research topics in computational science. agenda survey overview
Post on 14-Jan-2016
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Research Topics in Computational Science
Agenda
• Survey Overview
Notes on the Survey:
• End on Time– I will try to end 10 min early for work & qus
• This isn’t too slow– Nobody said slow, but some said fast
• Upload Class Code– More time on my code (I will slow down)
• Go Quicker: with questions• Go Slower: with in class coding
Today’s Agenda
• Code with notes– practice for homework set
• Download the PPT to follow along with while coding
Indexing And Arrays
• In C we start counting at 0• The “1st” value is actually the “0th” value in C
Array Indeciesdouble x = {0.0, 3.14, …, 1.1, 2.7}
0.0
• x[0]
3.14
• x[1]
…
1.1
• x[n-2]
2.7
• x[n-1]
The computer needs to set aside memory, then the values can be placed in memory.
For an array of n elements we start at element 0 and access up to element n-1.
Arrays
• An array is a data object of a fixed size to hold many variables of the same type
• int[] a, b, c; // Will create 3 integer arrays• This doesn’t allocate memory for the array• a = new int[10];• Allocates memory for 10 ints in array a
• int[] a = {0,1}; //declare, allocate, assign values
Lists
• List<int> – Creates an int list
• List<double>– Creates a double list
• List<string>– creates a list of strings
• List<someType>– creates a list of the type
specified between <>
• We can create lists of any object
• We can have a list of buttons or images
List Functions
• x = myList[3];– gets the value at index 3 from the list
• myList.Add(3.14);– Adds the value 3.14 to the list
• myList.Remove(3.14);– removes first occurance of 3.14 from the list
• myList.RemoveAt(3);– removes the item myList[3]
c++, c--, ++c, --c
• Only used for “int”• c++ and ++c will add 1 to the
variable c– c++ will use c, THEN add 1– ++c will add 1 to c, then use it
• c-- and --c will subtract 1 from the variable c– c-- will use c, then subtract 1– --c will subtract 1, then use c
Example:c = 0;mbox(c++);//displays 0mbox(c);// displays 1mbox(++c);//displays 2
For Loop
• This will loop a specified number of times, AND increment a variable (usually i, j, or k)
• There is a standard loop that is used MOST of the time
• You can change as needed
For Code
for (int i=0; i<5; i++) { mbox(“Hello” + name[i]);}
• This will say hello to the first five names in the array “name”
• Start at i=0• Continue while i<5• At the end of every loop
do the operation i++
For Each Loop
• This will loop through each element of an array or list
• This can be very useful when we don’t know how many things are in our list/array
ForEach Code
int cider = 0;foreach(int age in ages){if(age<20) cider++;/* count the number of cider drinkers */}
• We have to declare the type, here it is an int
• We have to give a temp name, age is a clear name for this
• We have to give the name of our array/list
While Loop
• While loops can run forever!– Becareful of infinite loops
• These will run while a statement is true
While Loop Example
bool myval = 1;while( myVal < 100 ) { myVal = myVal * 2;}
• This will find the smallest power of 2 greater than 100.
• After each loop it checks the while
Do While Loop (aka do loop)
• This loop will ALWAYS execute one time• At the end of the loop it checks to see if it
should run again
Do While Loop
myVal = 200;do { myVal *= 2;} while (myVal < 100);
• This does the same thing as the last loop.
• Even though 200 will give a false value for “while” it will still do the loop one time
Switch Control
• Select based on matching input
• This is good when you have a lot of cases to be tested for.
Switch Code
switch( word ) { case “boy”: // do this break; case “girl”: // do this break; default: // do this break;}
• If the variable word is the same as “boy” it will do the first statement
• it will try every CASE until it finds one that matches or the end.
• Every case must have a break.
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