Home >Backend Development >C++ >How Can You Print Numbers 1 to 1000 Without Loops or Conditional Statements?

How Can You Print Numbers 1 to 1000 Without Loops or Conditional Statements?

Susan Sarandon
Susan SarandonOriginal
2024-11-25 06:53:12855browse

How Can You Print Numbers 1 to 1000 Without Loops or Conditional Statements?

Printing Numbers from 1 to 1000 Without Loops or Conditionals

A challenge posed to programmers is to print numbers from 1 to 1000 without employing any loop structures or conditional statements. This task requires a creative approach to avoid the typical methods for iterating through a range of numbers.

One solution in C or C exploits the recursive nature of function calls. The following code bypasses loops and conditionals:

#include <stdio.h>
#include <stdlib.h>

void main(int j) {
  printf("%d\n", j);
  (&&main + (&exit - &main)*(j/1000))(j+1);
}

Here, the magic lies in the use of function pointers. The &main expression represents the address of the main function, while &exit - &main calculates the size of the function in memory. By multiplying (j/1000) with this value, the function recursively calls itself, shifting its location in memory by the appropriate amount. This allows for incrementing j by 1 and continuing the printing process without any explicit looping mechanism.

Since the original code had issues with pointer arithmetic, an improved version in standard C is provided below:

#include <stdio.h>
#include <stdlib.h>

void f(int j)
{
    static void (*const ft[2])(int) = { f, exit };

    printf("%d\n", j);
    ft[j/1000](j + 1);
}

int main(int argc, char *argv[])
{
    f(1);
}

In this version, a static array of function pointers is utilized to avoid the pointer arithmetic concerns. The main function initializes the array with two elements: f itself for continuing the recursion and exit for when the final j value is reached, signaling the end of the process.

The above is the detailed content of How Can You Print Numbers 1 to 1000 Without Loops or Conditional Statements?. For more information, please follow other related articles on the PHP Chinese website!

Statement:
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn