Efficiency of string parsing

[Benny the Guard]

I know this sounds like a homework problem, but it's honestly not one. I am writing some code which given an IP address in string format will calculate the integer value of it. Now the trick is I need it to be quick. I see two paths and not sure which would be faster.

1) Use strtok like functionality (actually custom code to make it reentrant and in my case I can change the string) to parse the components of the address. I would also keep a count of the components for error checking.

2) Use sscanf (ip_addr_str, "%d.%d.%d.%d", &c1, &c2, &c3, &c4) and then check the return value to ensure proper formatting (ie 4 components).

Any ides which would be quicker? Any other ideas? My next step is to experiment but was hoping someone could help me avoid writing code multiple times to play with.

[gpraghuram]

I know this sounds like a homework problem, but it's honestly not one. I am writing some code which given an IP address in string format will calculate the integer value of it. Now the trick is I need it to be quick. I see two paths and not sure which would be faster.

1) Use strtok like functionality (actually custom code to make it reentrant and in my case I can change the string) to parse the components of the address. I would also keep a count of the components for error checking.

2) Use sscanf (ip_addr_str, "%d.%d.%d.%d", &c1, &c2, &c3, &c4) and then check the return value to ensure proper formatting (ie 4 components).

Any ides which would be quicker? Any other ideas? My next step is to experiment but was hoping someone could help me avoid writing code multiple times to play with.

If your job is to convert the ip address to integer value then you can use the already existing function inet_addr

Raghuram

[Benny the Guard]

I had thought of that but have a few issues:

1) It does not check for completeness. I need to check that all octets are specified, inet_addr does not do this.

2) I need an unsigned int value, not sure how this equates to in_addr_t

3) Not sure inet_addr checks the octets being bound 0-255. But maybe it does.