C++ How to call an if statement loop? - c++

C++ code where a user enters 2 integers, then the program outputs how many numbers were multiples of 3 between those integers, including both numbers, and how many numbers were divisible by 5.
Here is my code. I think I am not calling the if statements correctly. Maybe I need a switch?
#include <iostream>
#include <cmath>
using namespace std;
int main() {
int numb1, numb2;
int sentinel;
int counter = 0;
int mult3 = 0;
int mult5 = 0;
cout << "Enter an integer:";
cin >> numb1;
cout << "Enter another integer:";
cin >> numb2;
cout << endl;
sentinel = (abs(numb2-numb1)+1);
if(numb1 % 3 == 0 && counter <= sentinel) {
mult3++;
numb1++;
counter++;
}
else {
numb1++;
counter++;
}
cout << endl;
counter = 0;
if(numb1 % 5 == 0 && counter <= sentinel) {
mult5++;
numb1++;
}
else {
numb1++;
counter++;
}
cout << endl;
cout << mult3 << " " << "numbers are divisible by 3 in between your entered integers." << endl;
cout << mult5 << " " << "numbers are divisible by 5 in between your entered integers.";
cout << endl;
return 0;
}

A short version for your code is given below. Checkout the while loop(not ran, just from top of my head).
#include <iostream>
#include <cmath>
using namespace std;
int main() {
int numb1, numb2;
int sentinel;
int counter = 0;
int mult3 = 0;
int mult5 = 0;
cout << "Enter an integer:";
cin >> numb1;
cout << "Enter another integer:";
cin >> numb2;
cout << endl;
while(numb1 <= numb2){
mult3 += (numb1%3)==0?1:0; // (numb1%3)?0:1
mult5 += (numb1%5)==0?1:0;
++counter;
++numb1;
}
cout << endl;
cout << mult3 << " " << "numbers are divisible by 3 in between your entered integers." << endl;
cout << mult5 << " " << "numbers are divisible by 5 in between your entered integers.";
cout << endl;
return 0;
}

You're not looping it at all, so this will only execute once.
while(counter < sentinel)
{
//run your tests and increment the appropriate variables if the numbers are divisible by 3 or 5
counter++;
}
start by evaluating the lowest of the 2 entered numbers + counter % 3 == 0

I got it. I had to use 3 separate while loops. One for <, one for >, and one for =. When I just had a <= and >=, the first loop would feed into the second. I took out the sentinel and the counter thanks to Avezan's help. Thanks everyone.

Related

Only negative numbers adding correctly

So I'm trying to write a program that will read in ten whole numbers and outputs the sum of all numbers greater than zero, the sum of all numbers less than zero,
and the sum of all numbers, whether positive, negative, or zero.
Currently only the total sum and negative sum is adding correctly. My positive sum is always 1 or 0. Any tips to get me in the right direction would help.
Current Code:
#include <iostream>
using namespace std;
int main()
{
int N = 0;
int sum = 0;
int positiveSum = 0;
int negativeSum = 0;
cout << "Number 1" << endl;
cin >> N;
cout << "Number 2" << endl;
cin >> N;
cout << "Number 3" << endl;
cin >> N;
cout << "Number 4" << endl;
cin >> N;
cout << "Number 5" << endl;
cin >> N;
cout << "Number 6" << endl;
cin >> N;
cout << "Number 7" << endl;
cin >> N;
cout << "Number 8" << endl;
cin >> N;
cout << "Number 9" << endl;
cin >> N;
cout << "Number 10" << endl;
cin >> N;
for(int i=0;i<10;i++)
{
if (N >= 0 )
{
positiveSum += N;
}
else
{
negativeSum += N;
}
}
sum = positiveSum + negativeSum;
cout << "The positive sum is= " << positiveSum << endl;
cout << "the negative sum is= " << negativeSum << endl;
cout << "The total sum is= " << sum << endl;
return 0;
}
After entering all Ns and when entring to the loop, you have only the last N. because after assigning the first number to N you don't process the value but you assigning the next value to N again after asking the user to enter it and so on. Use something like the following
#include <iostream>
int main()
{
int N = 0;
int sum = 0;
int positiveSum = 0;
int negativeSum = 0;
for(int i=0;i<10;i++)
{
std::cout << "Number "<<i + 1<< std::endl;
std::cin >> N;
if (N >= 0 )
{
positiveSum += N;
}
else
{
negativeSum += N;
}
}
sum = positiveSum + negativeSum;
std::cout << "The positive sum is= " << positiveSum << std::endl;
std::cout << "the negative sum is= " << negativeSum << std::endl;
std::cout << "The total sum is= " << sum << std::endl;
return 0;
}
And see Why is "using namespace std;" considered bad practice?

