# Maximum value of an integer for which factorial can be calculated on a machine

Program to find maximum value of an integer for which factorial can be calculated on a machine, assuming that factorial is stored using basic data type like long long int.

The idea is based on that fact that, in most of the machines, when we cross limit of integer, the values becomes negative.

## C

`// C program to find maximum value of` `// an integer for which factorial can` `// be calculated on your system` `#include <stdio.h>` `int` `findMaxValue()` `{` ` ` `int` `res = 2;` ` ` `long` `long` `int` `fact = 2;` ` ` `while` `(1)` ` ` `{` ` ` `// when fact crosses its size,` ` ` `// it gives negative value` ` ` `if` `(fact < 0)` ` ` `break` `;` ` ` `res++;` ` ` `fact = fact * res;` ` ` `}` ` ` `return` `res - 1;` `}` `// Driver Code` `int` `main()` `{` ` ` `printf` `(` `"Maximum value of integer : %d\n"` `,` ` ` `findMaxValue());` ` ` `return` `0;` `}` |

## Java

`// Java program to find maximum value of` `// an integer for which factorial can be` `// calculated on your system` `import` `java.io.*;` `import` `java.util.*;` `class` `GFG` `{` ` ` `public` `static` `int` `findMaxValue()` ` ` `{` ` ` `int` `res = ` `2` `;` ` ` `long` `fact = ` `2` `;` ` ` `while` `(` `true` `)` ` ` `{` ` ` `// when fact crosses its size,` ` ` `// it gives negative value` ` ` `if` `(fact < ` `0` `)` ` ` `break` `;` ` ` `res++;` ` ` `fact = fact * res;` ` ` `}` ` ` `return` `res - ` `1` `;` ` ` `}` ` ` `// Driver Code` ` ` `public` `static` `void` `main(String[] args)` ` ` `{` ` ` `System.out.println(` `"Maximum value of"` `+` ` ` `" integer "` `+` ` ` `findMaxValue());` ` ` `}` `}` |

## Python3

`# Python3 program to find maximum value of` `# an integer for which factorial can be` `# calculated on your system` `import` `sys` `def` `findMaxValue():` ` ` `res ` `=` `2` `;` ` ` `fact ` `=` `2` `;` ` ` `while` `(` `True` `):` ` ` ` ` `# when fact crosses its size` ` ` `# it gives negative value` ` ` `if` `(fact < ` `0` `or` `fact > sys.maxsize):` ` ` `break` `;` ` ` `res ` `+` `=` `1` `;` ` ` `fact ` `=` `fact ` `*` `res;` ` ` `return` `res ` `-` `1` `;` `# Driver Code` `if` `__name__ ` `=` `=` `'__main__'` `:` ` ` ` ` `print` `(` `"Maximum value of integer:"` `,` ` ` `findMaxValue());` ` ` `# This code is contributed by 29AjayKumar` |

## C#

`// C# program to find maximum value of` `// an integer for which factorial can` `// be calculated on your system` `using` `System;` `class` `GFG` `{` ` ` `public` `static` `int` `findMaxValue()` ` ` `{` ` ` `int` `res = 2;` ` ` `long` `fact = 2;` ` ` `while` `(` `true` `)` ` ` `{` ` ` `// when fact crosses its size,` ` ` `// it gives negative value` ` ` `if` `(fact < 0)` ` ` `break` `;` ` ` `res++;` ` ` `fact = fact * res;` ` ` `}` ` ` `return` `res - 1;` ` ` `}` ` ` `// Driver Code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `Console.Write(` `"Maximum value of"` `+` ` ` `" integer "` `+` ` ` `findMaxValue());` ` ` `}` `}` `// This code is contributed by nitin mittal` |

## PHP

`<?php` `// PHP program to find maximum` `// value of an integer for which` `// factorial can be calculated` `// on your system` `function` `findMaxValue()` `{` ` ` `$res` `= 2;` ` ` `$fact` `= 2;` ` ` `$pos` `= -1;` ` ` `while` `(true)` ` ` `{` ` ` `// when fact crosses its size,` ` ` `// it gives negative value` ` ` `$mystring` `= ` `$fact` `;` ` ` `$pos` `= ` `strpos` `(` `$mystring` `, ` `'E'` `);` ` ` ` ` `if` `(` `$pos` `> 0)` ` ` `break` `;` ` ` `$res` `++;` ` ` `$fact` `= ` `$fact` `* ` `$res` `;` ` ` `}` ` ` `return` `$res` `- 1;` `}` `// Driver Code` `echo` `"Maximum value of"` `.` ` ` `" integer "` `.` ` ` `findMaxValue();` ` ` `// This code is contributed by Sam007` `?>` |

## Javascript

`<script>` `// Javascript program to find maximum` `// value of an integer for which factorial` `// can be calculated on your system` `function` `findMaxValue()` `{` ` ` `let res = 2;` ` ` `let fact = 2;` ` ` ` ` `while` `(` `true` `)` ` ` `{` ` ` ` ` `// When fact crosses its size,` ` ` `// it gives negative value` ` ` `if` `(fact < 0 || fact > 9223372036854775807)` ` ` `break` `;` ` ` ` ` `res++;` ` ` `fact = fact * res;` ` ` `}` ` ` `return` `res - 1;` `}` `// Driver Code` `document.write(` `"Maximum value of"` `+` ` ` `" integer "` `+ findMaxValue());` `// This code is contributed by rag2127` `</script>` |

**Output :**

Maximum value of integer : 20

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