$ cd ~/cs170/labs $ mkdir lab1 $ cd lab1
It's time to learn a new language! Python is a great language, especially for learning programming concepts and for efficiency of creating programs. C++ might seem a little bulky in comparison. But that bulk brings some benefits with it. Some errors that Python would not find until executing the program can be found earlier, etc. Today we will begin with some simple C++ programs.
A lot of the general concepts we covered last semester still apply here. When you see something that seems like it should use a loop, we're going to use a loop. If you see something that seems like it should use a conditional, you will use a conditional. This is an activity that we very easily could have given you last semester. Let's practice our new C++ skills by writing a program to allow your professor to be very lazy!
In a file called GradeAverage.cc, create a program that will prompt the user to enter a number n, followed by n numbers representing their grades for a course. Your program should then print the users grade average.
$ g++ -c GradeAverage.cc $ g++ -o grade GradeAverage.o $ ./grade How many grades? 3 100 90 80 Your grade average is: 90 $ ./grade How many grades? 2 100 99 Your grade average is: 99.5
You can use cin to read an integer from the
terminal. It may seem obvious, but you need to declare your
variable before you read into it.
int someVariable; cin >> someVariable;
You can use a while loop to accomplish the repetition necessary in this program. The syntax for a while loop is very similar to that in Python. However, the parenthesis around the condition are not optional! In addition, the curly braces dictate what the body of the loop is. These are not optional either.
while (some condition) {
body of the loop
}
cout is the mechanism used to
print things to the terminal. It can print basically any
datatype, but different datatypes should be separated by
a <<.
cout << "The answer to life, the universe, and everything? " << 42 << endl;
Modify the above program so that it can process multiple students at once. The format of the input will need to change to accomplish this.
$ ./grades
Number of Students? 2
Number of Grades? 2
Scotty
60
50
Scotty's average: 55
Bouchard
100
99
Bouchard's average: 99.5
Even datastructures we are aware of from Python at least have analogues in C++. For example, Strings. To use a String, we must include a separate library. However, this extra library gives a lot of extra power to the language.
In a file called Palindromes.cc, create a program that will prompt the user to enter a string. Your program should output whether the input string is a palindrome or not. Recall that a palindrome is a string that is read the same forwards and backwards.
$ ./palindrome hello hello is not a palindrome $ ./palindrome bob bob is a palindrome
cin can be used to read in any
datatype. it decides what it is reading based on the type
of the variable it is being read into! It's really useful
that way!
string someVariable; cin >> someVariable;
A for loop is longer than the for loop in Python. It is essentially encoding a special form of a while loop.
for(loop variable declaration; condition; increment) {
body of the loop
}
So, a for loop that executes 10 times would be:
for(int i; i < 10; i++) {
body of the loop
}
A pangram is a sentence which contains all of the letters of the English alphabet. Create an additional program which will read in an entire sentence, and will check to see if it is a pangram.
You will need to use
the getline
function to read an entire line from the terminal.