Lec8 - Lecture 8: The if Statement PIC 10A Todd Wittman if...

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1 Lecture 8: The if Statement PIC 10A Todd Wittman if Statement Example r Programs should be able to adapt to user input and branch in different directions. r A popular 1960s war protest slogan was "Don't trust anyone over 30." r How do we check if we can trust someone? int age; cout << "Enter your age: "; cin >> age; if (age < 31) cout << "I trust you.\n"; if (age > 30) cout << "I DON'T trust you.\n";
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2 What is a boolean? r A boolean statement is a true / false statement. c (2<3) is a true statement c (2>3) is a false statement r Later we’ll learn about boolean ( bool ) variables, which take on only true or false values. Could also do 1(T) / 0(F). bool my_boolean = (2 < 3); bool my_boolean = true; bool my_boolean = 1; r Named after logician George Boole (1815-1864). All the same. Sec 4.1 : The if statement r An if statement will execute the statements that follow only if the boolean condition in parentheses is TRUE. if ( statement is TRUE ) { **STATEMENTS** } int x = 2; int x = 4; if (x < 3) { if (x < 3) { cout << "hi"; cout << "hi"; } } Outputs "hi" Outputs nothing nada zip Notice the indentation of the closing }. Lines up with the if statement.
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3 The braces { } r The braces { } tell us what statements to run if the statement is true. r Without the braces, only the first line following the if statement is executed. int x = 2; int x = 2; if (x > 3) { if ( x > 3) cout << "My "; cout << "My"; cout << "precious!"; cout << "precious"; } Outputs nothing. Outputs “precious” r On the right, would have been better not to indent
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Lec8 - Lecture 8: The if Statement PIC 10A Todd Wittman if...

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