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Basic math

Hey gang. My question is simple: How do you calculate: int x=1; for(int i=0; i<=1;i++){ int sum= x+i; cout<<sum; } The compiler shows 12 but to be honest as of late I’ve gotten confused on how to calculate the for loops properly. Thank you in advance, Dawid

5th Jan 2019, 11:33 AM
Dawid
Dawid - avatar
8 Answers
+ 3
In for loops you intialized i with 0 and put a condition if i<=1. If that condition satisfied, loops runs. Now, First condition check is 0<=1 is true so it will add value of sum to x+i which will be 1. And then it will print 1. Second condition is 1<=1 which is true. It will again add 1+1 to sum. And prints 2 in output. Third condition will be 2<=1 which is not true so loop will be break.
5th Jan 2019, 11:42 AM
Raj Chhatrala
Raj Chhatrala - avatar
+ 3
p stored a which is the adress of first element of a, and that remains 0. So with *p you're printing a[0] 5 times.
5th Jan 2019, 12:03 PM
HonFu
HonFu - avatar
+ 2
You cout with every iteration, so it's two results: x+0 > 1 x+1 > 2
5th Jan 2019, 11:36 AM
HonFu
HonFu - avatar
+ 2
If you don't put anything into your array but just declare it, there is random stuff at that place in memory, so your output could be anything.
5th Jan 2019, 12:42 PM
HonFu
HonFu - avatar
+ 1
thanks for the answers. So by this logic, the output of the following code: int a[5]; int *p=a; for(int i=0; i<5;i++){ a[i]=i; cout *p; } should be 0,1,2,3,4 but the compiler shows 00000. what al i calculating wrong?
5th Jan 2019, 11:58 AM
Dawid
Dawid - avatar
+ 1
Your code doesn't make sense: int[1]. Can you show the whole code?
5th Jan 2019, 12:27 PM
HonFu
HonFu - avatar
0
Fair enough, makes sense. Now I added the following to the compiler and this came out: int[1]; int x; for(x=0;x<1;x++){ x=a[x]; cout<< x; } compiler shows 7208852. How I try to explain it: we have an array of 2 elements in int [1]. Int x is a variable. The for loop executes, given the condition x=0; and if it‘s less than 1, increment it by one. So far so good. Now lets put that into practise: x=a[x], meaning: 0=a[0], because in the first iteration of the loop x=0, the array srarts at 0 and therefore the output should be 0. How does the compiler calculate 7? And what did I understand wrong?
5th Jan 2019, 12:15 PM
Dawid
Dawid - avatar
0
forgot to add a, its: int a[1];
5th Jan 2019, 12:38 PM
Dawid
Dawid - avatar