0 //... int switch_status; //... switch_status=digitalRead(SWITCH);

String Functions for normal arrays, we'd have to write size as a parameter in fncs, but for strings with the \0, this is not required

#include <string.h> strlen(s) returns length of s (not incl \0) strcopy(s,t) copies string t to string s

printf( "Error: "%s", "data.txt");

%s for imputing strings of characters, like file name

string constants ex. "sensor.txt" since its a string, the last element is assumed to be \0

' single quote=character constant " double quote = string constant -the null character has n ASCII integer eq of 0

void scanline(char str[ ], int size) this fnc reads a line from standard input and stops if \n, EOF, or index size-1 reached

'if' statement in while loop checks if value returned from getchar() = EOF or \n. if true, break. str[len++]=(char)c //c = retval, (char)=cast note: len++ here increments starting at 0 since ++ coming after means the value BEFORE incrementation is used.

ex. cargo.dat = weights of cargo. write program for total weight # unknown

(start) → [totWeight=0]→<more data in file?> →/input(file):weights/→[totWeight+=weights] for <more data in file?> use fscanf since it returns # data read from file code: while (fscanf(inputFile,"%lf",&itemWeight==1) fscanf will return -1 or 0(in case where data cant be read as double)

when var first declared, contains garbage value

--

scope of a variable defn

-block of code {} within which that variable is declared → defines which part of code has access to that var -variables are said to be *local* to that scope

global variable defn

-declared outside body of any fncs -has *global scope* accessible by all fncs in the program -hard to debug since all fncs use it

lifetime of local vars -timeframe in which memory is allocated

-have *automatic* storage class by default ie. memory automatically allocated to these cars when corresponding fnc is called and de-allocated when fnc call ends (return 0; ex. )

2. array indexing

-initially each index has garbage val -access indiv elements within an array by using indexes

benefits of using fncs

-prob decomp reflected in code -each fnc can be developed/tested indiv by diff ppl → efficient -easy to debug bc each fnc small part -abstraction makes program easy to read -reduces length of code

steps for solving function problems

1) algorithm 2) modular structure chart 3) write main code 4) write functions

good programming style

1) opening comments 2) clear variable names c) CAPITALIZED symbolic constants d) body of function made to look easy to see start/end e) blank lines btwn parts of code doing distinct tasks f) include units ex. m/s when prompting for input g) output (ex. range) labelled so user knows that it is

file IO and functions

1. define symbolic constant ex. INPUTFILE "runScores.txt" 2. declarations: FILE* inFile; (FILE* can be seen as "int" or "double") 3. inFile=fopen(INPUTFILE,"r"); 4. calling in fnc: use inFile, outFile instead of symbolic constants

4 steps for reading from a file

1. open file 2. verify file opened correctly 3. read files' data 4. close file

Writing data to a file (instead of screen) 4 steps

1. open file for writing 2. verify its opened correctly 3. write data to file 4. close file

double num = 1.0/10.0 + 1.0/10.0 + 1.0/10.0 cant do tests of equality (num ==0.3) for floating point values (double) because...

1/10 cant expressed as a floating point value in computer ∴ make boolean to see if num is 'close enough' → (fabs(num-0.3)<0.0001?) fabs = absolute value function

binary -> dec

1011₂ = 1(2³)+1(2²)+0(2¹)+1(2⁰) =13₁₀

dec -> binary

14 / 2 R0 7 / 2 R1 3 / 2 R1 1 / 2 R1 14₁₀ = 1110₂

"distance" btwn 2 arrays algorithm

2 loops outer one controlling which index in arrA to compare with inner loop actually calculating the distance inner - min distance of all indexes of arrB to one index in arrA outer - min of these mins

dec -> hexadec

250/16 R10 15/ 16 R15 =FA

hexadec -> dec

7A,50,E6 each pair - 1 btye ( 8 bits) data A - 10, B-11,C-12, D-13,E-14, F-15 3E = 3(16¹)+E(16⁰) =62₁₀

double analogRead( int analogChannelNumber) for when values vary widely, not just 0 or 1 discrete signals - digital analog signals - continuous values

