Automatic funtion

[hazi_]

Hi guys I really need some help with one automatic funtion... It gets a string from the keyboard and checks if this string is a valid file name for Windows (like if it has symbols like ^ or & in it then it's not). It can only have letters from the alphabet, _ , and numbers and ofc. the '.' . Can someone help me fix it I will be very gratefull if you do Thank you! This is my code:

 
 int main() {int stat=0;
int br=0,br1=0;
int ch;
    int i=0;
    char str[256];
    printf("Enter file name:");
    gets(str);
    for(i=0; i<256; i++)
  {
    ch=str[i];
    switch(stat) {
    case 0: 
        if( ch=='A'-'Z' || ch=='a'-'z' ) { br++; stat=1;  break; }
        if(ch=='_') { br++; stat=5; break; }
        else  { stat=7;break;}
        break; 
    case 1:  
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='0'-'9') { br++; stat=5; break;}
        if(ch=='.') { br=0; stat=6;  break; }
        if(ch==':') { br=0; stat=2; break; }
        else { stat=7; break;}
        break; 
    case 2:   
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='_') { br++; stat=5; break; }
        if(ch=='\\') { br1++; stat=3; break; }
        break; 
    case 3:   
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='_') { br++;  stat=4; break;}
        else { stat=7; break;}
        break; 
    case 4:  
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='0'-'9' || ch=='_') { br++; stat=4; break; }
        if(ch=='.') { br=0; stat=6; break; }
        if(ch=='\\') { br1++; stat=3; break; }
        if(br>8 || br1>8) {    stat=7; break;    }
        break; 
    case 5:  
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='0'-'9') { br++; stat=5; break; }
        if(ch=='.') { br=0; stat=6; break; }
        if(br>8) { stat=7; break;    }
        break; 
    case 6:  
        if(ch=='A'-'Z' || ch=='a'-'z' || ch=='_' || ch=='0'-'9'){ br++; stat=6;    break;}
        if(br>3) {    stat=7;  break;}
        break; 
    case 7:  break; 
    }
    
     }
    if(ch==0 && stat!=7) 
printf("Valid name");
     if(stat==7) printf("Name not valid\n");
          return 0; }

[claudiu]

What problems are you having with it specifically? Also note that your checks do not guarantee that the path is valid. Windows also reserves certain names which can't be folder names, etc. For example, if you tried to create a folder called "con" you would be surprised to notice that it is not possible.

[hazi_]

What problems are you having with it specifically? Also note that your checks do not guarantee that the path is valid. Windows also reserves certain names which can't be folder names, etc. For example, if you tried to create a folder called "con" you would be surprised to notice that it is not possible.

No this is not the case... Here we talk only about file names for example you can have test.txt but you can't have something like ^&*$%.txt And this exactly is my problem.. I have a picture of the flow chart that has to be this thing I can post it here too

[dmh2000]

a couple of things that jump out:

gets(str);
for(i=0; i<256; i++)

your input string is not always 256 characters. instead of 256 you should probably use strlen(str) in the loop.

in your tests ch=='A'-'Z' this resolves to ch == (0x41 - 0x5A). probably not what you want. if you are trying to say 'is ch in the range 'A' to 'Z' inclusive' that is not the way to do it. you have to test 'A' and 'Z' separately. like (('A' <= ch)&&(ch <= 'Z'))

using a state machine architecture like you have is the right way to go.

[Salem]

> like (('A' <= ch)&&(ch <= 'Z'))
Or include <ctype.h> and use the likes of isupper()