Program to Reverse Words in a String - C, C++ Code

Write a C, C++ program to reverse words in a given string. Given an input string, we have to write a code to reverse words of a string.

Programming questions on strings

Suppose, An input string is learn programming.

Input    - learn programming
Output - nrael gnimmargorp

C Program to Reverse Words in a String

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

int main(void) {
 
   // String declaration of max size 100
   char str[100], temp;
   int len, i, j, k;
 
   // Input string
   printf("Enter a string \n");
   gets(str);
 
   len = strlen(str);
 
   for(i = 0, j = 0; i < len; i++) {
  
      // If it's not a alphabet or number 
      if(!isalnum(str[i]) || (i == len - 1)) {
   
        if (i < len - 1) {
            k = i - 1;
        } else {
            k = i;
        }
   
        //Reverse
        while(k > j) {
           temp   = str[j];
           str[j] = str[k];
           str[k] = temp;
           k--;
           j++;
       }
   
       j = i + 1;
    }
  }
 
  printf("%s", str);
 
  return 0;
}

C++ Program to Reverse Words in a String

#include <iostream>
#include <string.h>

using namespace std;

int main() {
 
   char str[100], temp;
   int i, j, k, len;
 
   cout << "Enter a string \n";
   cin.getline(str,100);
 
   len = strlen(str);
 
   for(i = 0, j =0; i < len; i++) {
  
     if(str[i]==' ' || i == len-1){
   
        if(i < len-1) {
           k = i - 1;
        } else {
           k = i;
        }
  
        while (k > j) {
         temp   = str[j];
         str[j] = str[k];
         str[k] = temp;
         j++;
         k--;
      }
  
      j = i + 1;
    }
  }
 
  cout << str;
 
  return 0;
}

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