CD player - accepts digital ata from CD drive and converts it to analog signal to be used by speakers

1. open file for writing

FILE*outputFile; before int main (void); outputFile=fopen("results.txt","w"); after variable declarations NOTE: if file alr contains data, it will be erased outputFile=fopen("results.txt","a") to 'append' and add new info after old

arrays cannot be target of an assignment

NOT ALLOWED: arr2=arr1 data2=data2+data1

arrays cant be return type of a fnc

NOT ALLOWED: int [] getValues(void);

2 switches , switch 0 and 1

S0 on → LED 0 on S1 on → LED 1 on both on → LED 2 on

rmbr to define

TRUE FALSE I/O CHANNELS SWITCH_ON SWITCH_OFF NUM_DISPLAYS SPACE_CHAR DELAY_TIME SIMULATOR -need to assign a variable to assign to status of switches for digitalRead, analogRead

What is necessary if you want to read a bunch of integers from a file?

That they're all diff lines, ie. seperated by white space ex. blank / new line If integers are separated by comma, need to call "%d," in fscanf =: the way you input data into file is important when you want to read it

some functions in standard C library and process of abstraction

abstraction: calls a fnc without understanding how it works ex. double sin(double angle); double pow (double base, double exponent); if a fnc doesnt take any parameters, it's 'void' ex. int main (void) returns an integer and takes no parameters

ex. of using nested loops for incremental coding problem: prompts user for size -> prints out * triangle ex. 3: * ** ***

algorithm: row#=#stars outer loop (row <= size?) → # rows inner loop (star <= row?) → # stars variables: row, star, size

character array

an array in which the indiv elements are character ( are type char) ex. char filename[4]={'t','e','s','t'};

for functions that return an array

array returned is a parameter, just write "return;" at the end -everytime array indexes need swapping, use variable 'temp'

strings : character array in which last array element is null character '\0' in order to identify last element of the array , similar to \n, a special character

benefit: don need to worry about size of array bc last element always a null character and can easily be found

post test loop - use when want loop to be ran at least once, ex. playing a game b4 quitting

boolean test comes after body of loop so loop executed at least once do{ /*body*/ } while (Boolean); notice the semicolon, not there in pretest loop

use early return and break statements to end functions early. ...

by checking (after variable declarations) if the inputs passed even make sense in terms of the function. for example, if length in writeNumber==0, it doesnt make sense to continue

how to convert a char from lower case to uppercase

c=c-'a'+'A' -'a' gives u index + 'A' gives u the uppercase number with that index

fscanf in reading a file doesnt always have to return 1 , can return data per line

can also make it return 1 var: while (fscanf( inFile,"%*d %lf %*lf ..",&next);

QUIZ: what will happen if SIZE=3 int index; int data []={4,1,8}; intdata2[SIZE]; for(index=SIZE;index>=0;index--) data2[SIZE-1-index]=data[index];

cant tell bc first run: data2[-1]=data[3] both indexes are out of the allowed range

double

capable of storing floating point values up to 15 dec places

"what is the value of this variable from the fnc "

check if it explicitly returns something. if it doesnt, the value is what it was when it was initialized RMBR a fnc can only return one value in main, rmbr to assign a variable to the return val of a fnc

lookup tables : use an array to display digits 0-9 so digits[0]=byte of data to display 0 replaces 'runtime computation' with simpler array 'indexing operation'

const int digits[ ] ={252, 96, 218, 242, 102, 185, 190, 224, 254 246}

ex. int countZerios(int arr[],int num); ... int numZeros=countZeros(data,count);

data and arr will both refer to same array even if diff names in actual and formal parameters

if want to copy input from keyboard to string, need to..

declare a temporary string for holding user-entered data. cant sprintf the data directly

