String manipulations in C 1

[countdrak]

I am trying to read a file name from the cmd line.

%./exec abc.txt

I can read in abc.txt as the argv[1] value. I need to make sure the file is a *.txt file.

I figured, finding the size of argv[1] would give me the number of chars in the file name, and checking the last 3 chars would give me the "txt" part. But sizeof(argv[1]) doesn't work. (Neither does sizeof(argv[1])/sizeof(char) ).

Any help would be appreciated.

 

[countdrak]

Just a side note, I cannot use string.h.

 

[zeitghost]

As I was saying before I was so rudely interrupted:

If you can't use strlen, then count the characters in the string up to the trailing null.

argv[1] is a pointer to char...

 

[countdrak]

Sorry, didn't mean to interrupt.

Thanks, don't know why I didn't think of that. Works fine now.

 

[zeitghost]

You didn't interrupt, the web was doing funny things...

Glad to help.