# Thread: Finding nth prime number

1. Member Join Date
Apr 2010
Posts
1
Rep Power
0

## Finding nth prime number

I am trying to write a code for a program that will find the n th prime number.As for example 7 is the 4th prime number,11 is the 5th.
The method will take argument as n,and it will find the nth prime number.But I am facing some difficulty with the code.The code doesnt terminate by itself and doesnt return the desired value.Someone please help me out.
Java Code:
```
public class Problem{

/**
* @param args
*/
public int findAns(int n){
int count=0;
int ret=0;
while(count<n){
for(int i=0;i<Integer.MAX_VALUE;i++){
if(ifPrime(i)){
count++;
}
ret=i;
}
}
return ret;
}
public boolean ifPrime(int num){
boolean b=false;
int i;
for (i=2; i < num ;i++ ){
int n = num%i;
if (n==0){
b=false;
break;
}
}
if(i == num){
b=true;
}
return b;
}
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.println(new Problem().findAns(10));
}

}```  Reply With Quote

2. ## Are you sure that you want both a for loop and a while loop here:
Java Code:
```    while(count<n){
for(int i=0;i<Integer.MAX_VALUE;i++){
if(ifPrime(i)){
count++;
}
ret=i;
}
}```
Also, if you correct your indentation, it would make your code a lot easier for others to read, and would help you get more helpful answers. Best of luck.  Reply With Quote

3. Senior Member Join Date
Mar 2010
Posts
266
Rep Power
12

## your

for(int i=0;i<Integer.MAX_VALUE;i++){

will never terminate (well not until you went through all integers). instead, do

for(int i=0;count < n && i<Integer.MAX_VALUE;i++){

and you should be good to go. That's not to say the algorithm could not be improved...  Reply With Quote

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