Count how many number of times a value appears

Question

I want to write a program that tells me how many no. of times a desired value is repeated between 1 to 100 or any other range. Ex:- 9 appears 20 times between 1 to 100.

public class NumberCal {
    public static void main(String []args){
        int counter = 0;
        for(int i=1; i<=100; i++){
            while(i > 0){ 
                int LastDig = i%10;
                if(LastDig == 9){         
                    counter = counter+1 ;     
                    i = i/10;            
                } else{
                    i = i/10;
                }                        
            }     
        }                    
        System.out.println(counter);
    }
}

I tried this but there is no output. Any suggestions?

Answer 1

You're using i for the outer loop but then you also use it for the check and divide it by 10

int counter = 0;
for (int i = 1; i <= 100; i++) {
    int j = i;
    while (j > 0) {
        int LastDig = j % 10;
        if (LastDig == 9) {
            counter = counter + 1;
        }
        j = j / 10;
    }
}
System.out.println(counter);

---

Details

• int i = 1 makes i at 1
• i = i/10 makes i at 0
• i++ makes i at 1
• i = i/10 makes i at 0
• i++ makes i at 1
• infinite loop because you never each 100