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CS31 You Lu CS31-1K TA. Hello World! Variable Out of the Range You input 8888888888, but it outputs another different number.

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Presentation on theme: "CS31 You Lu CS31-1K TA. Hello World! Variable Out of the Range You input 8888888888, but it outputs another different number."— Presentation transcript:

1 CS31 You Lu CS31-1K TA

2 Hello World!

3 Variable

4 Out of the Range You input , but it outputs another different number.

5 I/O cin >> cout <<

6 Input one word or string cin>>s; //can only input one word, e.g., only my first name. getline(cin, s); //can input the whole string, e.g., my first and last name

7 cin.ignore(10000, '\n') Use cin.ignore(10000, '\n') after reading a number if the next input will be of a string (using getline)

8 Arithmatic Division: 5/2=2; 5.0/2=2.5 – as long as one of the number is a “double” we have a “double” division. Mod: 5%2=1 (remainder) Casting: – int a = 2.5 a = ? 2 – (double)5/2 = ? 2.5 – (double) (5/2) = ? 2

9

10 Visual Studio 2010 Check the output of compiler to see if there is any warning or error every time.

11 iostream precision Default is 6 digits If “double a = ”; “cout << a” will only display Here you can use “cout.precision(9)” to set the output as 9 digits. See the example below.

12 iostream precision Be more careful to use “cout”

13 header file #include //standard built-in libraries #include “ccc_time.h” //user-defined libraries

14 if … if (condition) statement; condition: non-zero value means true; zero value means false;

15 another example

16 if…else… if (expression) statement; else statement; Nested if statement: if() { if() {…} else {…} } else if() { } else { }

17 Boolean expression Greater than or equal: “>=“ Less than or equal: “<=” Equal: “==” Not equal: “!=” Logic expression: – AND: && – OR: || – NOT: !

18 priority Arithmetic operator > relational operator 10 > 1+2 ↔ 10 > (1+2) “ logic operator cout << “true AND false is ” << (true && false);

19 priority highest! > >= < <= == != && lowest||

20 while loop while (expression) { statement; } do{ statement; } while (expression)

21 example

22 for loop for (initialization; condition; increment) { statement; } infinite loop: for(;;) { }

23

24 “continue” skip the current round loop, go to the next round loop for(…) { code 1; code 2; continue; code 3; }

25 example

26 “break” stop the current loop and get out of the loop. for (…) { code 1; code 2; break; code 3; } code 4

27 example

28 “goto” goto and “lable” must be in the same function. lable: goto [lable];

29 another example Jump out from a deep nested loop for(…) { for(…) { while(…) { if(…) goto stop; … } stop: cout << “Error in program. \n”; //”break” can only jump out from only one loop

30 Online reference Some websites are really helpful for you to learn C++, like More detailed reference: Microsoft MSDN library – us/vstudio/hh us/vstudio/hh – us/library/cscc687y(v=vs.80).aspx us/library/cscc687y(v=vs.80).aspx – us/library/3bstk3k5.aspx us/library/3bstk3k5.aspx

31 Look up “rand()”

32 My webpage for CS31 1K


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