Easier Done Than Said?

 1 #include <stdio.h>
 2 #include <string.h>
 3 
 4 int main(){
 5     char s[21];
 6     int length;
 7     int i;
 8     int flag1;
 9     int flag2;
10     int flag3;
11     char compareString[6]="aeiou";
12 
13     while(1){
14         scanf("%s",s);
15 
16         if(strcmp(s,"end")==0)
17             break;
18 
19         length=strlen(s);
20         flag1=0;
21         flag2=0;
22         flag3=0;
23 
24         for(i=0;i<length;i++){
25             if(s[i]==‘a‘ || s[i]==‘e‘ || s[i]==‘i‘ || s[i]==‘o‘ || s[i]==‘u‘)
26                 flag1=1;
27         }
28 
29         if(flag1==0){
30             printf("<%s> is not acceptable.\n",s);
31             continue;
32         }
33 
34         for(i=0;i<length-1;i++){
35             if(s[i]==s[i+1] && s[i]!=‘e‘ && s[i]!=‘o‘)
36                 flag2=1;
37         }
38 
39         if(flag2==1){
40             printf("<%s> is not acceptable.\n",s);
41             continue;
42         }
43 
44         for(i=0;i<length-2;i++){
45             if(strchr(compareString,s[i])!=NULL && strchr(compareString,s[i+1])!=NULL && strchr(compareString,s[i+2])!=NULL){
46                 flag3=1;
47                 break;
48             }
49 
50             if(strchr(compareString,s[i])==NULL && strchr(compareString,s[i+1])==NULL && strchr(compareString,s[i+2])==NULL){
51                 flag3=1;
52                 break;
53             }
54             
55         }
56 
57         if(flag3==1){
58             printf("<%s> is not acceptable.\n",s);
59             continue;
60         }
61 
62         printf("<%s> is acceptable.\n",s);
63 
64 
65     }
66     return 0;
67 }