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2. What is a preprocessor directive?
2. An example of a preprocessor directive is #include The preprocessor copies code found in the header file iostream into the program.
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3. What does a compiler do?
3. The compiler translates C++ into machine code.
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4. At what statement does execution begin?
4. Execution begins at main.
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3. Why don’t comments increase the program size when the program runs?
3. comments are removed by the compiler
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3. Indicate if the following are valid variable names a) char
no: is a key word
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3. Indicate if the following are valid variable names b) 4thTest
no: can't start with a number
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3. Indicate if the following are valid variable names c) test#1
no: can't use special characters
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3. Indicate if the following are valid variable names d)overDueAmountThisMonthToDate
yes
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3. Indicate if the following are valid variable namese) test one
no: can not use spaces
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5. What values are initially found in the variables when declare?
garbage
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How many bytes is an int?
4
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how many bytes is a double?
8
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how many bytes is a string?
32
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how many bytes is a char?
1
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1. Write the statement that will declare a constant called PI initializing it to 3.414
const double PI=3.14;
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char code[25]={‘a’,’b’,’c’}; What value is stored in the last element?
a space
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Given int numbers[6]={4,3}; a) Draw the array.
[4,3,0,0,0,0]
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Given int numbers[6]={4,3}; b) What is the length of the array?
2
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Given int numbers[6]={4,3}; c) What is the size of the array?
6
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Given int numbers[6]={4,3}; d) What is the value of numbers[1]?
3
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Given int numbers[6]={4,3}; e) What is wrong with the statement cin>>numbers[6];
outside array
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Given int numbers[6]={4,3}; f) Write the statement that will add 2 to the first element in the array.
numbers[0]+=2
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int grades[8];
what is grade[0]=
garbage
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int numb[3];
numb[0]=5;
what is numb[1]=
garbage
-
int numb[3]={5};
what is numb[1]=
0
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how to end a loop with Ctrl+z?
- how do you clear the input buffer for a string entry after an int or double entry?
- cin.ignore(80,'n');
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2. show the values in the following arrays: a) int numb[5];
garbage, size=5
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2. show the values in the following arrays: b) int value[5]={40,30,30};
{40,30,30,0,0} size=5
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2. show the values in the following arrays:c) int numb[]={1,3,4,5};
{1,3,4,5} size =4(auto)
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2. show the values in the following arrays: d) string names[5]={ "J. Doe", "P. Smith" };
{ "J. Doe", "P. Smith",,, }
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2. show the values in the following arrays:e) char code[3]={ '1'};
{ '1',' ',' '}
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2. show the values in the following arrays:f) double width[]={1.9,3.9,4.9,5.0};
{1.9,3.9,4.9,5.0}
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what happens with for(;;)
infinite loop
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for (int ctr = 0; ctr<5; ctr++) //if declare ctr in for loop it can’t be used after loop T/F
T
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for (int ctr = 0; ctr<5; ctr++)
cout << ctr << endl;
cout << ctr << endl; //is okay? T/F
F
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for (int ctr = 0; ctr<5; ctr++)
cout << ctr << endl; //is okay? T/F
T, as long as ctr is not used outside the loop
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cout<<"Enter a number between 1 and 100 code:";
- cin>>numb;
- while (cin.fail()||numb<0||numb>1000)
- {
- cin.clear();
- cin.ignore(80,'n');
- cout<<"re-enter";
- cin >> num
- }
- cin.clear(80,'n') //in cin for text later
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Validate a product code.
- string productCode;
- cout << "enter a product code";
- while (productCode.length() == 0)
- {
- cout << "You did not enter a product code." << endl;
- cout << "Enter a product code: ";
- getline(cin, productCode);
- }
-
how to open a file.
- ofstream fout("products.dat");
- if (!fout.is_open())
- {
- cout << "The file products.dat could not open - need to fix" << endl;
- system("pause");
- exit(666);
- }
- how to send file to console
- system("type products.dat");
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beginning of file:
- #include <iostream>
- #include <string>
- #include <iomanip>
- #include <fstream>
- using namespace std
-
code for decimals:
fout << fixed << setprecision(2); // or cout
-
cout << "Enter a product code (or ctrl Z to end): ";
- getline(cin, productCode);
- while (!cin.eof())
- {...}
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