edX: - HarvardX: CS50x3 Introduction to Computer Science - week 2

More about  functions and data types are discussed in the lecture while at the end, is the tragic story about the Patriot missile which was caused by a  floating point arithmetic error. 




Some short notes here on the lecture:-

can omit curly braces when using one line of code
ssl - encrytpion
regulations about cs50
functions
abstraction - encapsulates
int - returns an integer
implementing get positive int for error checking
int n in the proper braces
prototype
scope - local vs global
data types - char,int, etc
char - 1 byte or 8 bits - 256 total values
int - 4 bytes -  4 billion values
float 4 bytes, double 8 bytes, long long  8 bytes
overflow - 0 comes after 255 for 8 bit values
problems related to float

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edX: - HarvardX: CS50x3 Introduction to Computer Science - week 1 Continue

Right at the end is the touching story of Saroo Brierly which  is going to be made into a film soon.





Some short notes here on the lecture:-

make - make object code
./hello
printf is in stdio.h
main - default entry point
paranthesis - holds what is used in printf
double quotes - surround phrase
\n- newline
;   -   finishing a statement
make - finding the file and convert to object code
clang - compiler
clang hello.c - ls to list contents of directory - a.out
mv a.out hello  and then -lcs50
in stdio.h   more to printf
escape sequences
%i is a placeholder for integer
types of variables - float, int , char
in cs50 library - string and bool - Getstring etc
condition  - if condition   { do this }
boolean expression   -  if condtion  and/or another condtion is true needs && and ||
switches - like if else but use cases
loops  -  for, do while
variables need to be defined
functions
a program to do addition with  int x=Getint();
condition-0.c  -  if, else  at first but could not detect zero so if , else if and else used


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edX: - HarvardX: CS50x3 Introduction to Computer Science - week 1

A  history of Paul Allen and Bill Gates and their path to programming the Altair 8800 is read out by two students.  String variable is introduced in this lecture.







Some short notes here on the lecture:-

source code
compiler
object code  0 and 1

while (true) - can run forever
for loop - iterate from 0 to 10
variable - store something
counter - counts forever
boolean expressions  eg    if x>y
condition - compares

compiler - eg gcc
standard environment linux  - a hypervisor
cs50 appliance - gedit
make - triggers the compiler - saves 0 1and1 in a file called hello
./hello runs 
\n is actually new line
string s   %s
printf is part of stdio.h
cs50.h library has functions
GetString
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edX: - CornellX: ENGRI1210x The Computing Technology Inside Your Smartphone

This is another digital course I have been trying out. Seems  interesting so far.  Topics are:-

• Describe how a smartphone processor works
• Explain computer system design from binary information to programming
• Design a small working computer
• Describe common techniques used to make computers fast

edX: - HarvardX: CS50x3 Introduction to Computer Science - week 0 continued

There is an amusing example of how programs work with peanut butter jelly sandwich in this lecture.



Some short notes here on the lecture:-

variable - container
loop   - for
condition  - if else

scratch program
statement - eg say hello world,  wait for one second, play sound
boolean expression - eg.  >,  true or false, touching mouse pointer
condition block - if else if else
loops - repeat
variable n
mltithreading
multicolored bulb and binary bulbs

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