C++ Exam 2
Something within a while loop must eventually cause the condition to become false or a blank result
Infinite loop
This operator increments the value of its operand, then uses the value in context
Prefix increment
Whereas < is called a relational operator, x < y is called a(n)
Relational expression
If an OPEN file command fails in a program, what should you code?
Send an error message to the user and end or exit the program
Multiple relational expressions cannot be placed into the test condition of a for loop
True
When the increment operator precedes its operand, as in ++num1, the expression is in this mode.
prefix
What would you do to correct the following selection structure: switch (counter); { case 1 x=1 case=2 x=2 case=3 x=3 default: Cout << "invalid input"; }
switch (counter) { case 1 x=1; case=2 x=2; case=3 x=3; default: cout << "invalid input"; }
Write a program using a "while" statement with a number that starts at 3001 and repeatedly subtract 3 from that number until the number is negative. then print the number.
#include <iostream> using namespace std; int main () { int num = 3001; while( num > 0 ) { num = num - 3; } if (num < 0) { cout << num; } return 0; }
This operator represents the logical AND.
&&
These are operators that add and subtract 1 from their operands
++ and --
What is assigned to the variable a given the statement below with the following assumptions: x = 10, y = 7, and z, a, and b are all int variables. a = x >= y;
1
What is the output of the following segment of code if the value 4 is input by the user when asked to enter a number? int num; int total = 0; cout << "Enter a number from 1 to 10: "; cin >> num; switch (num) { case 1: case 2: total = 5; case 3: total = 10; case 4: total = total + 3; case 8: total = total + 6; default: total = total + 4; } cout << total << endl;
13
Look a the following statement while (x++ < 10) which operator is used first?
<
This operator is used in C++ to represent equality.
==
The while loop has two important parts: an expression that is tested for a true or false value and blank
A statement or block that is repeated as long as the expression is true
Input values should always be checked for:
Appropriate range Reasonableness Division by zero, if division is taking place ---All of these---
What 3 functions does an Operating System perform when an OPEN command for a file is issued for a program?
Assigns the file to your program Sets a pointer to the first record Allocates I/O buffer
Relational operators allow you to blank numbers
Compare
This is a variable that is regularly incremented or decremented every time a loop iterates
Counter
A while loop is somewhat limited because the counter can only be incremented by 1 each time through the loop
False
If the subexpression on the left side of the || operator is false, the expression on the right side will be false
False
The condition that is tested by a while loop must be enclosed in parenthesis and terminated by a semicolon
False
The default section is required in a switch statement
False
The following code correctly determines whether x contains a value in range of 0 through 100 if (x >= 0 && <= 100)
False
The increment and decrement operators can be used in mathematical expressions; however, they cannot be used in relational expressions
False
The scope of the variable declared in a for loop's initialization expression always extends beyond the body of a loop
False
What will be the output of the following code segment after the user enters 0 at the keyboard? int x = -1; cout << "Enter a 0 or a 1 from the keyboard: "; cin >> x; if (x) cout << "true" << endl; else cout << "false" << endl;
False
You may nest while and do while loops, but you may not nest for loops
False
You may not use the break and continue statements within the same set of nested loops
False
You may not use the break statement in a nested loop
False
This is a variable, usually a bool or an int, that signals when a condition exists.
Flag
This means to increase a value by one
Increment
What will the following segment of code output? score = 40; if (score > 95) cout << "Congratulations!\n"; cout << "That's a high score!\n"; cout << "This is a test question!" << endl;
That's a high score! This is a test question!
If you place a semicolon after the statement if (x < y)
The compiler will interpret the semicolon as a null statement.
What will the following segment of code output? int x = 5; if (x = 2) cout << "This is true!" << endl; else cout << "This is false!" << endl;
This is true! This is all folks!
A while loop's body can contain multiple statements, as long as they are enclosed in braces
True
An expression that has any value other than 0 is considered true by an if statement
True
An initialization expression may be omitted from the for loop if no initialization is required
True
Both of the following if statements perform the same operation if (sales > 10000) commissionRate = 0.15; if (sales > 10000) commissionRate = 0.15;
True
If the subexpression on the left side of an && operator is false, the expression on the right side will be false
True
The update expression of a for loop can contain more than one statement
True
You should be careful when using the quality operator to compare floating point values because of the potential roundoff errors
True
You may define a blank in the initialization expression of a for loop
Variable
When does the EOF condition arise when reading or accessing a file?