Program hangs and does not loop

I am a beginner in c++. I wrote a program to separate the digits in an integer entered and display them and their sum. However, when the loop repeats, the program hangs even though it compiled perfectly. I tried a '... while' loop and a while loop but the problem persists. What should I do to have it repeat (ask user for next integer, calculate and display the results) without problems? Any help will be appreciated.
//Preprocessor directives
#include <iostream>
#include <cmath>
//Standard library
using namespace std;
//enter function main
int main()
{
int num;
int digit;
int sum = 0;
int pwr = 0;
cout << "Enter an integer: " << endl;
cin >> num;
cout << endl;
while (num != 0 )
{
//while loop to ask user to enter another number
cout << "The integer you entered is: " << num << endl;
cout << "The digits of " << num << " are: " << endl;
if (num < 0)
num = -num;
//find the highest number of 10 that divides the number
while (num / static_cast<int>(pow(10.0, pwr)) >= 10)
pwr++;
while (num > 0)
{
digit = num / static_cast<int>(pow(10.0, pwr));
cout << digit << " ";
sum = sum + digit;
num = num % static_cast<int>(pow(10.0, pwr));
pwr--;
}
if (pwr != -1) //Either num is 0 or there are trailing zeros in num
while (pwr != -1)
{
cout << 0 << " ";
pwr--;
}
cout << endl;
cout << "The sum of the digits = " << sum << endl;
while (num != 0);
cout << "Enter another integer: " << endl;
cin >> num;
cout << endl;
}
return 0;
}
//Preprocessor directives
#include <iostream>
#include <cmath>
//Standard library
using namespace std;
//enter function main
int main()
{
while (true )
{
//reset initial values every loop
int num;
int digit;
int sum = 0;
int pwr = 0;
cout << "Enter an integer: " << endl;
cin >> num;
cout << endl;
//same exit condition
if (num == 0)
break;
//while loop to ask user to enter another number
cout << "The integer you entered is: " << num << endl;
cout << "The digits of " << num << " are: " << endl;
if (num < 0)
num = -num;
//find the highest number of 10 that divides the number
while (num / static_cast<int>(pow(10.0, pwr)) >= 10)
pwr++;
while (num > 0)
{
digit = num / static_cast<int>(pow(10.0, pwr));
cout << digit << " ";
sum = sum + digit;
num = num % static_cast<int>(pow(10.0, pwr));
pwr--;
}
if (pwr != -1) //Either num is 0 or there are trailing zeros in num
while (pwr != -1)
{
cout << 0 << " ";
pwr--;
}
cout << endl;
cout << "The sum of the digits = " << sum << endl;
//extraneous
/*while (num != 0);
cout << "Enter another integer: " << endl;
cin >> num;
cout << endl;*/
}
return 0;
}
I think you should use vector to store the digits... also the logic inside should be a bit smaller (see note 1), (note that I didn't test for negatives, you may use abs from cmath)
#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
//Standard library
using namespace std;
//enter function main
int main()
{
int num;
std::vector<int> digits;
int sum = 0;
int pwr = 0;
cout << "Enter an integer: " << endl;
cin >> num;
cout << endl;
while (num) {
while (num) {
int temp = num % 10;
digits.push_back(temp);
sum += temp;
num /= 10;
}
std::reverse(digits.begin(), digits.end());
cout << sum << endl;
for(auto & a : digits)
{
cout << a << " ";
}
cout << endl;
cout << "Enter another integer: " << endl;
cin >> num;
cout << endl;
}
return 0;
}
note 1:
while (num) {
int temp = num % 10;
sum += temp;
num /= 10;
}

