Recursive Implementation of atoi()

1.5

The atoi() function takes a string (which represents an integer) as an argument and returns its value.

We have discussed iterative implementation of atoi(). How to compute recursively?

We strongly recommend you to minimize your browser and try this yourself first
The idea is separate the last digit, recursively compute result for remaining n-1 digits, multiply the result with 10 and add the obtained value to last digit.

Below is C implementation of the idea.

// Recursive C program to compute atoi()
#include <stdio.h>
#include <string.h>

// Recursive function to compute atoi()
int myAtoiRecursive(char *str, int n)
{
    // Base case (Only one digit)
    if (n == 1)
        return *str - '0';

    // If more than 1 digits, recur for (n-1), multiplu result with 10
    // and add last digit
    return (10 * myAtoiRecursive(str, n - 1) + str[n-1] - '0');
}

// Driver Program
int main(void)
{
    char str[] = "112";
    int n = strlen(str);
    printf("%d", myAtoiRecursive(str, n));
    return 0;
}

Output:

112

This article is contributed by Narendra Kangralkar. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above

GATE CS Corner    Company Wise Coding Practice

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.

Recommended Posts:



1.5 Average Difficulty : 1.5/5.0
Based on 6 vote(s)










Writing code in comment? Please use ide.geeksforgeeks.org, generate link and share the link here.