When you attempt to repass the last record
What will the following segment of code output? You can assume the user enters a grade of 90 from the keyboard. cout << "Enter a test score: "; cin >> test_score; if (test_score < 60); cout << "You failed the test!" << endl; if (test_score > 60) cout << "You passed the test!" << endl; else cout << "You need to study for the next test!";
You failed the test! You passed the test!
When a relational expression is false, it has a value
Zero
The statements in the body of a while loop may never be executed, whereas the statements in the body of a do-while loop will be executed:
at least ounce
Without this statement appearing in a switch construct, the program "falls through" all of the statements below the one with the matching case expression.
break
This statement may be used to stop a loop's current iteration and begin the next one
continue
The while loop contains an expression that is tested for a true or false value, and a statement or block that is repeated as long as the expression:
is true
This is a control structure that causes a statement or group of statements to repeat
loop
A loop that is inside another loop is called:
nested loop
If you place a semicolon after the test expression in a while loop, it is assumed to be a(n)
null statement
The do while loop is a ______ loop that is ideal in situations where you always want the loop to iterate at least once
post test
The while loop is this type of loop
pre-test
A for statement contains three expressions: initialization, test, and
update
Write a program for problem #5 using a "for" loop.
#include <iostream> using namespace std; int main() { for(int num=3001; num>0; num=num-3) { if(num>0) { num = num - 3; cout << num << endl; } } return 0; }
This operator takes an operand and reverses its truth or falsehood.
!
What is the output of the following code fragment? n = 1; while (n <= 5) cout << n << ' '; n++;
1 2 3 4 5
If you want to stop a loop before it goes through all of its iterations the break statement may be used
True
Write a nested conditional statement to execute the following logic: We receive a number from a user at the terminal. Check the number to make sure it is not zero. If it is zero, send an error message to the user and end the instruction. If the number is not zero, check to make sure the number is not negative. Send the user an error message if it is negative but otherwise divide this number into the second number entered by the user and print the answer back to the user.
#include <iostream> #include <iomanip> using namespace std; int main() { double number1, number2, newnum; cout << "Enter a number: "; cin >> number1; cout << "Enter a second number: "; cin >> number2; if (number1 == 0) { cout << "Error, you entered 0."; return 0; } if (number1 < 0) { cout << "Error, you entered a negative number."; return 0; } if (number1 >0) { newnum = number2 / number1; cout << fixed << setprecision(2) << newnum; } }
Is the following nested loop structure correct? If not, how would you correct it? int i, count; while (count < 100) { for (i=1;<100;i++) { cout << "\n I is now " << in << endl; cout << "Inner loop execution " << endl; } cout "Outer loop execution " << endl; }
#include <iostream> using namespace std; int main() { int i, count; count=0; while (count < 100) { for (int i=1; 100>=i; i++) { cout << "\n I is now " << i << endl; cout << "Inner loop execution " << endl; cout << "Outer loop execution " << endl; count=count-1; } } }
After execution of the following code, what will be the value of input_value if the value 0 is entered at the keyboard at run time? cin >> input_value; if (input_value > 5) { input_value = input_value + 5; else if (input_value > 2) input_value = input_value + 10; else input_value = input_value + 15;
15
Assuming x is 5, y is 6, and z is 8, which of the following is false? 1. x == 5; 2. 7 <= (x + 2); 3. z <= 4; 4. (1 + x) != y; 5. z >= 8; 6. x >= 0; 7. x <= (y * 2)
3 and 4 are false.
In a for statement, this expression is executed only once
Initialization
Name and describe the 4 components of a loop
Initialize the LCV Test the LCV Loop body Update/Modify LCV
Will the following instruction execute correctly? If not, how would you correct it? cin >> type; cin temp; if(type = 'C') celsius = (5.0/9.0) * (temp-32.0); cout<<"\n Temeperature in Celcius is" << celsius << end; else farhen= (9.0/5.0)*temp+32.0; cout<<"\n Temeperature in Fahrenheit is"<<fahren<<end;
No, missing iostream and iostring header missing several { } brackets. Also, instead of "=" you need "==" cin >> type; cin temp; if(type == 'C') celsius = (5.0/9.0) * (temp-32.0); cout<<"\n Temeperature in Celcius is" << celsius << end; else farhen= (9.0/5.0)*temp+32.0; cout<<"\n Temeperature in Fahrenheit is <<fahren<<end;
This statement lets the value of a variable or expression determine where the program will branch to
Switch
As a rule of style when writing an if statement, you should indent the conditionally executed statement
True
When an if statement is placed within the conditionally-executed code of another if statement, this is known as:
nesting