Issue with C++ code

I was trying to figure out this task, but so far have been unsuccessful. I think I understand the logic behind it, I just don’t know how to nest loops so it works (if that makes sense). I would very much appreciate your help!
Task:
"Create an application in which a user enters full numbers until they enter number 0 (zero). The application should print out how many even numbers have been entered, how many odd numbers, sum of even numbers and sum of odd numbers, and total sum of numbers."
my code so far:
#include <iostream>
using namespace std;
void main() {
do {
int input1;
cout << "Type in a number";
cin >> input1;
} while (input1 != 0);
cout << "Type in a number";
cin >> input1;
if (input1 % 2 == 0)
{
int even = 0;
while (input1 % 2 == 0 )
cout << even;
even++;
}
else
{
int odd = 0;
while (odd != 0)
{
cout << odd;
odd++;
}
}
}
system("pause");
}
Note: I did not try to do the third part of the task, since the second one won't work :/ I figured out first part, and I did it with do while loop. Thanks again.
Try this:
int oddCount = 0;
int evenCount = 0;
int oddSum = 0;
int evenSum = 0;
int in;
do
{
std::cout << "Type in a number:";
std::cin >> in;
if (0 == in)
break;
if ( in % 2 == 0 )
{
evenCount++;
evenSum += in;
}
else
{
oddCount++;
oddSum += in;
}
} while ( true );
std::cout << "Odd count: " << oddCount << std::endl;
std::cout << "Even count: " << evenCount << std::endl;
std::cout << "Odd sum: " << oddSum << std::endl;
std::cout << "Even sum: " << evenSum << std::endl;
std::cout << "Total sum: " << oddSum + evenSum << std::endl;
Take a look at this piece of code:
#include <iostream>
using namespace std;
int main() {
int input;
int total_sum = 0, odd_sum = 0, even_sum = 0;
int odd_count = 0, even_count = 0;
do {
cout << "Type in a number: ";
cin >> input;
total_sum += input;
if (input % 2 == 0)
{
even_count++;
even_sum += input;
}
else
{
odd_count++;
odd_sum += input;
}
} while (input != 0);
cout << "Total Sum: " << total_sum << endl;
cout << "Even sum: " << even_sum << endl;
cout << "Odd sum: " << odd_sum << endl;
cout << "Even Count: " << even_count << endl;
cout << "Odd Count: " << odd_count << endl;
return 0;
}
See how input is declared outside of the loop. if it was inside it, then you essentially create it each time you enter the loop. that would be fine if you did not want to use its values outside of the loop (like in the loops condition).
Also, notice that the values you need to calculate can be updated within that same loop.

How do you make a counter to count the number of even and odd numbers entered by user?

