Cout更改变量值

Question

In the main function,if i call the cout << answer << "\\n"; , the final answer will be change.Can someone explain to me why this happen ?

#include <iostream>

    using namespace std;

int Even(int *num){

    return (*num)/2;
}


int Odd(int *num){

    return 3*(*num)+1;
}

int Cycle (int num){
        int cycle;

        while (num != 1){

        if( num%2 == 0 ){  

            num= Even(&num) ;

        }else{

            num = Odd(&num) ;
        }

        cycle++;
    }
        return  cycle+1 ;
}



int main(){

    int num1,num2,max=0,answer;

    cin>>num1;
    cin>>num2;

    for(int i = (num1 < num2 ?  num1 : num2) ; i<=num2 ; i++ ){

        answer = Cycle(i);

//Here is the PROBLEM
        cout << answer << "\n";

        if(max < answer){
            max = answer;
        }

    }

    cout <<"Final Answer "<< max <<"\n" ;

  return 0;
}

Input 1 10

Output without cout Final Answer 68 Output with cout Final Answer 20

Answer 1

The problem is not with the cout .

First, your Odd and Even functions should not take pointers, as you are returning the value already.

Second, you're not initializing the variable cycle in the Cycle function.

This code runs correctly:

#include <iostream>
using namespace std;

int Even(int num){

    return (num)/2;
}


int Odd(int num){

    return (3*(num)+1);
}

int Cycle (int num){
    int cycle = 0;

    while (num != 1){

        if( num%2 == 0 ){

            num= Even(num) ;

        }else{

            num = Odd(num) ;
        }

        cycle++;
    }
    return  (cycle+1) ;
}



int main(){

    int num1,num2, max=0, answer;
    cin>>num1;
    cin>>num2;
    for(int i = (num1 < num2 ?  num1 : num2) ; i<=num2 ; i++ ){

        answer = Cycle(i);

        if(max < answer){
            max = answer;
        }

    }

    cout <<"Final Answer "<< max <<"\n" ;

    return 0;
}