#include <stdio.h>

declares printf scanf

Sleep( ) <Windows.h> (uppercase) takes parameters in milliseconds

define ONE_SECOND 1000

setupDAQ( int setupNum ), continueSuperLoop( void) used for init. and control of flow of program

digitalRead( int ChannelNumber ), digitalWrite( int ChannelNumber, int value ) used for I/O from/to digital devices digital = only reads binary vals 0,1 define TRUE 1 FALSE 0 at top of all programs

dont forget "print \n"

dont make the ++ or -- mistake when making a picture

implicit casting - taking dbl value 91.2 and assigning it to int value iData

double dData = 45.6; int iData; iData=dData * 2.0; in the end, iData=91 since its an int value got casted from dbl to int

3. array initialization

double data[]={5.2,3.8,7.2}; -not nessecary to specify size of array

code for max of 2 vals fnc - this fnc cant be used in isolation. 'return' statement terminates execution of fnc - only one return val possible

double maximum (double num1, double num2){ double maximum; if (num1>num2) maxVal=num1; else maxVal=num2; return maxVal; }

1. array declaration

double strain [10 000]; declares an array of 10 000 variables of type double data [0]=5.2; assigns 5.2 to 0th index of array

boolean exp

eval to true or false <=, >=, !=, ==, &&, ||, !(unary)

event vs counter controlled loops

event: executes until some event occurs (ex. user enters 1) -dont know how many times it will run → do while/while counter: know how many times it will run beforehand (ex. print all elements of an array) → for loops

character arrays (not string) -a 'char' variable limited to range [-128, 127] and when used in fncs, they represent printable characters

ex. char somecharacter=104; //no "" printf("%c,somecharacter); will print 'h' instead of memorizing chart, can just write 'a','z'

you CAN have an empty for loop

ex. int stringLength(char str[ ]){ int length=0; for(length=0;str[length]!='\0';length++){ } return length; }

you can put input from scanf or fscanf directly into array instead of declaring another var and making arr[index]=var

ex. while (count<MAX_ATHLETES && fscanf (inFile, "%d %lf %lf %lf", &ids[count], &scores[count][0], &scores [count][1], & scores [count][2])==4){

declaring: a character string can be initialized using string constants(no commas) or character constants(letters seperated by commas)

ex. char filename[ ]="sensor.txt"; the size (no need specified) is 11=10+1 for null character -note: no { }

sprintf - to write to a string sprintf (destString, formatString, var1...varN); purpose: to create a new string, destString, from a number of vars you already have the same string variable, destString, cant equal var 1....varN. ie. shouldnt be in both source & destination sprintf same as printf except for destString parameter at start

ex. int mynum; char filename[100]; //100 is more than enough, the unfilled spaces = garbage printf("Enter a number"); scanf("%d," &mynum); sprintf(filename, "myfile-%d",mynum); printf("file name is %s,filename); for input=30 → filename is myfile 30. the 2nd param in sprintf is the MSG youre writing to the string

to print out a string format specifier: %s no brackets [ ] in variable call

ex. printf("%10s \n %10i \n",label, pressure); 10 = field width

4. close file

fclose(inputFile); put at end of function or end of conditional block

4. close file writing

fclose(outputFile); at end of body of conditional block or function

ex. maximum fnc takes larger of 2 values -takes 2 'couble' vals as parameters and returns larger one

fnc prototype: >double maximum (double num1, double num2)< goes before int main (void) after hashtags

2. check if file opens correctly

fopen returns "NULL" if file fails after inputFile=fopen... write: if(inputFile !=NULL){

*for* loops - another way of writing while loops ex. for(index=SIZE;index>=0;index--)

for (init; boolExpr; post){body} init: initialization statement executed once per run of loop if Bool true→body→post if still true→again when false→exit loop

format specifiers: %d, %f for int %lf for double for scanf

for printf: %X.Yf with sometimes (+/-) before X Y= # decimal places (default = 6) X= width of field (default=just enough or default # decimal places) (-X) → aligned on left side; otherwise, aligned to right (spaces first) (+X) → sign of # always printed ex. a=4.52366 %-6.1f → 4 . 5 _ _ _ (. takes up one space) %6.2f → _ _ 4 . 5 2

code for looping through strings

for(i=0; str[i]!='\0'; i++)

infinite loops

forgetting to modify variable in loop so boolean always true or error in boolean exp.

