dcsimg
Login | Register   
LinkedIn
Google+
Twitter
RSS Feed
Download our iPhone app
TODAY'S HEADLINES  |   ARTICLE ARCHIVE  |   FORUMS  |   TIP BANK
Browse DevX
Sign up for e-mail newsletters from DevX

By submitting your information, you agree that devx.com may send you DevX offers via email, phone and text message, as well as email offers about other products and services that DevX believes may be of interest to you. DevX will process your information in accordance with the Quinstreet Privacy Policy.


Tip of the Day
Language: C++
Expertise: Beginner
Sep 4, 1998

WEBINAR:

On-Demand

Building the Right Environment to Support AI, Machine Learning and Deep Learning


Sizeof or strlen()?

What's wrong with the following code excerpt?
 
const char name[] = "john doe"; //9 characters, null char implicitly added by compiler
size_t namesz = strlen(name); //namesz equals 8!
Nothing, in fact. Code like this does exist and is perfectly legal. However, it's inefficient and error prone: the standard strlen function computes the length of the string at run time, whereas the string length could have been computed at compile-time using of sizeof operator. Furthermore, there's a potential bug that may result from using strlen: it does not count the terminating null character. In order to get a string size correctly, the value returned from strlen has to be incremented by 1. On the other hand, sizeof returns the correct number of characters in a given string, including the terminating null:
 
size_t namesz = sizeof(name); //namesz now equals 9
However, strlen is sometimes unavoidable. A function taking a char [] argument is implicitly transformed by the compiler into a function taking a char *. Similarly, applying the sizeof operator inside a function to its char [] argument is most likely a bug, since it actually returns the size of a pointer, and not the array size! Therefore, sizeof should be used only in the scope in which the array is declared.
Danny Kalev
 
Comment and Contribute

 

 

 

 

 


(Maximum characters: 1200). You have 1200 characters left.

 

 

Sitemap
Thanks for your registration, follow us on our social networks to keep up-to-date