how to check if a argument passed is integer

Hi,
how will you sheck if an argument passed through the argv[] is of type integer is their a builtin function in C

Thanks

All arguments passed will be character strings. So even if you called the function with:

Code:

---

%foo 42

---

argv[0] will point to "42", not 42.

Code:

---

#include <stdlib.h>

...

int foo = atoi(argv[0]);

---

should give you an integer, or return 0 if no numbers are found.

> argv[0] will point to "42", not 42.
That's argv[1]

if the argument passed is "45d" atoi("45d") will change it 45. I might be able to use sscanf() to filter that out but was just wondering if their is a neater way of doing it

Use strtol() if you want maximum information back from the conversion as to whether it was successful or not

You can adapt this:
http://faq.cprogramming.com/cgi-bin/...&id=1043284385

well here is a crude way of doing it...
I used to do it before i doscovered atoi..

I take character by cahracter and subtract the ofset ASCII value (Difference between char "1" and number 1 in the ascii chart) and check if it was inside the number range...


but this method is not recommended..

>but this method is not recommended..
Nor is atoi. Use strtol instead if you want to bulletproof your validation code.