3.write data to file

fprintf (filePointer, formatString, var1, ... varN); formatString → like "%lf" for double

you can put ret val of fnc (and array vals)` directly as variable in (f)scanf

fprintf(outFile, "%d "lf "lf \n",ids[row], rowMax(row,scores)) where rowMax is a fnc

3. read files data

fscanf: fscanf (filePointer, formaString, &var1, ... &varN) like scanf but with extra file pointer parameter fscanf returns an integer representing # of pieces of data read from file

operator precedence

highest to lowest !, ++, --, unary +, unary - / * % binary +, binary - <, >, <=, >= ==, != && || =,+=,*=.....

4. array processing

how to print to screen all elements of an array of given size: int data []= {3, 8, 2, 5, -1, 9}; int index=0; while (index<SIZE){ printf("%d",data[index]); index++; }

code for (nested) branching

if (Boolean) { /*true block*/ } else if { /*false block 1*/ } else { /*false block 2*/ } braces: used to define start/end, optional when block is single statement

code to set up daq

if (setupDAQ(setupNum)==TRUE){ //code } else printf("Error")

when passing parameters to a fnc , do not inc TYPE of parameter in the CALL incl it when DEFINING the fnc (header, prototype)

if parameter is an array, do not put []

2. check file opened correctly

if(outputFile != NULL) { ... } after opening the file

parameter passing mechanism

in main: 1.waterCosts=maximum(unitsUsed*WATER,MIN); ... function header: 2. double maximum(double num1,double num2) 1.when fnc is called →"actual parameters" 2.when fnc defined → "formal parameters"

how to check if file with name user entered already exists

in variable declarations, initialize file = NULL: FILE* file = NULL; -this way, if the file with the same name DNE, it will remain NULL as it will fail to open

in most simple nested loop, with count++, what is value of count when it endss?

inner loop runs * outer loop runs times

if output file cannot be opened,

input file should be closed

2D arrays

int data [3][2] → 3x2 array int data [] [3] = {{3,1,5},{4,0,2}};

copying an array - use for loop

int index; for (index=0;index<SIZE;index++) arr2[index]=arr1[index];

1. open file

int main (void) { FILE* inputFile; variables declared inputFile=fopen("data.txt","r"); inputFile is the variable pointing to the file we want to open "r" for read

<stdio.h> fncs for printing strings

int printf (const char* format,.. ) int fprintf (FILE*file, const char* format); int sprintf (char* str, const char* format, ...); char* = character array string const char * = unchanging array (message to be printed in this case )

to sum elements of row of 2D array to sum rows - increment cols to sum cols - increment rows

int rowNum, colNum; double sum; for(rowNum=0; rowNum<RSIZE;rowNum++){ sum=0.0; for (colNum=0;colNum<CSIZE;colNum++) { sum+=powerOutput[rowNum][colNum];} printf("% %,rowNum+1,sum); note: this doesnt sum entire array bc sum reset to 0 everytime loop runs

<stdio.h> fncs for reading stings

int scanf (const char* format, ...); int fscanf(FILE* file, const char* format, ... ); int sscanf (const char* str, const char* format,...);

explicit casting - does not convert sum from int -> dbl, converts VALUE of sum to dbl for purposes of this calc only

int sum; int count; double avg; sum=123 count=10 sum/count = 12 double avg so 12.0 which is WRONG => need casting : average = (double) sum/count

data type : int

int: stores ints from -2bill to 2 bill unsigned int: 0-4bill

use *trace tables* to keep track of value of variables and value of booleans controlling the loop

line # | variable | boolean(t/f) when reach false -> cont. with rest of code

char word [ ] = "mouse"; word[0] = 'h'; //single quotation marks word[5] = 's'; printString(word); whats printed?

