replace word in c

1// here the word post is replaced by the word dak 
2// POST ----> DAK
3
4#include <stdio.h>
5#include <string.h>
6
7void main ()
8{
9    char arr [100];
10    int i,j;
11
12    printf("Enter the array: ");
13    gets(arr);
14
15    for(i=0; i < strlen(arr); i++)
16    {
17        if(arr[i] == 'p' && arr[i+1] == 'o' && arr[i+2] == 's' && arr[i+3] == 't')
18        {
19            arr[i] = 'd';
20            arr[i+1] = 'a';
21            arr[i+2] = 'k';
22
23            j=i+3;
24             
25             // deleting letter "t" from the word "post"
26            while(arr[j-1]!='\0')
27            {
28                arr[j] = arr[j+1];
29                j++;
30            }
31        }
32
33    }
34
35    printf("\n-------------------------------------------------------------------\n");
36    printf("Replaced string: %s\n", arr);
37    printf("-------------------------------------------------------------------\n");
38}
39
40            
41           
42
43
44