How to Convert String to Number Without Using Integer.parseInt Method Java Program

Program:

Write a program to convert string to number without using Integer.parseInt() method?

Description:

Below example shows how to convert string format of a number to number without calling Integer.parseInt() method. We can do this by converting each character into ascii format and form the number.

Code:

package com.java2novice.algos;

public class MyStringToNumber {

    public static int convert_String_To_Number(String numStr){
        
        char ch[] = numStr.toCharArray();
        int sum = 0;
        //get ascii value for zero
        int zeroAscii = (int)'0';
        for(char c:ch){
            int tmpAscii = (int)c;
            sum = (sum*10)+(tmpAscii-zeroAscii);
        }
        return sum;
    }
    
    public static void main(String a[]){
        
        System.out.println("\"3256\" == "+convert_String_To_Number("3256"));
        System.out.println("\"76289\" == "+convert_String_To_Number("76289"));
        System.out.println("\"90087\" == "+convert_String_To_Number("90087"));
    }
}

Output:

"3256" == 3256
"76289" == 76289
"90087" == 90087

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