no null character so fnc will continue to print until it encouters 0 (# for NUL) or until memory runs out ie. houseadjflkajdfkl

for workFunction, one time tasks, like initializations/declarations occur before/after superLoop

note for arrays: int name[100]={1} → 1 0 0 0 0 .... -can declare an array explicitly, or use a loop if the entries follow a pattern -an arrray occupies a 'continuous location' in memory. the size than an array occupies is (#elements)(size of element type)

% modulous (remainder) operator

only for (+) num/ (+) num ex. 12 % 3 = 0 5 % 12 = 5

function interface specification - t ensure fncs can work tgt; specifies ins/outs

possible in/out: -fr keyboard to screen -input parameters output return values

what is the output from the following code segment: int count = 0; do { printf("%d",count); count--; } while (count>0); printf(%d",count);

post test so loop executed at least once => 0 is printed printf outside the loop => -1 printed => 0 -1

pretest looping

pretest: boolean tested before loop; may never run while (Boolean) { /*body loop */ }

passing arrays as parameters

primitive type (int, char, double) → pass-by-value array → pass-by-address ∴array is not copied when its passed, the formal and actual parameters refer to the *same array*

when simulator number not defined,

prompt user for setupNum

temperature sensor

resistor whos resistance ( and ∴ voltage) varies with temperature (K) and voltage(V) is linearly α to temperature T=V (T₀/V₀) where T₀,V₀ is a reference point

photocell

resistor whos resistance changes depending on amnt of ambient light. ↑ light → resistance ↓

returns pseudo random number btwn 1 & max

return rand () % max +1 without the +1, it would be btwn 0 and (max-1)

array defn

seq of vars stored one after another in memory each with index starting at 0

flowchart shapes

start/end - circle decision (boolean) - diamond compute - rectangle input/output - parallelogram

identifier rules

starts with letter or _ all characters are letters, numbers, _ cant start with number

data type: char

stores a singlel character ex. char midInitial ='A'; need quotation marks

the role if \0 is to ...

terminate the string. if removed, it wouuld no longer be a valid C string and the contents of the array would be garbage. The results would be unpredictable after it prints whats given

if var is declared in a loop, what is the scope

the body of the loop, not accessible outside loop

char str [10] = " ";

this initializes all entries to NUL (0)

DAQ- data acquisition

to acquire data, ex. temp uses sensors, user input, devices -processes data in computer with C programs, excel -DAQ also has display so we can interface it to other devices

abstraction defn

to hide unimportant details and focus on inputs/outputs only

if turning LEDS on/off in a pattern , ex, one after another, only need to define LED 0, bc the other ones can be operated using a loop

to round numbers: int A = double B +0.5

how to order an array in ascending order

two 'for' loops nested for looping the array, one starting at i=0, one starting at j=i+1 if (num[i] > num[j]) → swich the nums by using placeholder variable i = num on left j= num on right

algorithms defn

unambiguous seq of steps for solving problem (flowchart)

Increment/Decrement operators

unary operators ++i; prefix i++; postfix used alone → no diff used with other operators: ++a = value AFTER inc/dec a++ = value BEFORE inc/dec

8 bit binary numbers range 0-255 since all LEDS on = 255 in binary

use 8 bit binary numbers to write to 7 segment displays "0b########"

to print + + + + (space in btwn)..

use modulous to print space every ___ characters. ex. count %2==0 will print - - - count%3==0 will print -- -- --

functions - put documentation at opening and before calling new function. fnc doc indicates purpose and intereface

used for modular programs ex. for nested loops, each loop can be its own function -use flowcharts to rep. relationship btwn modules in the program. ex [main]-[printRow] means that main will be called first and main will use printRow in it -main codes for outer loop (#rows) printRow codes for inner loop (#stars)

