If statements in for loops - c++

Question

how do I run only one of those if statements in a for loop? For example i have an input of 5...and i just want it to print five...but whenever i run this code, it will execute all if statement..please help me
#include <iostream>
#include <cstdio>
using namespace std;
int main() {
// Complete the code.
int a;
int b;
cin >> a;
for (a = 0; 0<a<10; a++)
{
if (a == 1)
{
cout << "one";
}
if (a == 2)
{
cout << "two";
}
if (a == 3)
{
cout << "three";
}
if (a == 4)
{
cout << "four";
}
if (a == 5)
{
cout << "five";
}
if (a == 6)
{
cout << "six";
}
if (a == 7)
{
cout << "seven";
}
if (a == 8)
{
cout << "eight";
}
if (a == 9)
{
cout << "nine";
}
else if (a > 9 && a%2 == 0)
{
cout << "even";
}
else if (a > 9 && a&2 != 0)
{
cout << "odd";
}
}
return 0;
}

Answer 1

The problem seems to be the for loop. Your program accepts a value for a as an input, but then as soon as the loop begins, it resets the value of a to 0 (for (a = 0;...
Therefore it's looping 10 times, and on each loop a will have a different value, starting from 0 and ending at 9. This means that all of your if statements will get hit at some point in the execution, generally one on each of the loops round the for.
To get your expected behaviour " input of 5...and i just want it to print five", simply remove the for loop from your code.

Answer 2

Your unnecessary for loop trashes the input value of a and loops forever! (At least until you overflow your signed type a).
You are replacing a by using it as the counter in the for loop! If you only ever want one output, then drop the for loop completely. If your for loop were to remain then your expression 0 < a < 10 ought to be recast as 0 < a && a < 10 : formally 0 < a < 10 is evaluated as (0 < a) < 10 which is either true < 10 or false < 10 which is always true.
Also consider refactoring your if else to set up explicitly mutually exclusive statements:
if (a == 1){
cout << "one";
} else if (a == 2){
cout << "two";
/*and so on*/
} else {
/*all other cases*/
}
Although in this case you might want to consider a switch block:
switch (a){
case 1:
cout << "one";
break; // to stop program control flowing into the next case
case 2:
cout << "two";
break;
/*and so on*/
default:
/*all other cases*/
}

Answer 3

if () {
} else if () {
}
Although,
switch() {
}
will be more efficient in your case.
Update 1
#Aleph0
Below is the solution
int main() {
int a;
cin >> a;
switch (a) {
case 1: cout << "one"; break;
case 2: cout << "two"; break;
case 3: cout << "three"; break;
case 4: cout << "four"; break;
case 5: cout << "five"; break;
case 6: cout << "six"; break;
case 7: cout << "seven"; break;
case 8: cout << "eight"; break;
case 9: cout << "nine"; break;
default: cout << ((a & (1 << 31)) ? "negative" : (a & 1) ? "odd" : "even"); break;
}
}
Question has been asked to do following
i have an input of 5...and i just want it to print five
And, someone has correctly mentioned above, for loop is immaterial here.