I have this code so far that is supposed to keep asking the user for a number until they type 0. Then the program will tell the user how many odds and evens they typed. I cannot get the latter function to work correctly. Any tips? I am a beginner, so please no advanced ways to solve this :D
#include <iostream>
using namespace std;
int main ()
{
int n;
int myCounter1, myCounter2;
cout << "Odds and Evens\n\n" << endl;
do
{
cout << "Please enter an integer: ";
cin >> n;
myCounter1 = 0;
myCounter2 = 0;
if (n%2 == 0)
{
myCounter1++;
}
else
{
myCounter2++;
}
}
while (n!=0);
cout << "You entered " << myCounter1 << " even numbers, and " << myCounter2 << "odd numbers " << endl;
return 0;
}
A couple things:
Code indentation (or lack thereof) makes this really hard to read. Indentation is not only cosmetic, but can help in understanding code.
You are setting the counter variables to zero each time the loop runs. Declare them outside of the loop so they retain their values.
The else clause of the if statement has erroneous syntax. Use a simple else instead, as there are only two cases for the parity of n.
When the user types 0 to exit the loop, it too is counted as an even integer. Add a condition in the if statement to account for this.
Applying these changes yields this code:
int n;
int myCounter1 = 0, myCounter2 = 0;
cout << "Odds and Evens\n\n" << endl;
do {
cout << "Please enter an integer: ";
cin >> n;
if (n%2 == 0 && n != 0)
{
myCounter1++;
}
else
{
myCounter2++;
}
} while (n!=0);
cout << "You entered " << myCounter1 << " even numbers, and " << myCounter2 << "odd numbers " << endl;
This
else n == 0
{
myCounter2++;
}
should be
else
{
myCounter2++;
}
Honestly, I don't even know why it didn't grab your attention, since it can't compile.
Also, you shouldn't set the counters to zero in the loop. So
int myCounter1, myCounter2;
cout << "Odds and Evens\n\n" << endl;
do
{
cout << "Please enter an integer: ";
cin >> n;
myCounter1 = 0;
myCounter2 = 0;
should be
int myCounter1=0, myCounter2=0;
cout << "Odds and Evens\n\n" << endl;
do
{
cout << "Please enter an integer: ";
cin >> n;
And, finally, since you probably shouldn't count the 0 as one of the integers entered...
cout << "You entered " << myCounter1-1 << " even numbers, and " << myCounter2 << " odd numbers " << endl;
You have 2 bugs and 1 syntax error.
line:else n == 0 should be simply else
The 2 bugs are related to your counters:
1) You have to exclude the 0 input from the counters.
2) Every time you are reading a number your are setting them (the counters) to zero, which means that you will always ending with zero and one.
Here it is for anyone interested:
include
using namespace std;
int main ()
{
int n;
int myCounter1 = 0;
int myCounter2 = 0;
cout << "Odds and Evens\n\n" << endl;
do
{
cout << "Please enter an integer: ";
cin >> n;
if (n%2 == 0)
{
myCounter1++;
}
else
{
myCounter2++;
}
}
while (n!=0);
cout << "You entered " << myCounter2 << " odd numbers, and " << myCounter1-1 << " even numbers " << endl;
return 0;
}

Making my do while loop neater by removing repeating code

Hi here is my question.
Write a program that uses a do-while statement. It reads in an integer
n from the keyboard. If n is not in the range 1 to 10 it makes an audible
“beep” and asks for another integer. If n is in the correct range, it writes
out “You have input n” and then exits.
Here is my answer.
#include <iostream>
#include <Windows.h>
using namespace std;
void main()
{
int number = 0;
do
{
cout << "Enter an integer." << endl;
cin >> number;
if (!(number >= 1 && number <= 10))
{
Beep(400, 400);
}
}
while (!(number >= 1 && number <= 10));
cout << "You have input " << number << endl;
system("PAUSE");
}
You can see the line
(!(number >= 1 && number <= 10))
is repeated. Is there any workaround for this?
int GetNumber()
{
int number;
cout << "Enter an integer." << endl;
cin >> number;
return number;
}
void main()
{
int n = GetNumber();
while(n < 1 || n > 10)
{
Beep(400, 400);
n = GetNumber();
}
cout << "You have input " << n << endl;
system("PAUSE");
}
#include <iostream>
#include <Windows.h>
using namespace std;
void main()
{
int number = 0;
bool invalid_input = true;
do
{
cout << "Enter an integer." << endl;
cin >> number;
invalid_input = !(number >= 1 && number <= 10);
if (invalid_input)
{
Beep(400, 400);
}
}
while (invalid_input);
cout << "You have input " << number << endl;
system("PAUSE");
}
Perhaps...
int number = 0;
while (true)
{
cout << "Enter an integer." << endl;
if (cin >> number && number >= 1 && number <= 10)
break;
Beep(400, 400);
}
cout << "You have input " << number << endl;
system("PAUSE");