Analog Sensor Potentiometer (POTs) rotary potentiometers: compares angle on the two segment arm, determines angle btwn 2 objects connected through the POT

variable resistor acting like analog input device -resistor linearly changes with the angle, thus the voltage (output) changes as well. ---Then, angles can be later derived from measured voltage

controlLeds( ) with no if turns LED 0,1,2 on/off depending on state of switches

void controlLeds(void){ int switch0=digitalRead(SWITCH0); int switch1=digitalRead(SWITCH1); digitalWrite(LED0,switch0&&!switch1); } note that it checks status in the variable declaration and the param in digitalWrite has no ==ON or ==OFF

displayWrite( ) bc digitalWrite impractical for writing to 7 segment displays since we would need 8 fnc calls per display. 1 dec byte = 8 binary bits

void displayWrite(int data, int position); assumes we have several LEDs grouped tgt in a row data - val to be written to 7 segment display (binary, dec 0-255, hex) position- which LED display is writtten to Left → right = 7→0

returning data from fnc stored in ararays here, nVals copies val of SIZE from main (not shown)

void getValues(int data[],int nVals){ int index; int next; printf("enter %d int vals:",nVals); for (index=0;index<nVals;index++){ scanf("%d",&next); data [index]=next; } }

function prototype - beginning of code same as function header except prototype ends with ;

void printRow (int row); declares that fnc printRow takes parameter of type int and has no return value

printString(...) prints an arbitrary character string in sequence

void printString(char message[ ]){ int i; for(i=0; message[i]!='\0',i++){ printf("%c",message[i]); } } note: length not needed as a param

remember to append strings with \0 at end

void stringCopy (char dest[],char srs[]){ int length=0; for(length=0; src[length]!='\0',length++){ dest[length]=src[length];} dest[length]='\0'

sometimes superloop will call many fncs that take a long time. btwn such long calls, the daq may have alr shut down or the use quit. therefore, check continueSuperLoop( ) within body of loop and exit loop early if needed

void workFunction (void) { while (continueSuperLoop( )==TRUE){ long Fncs( ); *if (!continueSuperLoop( )){ break;}* OR if(continueSuperLoop( )){ longFnc2( )}; can use break or if statements

writeNumber function including length and offset, assuming there is no MAX_DISPLAYS value how to extract digit: digit = number%10 how to truncate number: number = number/10

void writeNumber( int number, int length, int offset){ const int DIGITS_TABLE[]=<252,...} const int SPACE_CHAR 0 int pos=offset; int digit=0; if (length==0){ return; } do{ digit=number%10; number=number/10; displayWrite(DIGITS_TABLE[digit],pos); pos++; } while (pos<offset+length &&number!=0); while (pos<offset+length){ displayWrite(SPACE_CHAR,pos); pos++; } }

scope of parameters is also the body of the corresponding fnc

when a variable/parameters is local - can only be accessed within scope and nowhere else in program

pass-by-value mechanism

when fnc is called, val of actual parameters copied and used to initialize corresponding formal parameters

short circuit evaluation

when part of boolean doesnt need to be evaluated to evaluate overall expression ex. a=0, x=1 (a!=0) && (x==1/a) 2nd condition DNE but since 1st is flase, whole thing is false

you can use system ("PAUSE") in functions other than main, just anytime u want to pause before continuing

whenever using 8 screen display for general purposes, include the >const int DIGITS_TABLE[10]<

any of the binary arithmetic operations can be assignment operator to make a 'compound assignment' operator

x=x[ ]y → x[ ]=y

when manipulating strings, define : char c=message[i] to shorten code and to modify c, not the original string

you can make char strings of diff lines: char text []=".../n" "...\n" ; note the multiple quotation marks.

MT1: int x = 3, y=2, z=0; if(x++<4){ if (++y>2) z=x+y printf("z is %d \n",z); printf("y is %d \n",y); } else printf("x is %d \n",x); what does it print

z is 7 y is 3 since the ++ are both executed after the booleans execute. the before/after only applies while inside the boolean

the scanf family of fncs use white space to seperate tokens, so not useful for reading expressions containing spaces

∴ use int getchar(void) which reads characters one by one until the end of an input, such as \n or End-Of-File (EOF) character -return type 'int; accounts for special EOF character, ∴ need to CAST value to (char) when appending to output. -spaces are counted as characters in getchar ( ) while (c != '\n' && c != EOF){ line[len++] = (char)c; c = getchar(); } line[len] = '\0';