Reverse the non numeric words in a string?

Question

Suppose you are given "Luv you 123 luv me" the expected output is "vuL uoy 123 vul em"

Answer 1

#include <stdio.h>
#include <string.h>

#define MAX_LEN 200

/* 
   This function will reverse the input string,
   i.e content of word.
*/

void reverse_word(char *word, int len)
{
    char *first, *last, temp;

    first = word;
    last = word + len - 1;

    while (last > first) {
        temp = *first;
        *first = *last;
        *last = temp;
        last--;
        first++;
    }
}

int main()
{
    char input_str[MAX_LEN]; //max of 200 char.
    char buff[MAX_LEN];
    char *ptr, *token, *delim = " ";
    int len;

    printf("Please enter the string which you want to convert :\n");

    fgets(input_str, 200, stdin);
    input_str[strlen(input_str) - 1] = '\0'; // for removing the new line (\n) character.

    memset(buff, 0 , 200);
    ptr = buff;

    // it will extract token from the input_str, for more info see "man 3 strtok"
    token = strtok(input_str, delim);    

    while (token != NULL) {

        len = strlen(token);
        if (!isdigit(*token)) {
            reverse_word(token, len); 
        }

        strncpy(ptr, token, len);
        ptr[len] = ' ';
        ptr = ptr + len + 1;

        token = strtok(NULL, delim);
    }

    printf("output : %s\n", buff);

    return 0;
}