fork download
copy 
  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12. 		String a = "2147483647";
  13. 		System.out.println("Integer : " + atoi(a));
  14. 	}
  15.  
  16. 	public static int atoi(String a) throws Exception
  17. 	{
  18. 		String sane = checkSanity(a);
  19. 		if( sane == null )
  20. 		{
  21. 			throw new Exception("Not compatible");
  22. 		}
  23.  
  24. 		if( sane.length() > 10 )
  25. 		{
  26. 			throw new Exception("Overflow");
  27. 		}
  28.  
  29. 		if( sane.length() <= 0 )
  30. 		{
  31. 			throw new Exception("Underflow");
  32. 		}
  33.  
  34. 		int convertedInt = 0;
  35. 		int exponent = 0;
  36. 		for( int i = sane.length() - 1; i >= 0 ; i-- )
  37. 		{
  38. 			int newDigit = Character.getNumericValue( sane.charAt(i) );
  39.  
  40. 			int newValueToAdd = (int) ( Math.pow(10, exponent) * newDigit );
  41.  
  42. 			if( convertedInt <= Integer.MAX_VALUE - newValueToAdd )
  43. 			{
  44. 				convertedInt += newValueToAdd;	
  45. 			}
  46. 			else
  47. 			{
  48. 				throw new Exception("Overflow");
  49. 			}
  50.  
  51. 			exponent++;
  52. 		}
  53.  
  54. 		return convertedInt;
  55. 	}
  56.  
  57. 	public static String checkSanity(String a)
  58. 	{
  59. 		// could be null
  60. 		if( a == null )
  61. 		{
  62. 			return null;
  63. 		}
  64.  
  65. 		// Trim leading and trailing spaces.
  66. 		String b = a.trim();
  67.  
  68. 		// Should it have + or - symbol, consider.
  69. 		String c;
  70. 		if( b.charAt(0) == '+' || b.charAt(0) == '-' )
  71. 		{
  72. 			c = b.substring(1);
  73. 		}
  74. 		else
  75. 		{
  76. 			c = b.substring(0);
  77. 		}
  78.  
  79. 		// could have special characters and non numbers.
  80. 		for( int i = 0; i < c.length(); i++ )
  81. 		{
  82. 			if( ! Character.isDigit(c.charAt(i)) )
  83. 			{
  84. 				return null;
  85. 			}
  86. 		}
  87.  
  88. 		return c;
  89. 	}
  90. }
Runtime error #stdin #stdout #stderr 0.1s 320256KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
converted so far: 8
converted so far: 48
converted so far: 648
converted so far: 3648
converted so far: 83648
converted so far: 483648
converted so far: 7483648
converted so far: 47483648
converted so far: 147483648
stderr
copy 
Exception in thread "main" java.lang.Exception: Overflow
	at Ideone.atoi(Main.java:46)
	at Ideone.main(Main.java:13)
https://ideone.com/cmz2Yr
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!