C++ keeps skipping my "for" loop [closed] - c++

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I'm trying to create a program that will find a four-digit number that meets four specific requirements: all four digits are different, the thousands number is 3x the tens number, the number is odd, and the sum of the digits is 27. For some reason, despite the program compiling, the for loop won't run and always outputs the initializer number (1000). My main code and the four functions I'm calling are below. I can't figure out why it won't run correctly. I'm completely new to coding so any tips/help are appreciated. Thanks!
main function:
5 //prototypes
6 bool differentDigits(int);
7 bool thouThreeTen(int);
8 bool numberIsOdd(int);
9 bool sumIs27(int);
10
11 #include <iostream>
12 using namespace std;
13
14 int main ()
15 {
16 //variables
17 int n;
18
19 //processing
20
21 for(n=1000;n<=9999;n++)
22 {
23 if(differentDigits(n)==true)
24 {
25 break;
26 }
27
28 if(thouThreeTen(n)==true)
29 {
30 break;
31 }
32
33 if(numberIsOdd(n)==true)
34 {
35 break;
36 }
37
38 if(sumIs27(n)==true)
39 {
40 break;
41 }
42
43 }
44
45 //output
46 cout << n << endl;
47
48 return 0;
49 }
differentDigits function:
3 //Verify all four digits are the same
4
5 #include <iostream>
6 using namespace std;
7
8 bool differentDigits (int n)
9 {
10 int n1, n2, n3, n4;
11
12 n1 = n/1000;
13 n2 = (n/100) % 10;
14 n3 = (n/10) % 10;
15 n4 = n % 10;
16
17 if(n1 != n2 != n3 != n4)
18 {
19 return true;
20 }
21 else
22 {
23 return false;
24 }
25
26 }
thouThreeTen function:
3 //Verify digit in thousands place is 3x the digit in tens place
4
5 #include <iostream>
6 using namespace std;
7
8 bool thouThreeTen(int n)
9 {
10 int n1, n2, n3, n4;
11
12 n1 = n/1000;
13 n2 = (n/100) % 10;
14 n3 = (n/10) % 10;
15 n4 = n % 10;
16
17 if(n1 = (n3 * 3))
18 {
19 return true;
20 }
21 else
22 {
23 return false;
24 }
25
26 }
numberIsOdd function:
3 //Verify that the number is odd
4
5 #include <iostream>
6 using namespace std;
7
8 bool numberIsOdd (int n)
9 {
10 if((n % 2)==1)
11 {
12 return true;
13 }
14 else
15 {
16 return false;
17 }
18
19 }
sumIs27 function:
3 //Verify that the sum of digits is 27
4
5 #include <iostream>
6 using namespace std;
7
8 bool sumIs27(int n)
9 {
10 int n1, n2, n3, n4;
11
12 n1 = n/1000;
13 n2 = (n/100) % 10;
14 n3 = (n/10) % 10;
15 n4 = n % 10;
16
17 if((n1+n2+n3+n4)==27)
18 {
19 return true;
20 }
21 else
22 {
23 return false;
24 }
25
26 }

Answer 1

You have several problems with your code, the first being in main(). If any of the functions return true, you will end the loop. This is probably why you see the for loop as not being executed. Another problem is that in your functions, you are using conditions such as if(n1 = (n3 * 3)) which use the assignment operator instead of checking if they are the same.You want to use if(n1 == (n3 * 3)). Your main should look something like:
int main()
{
int n = 0;
for(n = 1000; n < 9999; ++n)
{
if(differentDigits(n) && thouThreeTen(n) && numberIsOdd(n) && sumIs27(n))
{
break;
}
}
cout << n << endl;
}
In each of your functions, make sure that you are using == not = when you are checking if something is a value.