Use sscanf to determine IP address correctness

Because we can see the traversal string to judge one by oneCodeIt is not concise, althoughC LanguageIt is not as good as the scripting language, but there is another sscanf. So I wrote a small function.

 

# Include <stdio. h> <br/> # include <stdlib. h> <br/>/* this function can verify valid IP addresses. The IP address can contain leading 0 or spaces */<br/> int isvalidstr (char * Buf, int * paddr) <br/>{< br/> int Part1, Part2, Part3, part4; <br/> char tail = 0; <br/> int field; <br/> If (BUF = NULL) <br/>{< br/> return 0; <br/>}< br/> Field = sscanf (BUF, "% d. % d. % d. % d % C ", & Part1, & Part2, & Part3, & part4, & tail); <br/> If (field <4 | field> 5) <br/>{< br/> printf ("Keep CT 4 field, get % d /N ", field); <br/> return 0; <br/>}< br/> If (tail! = 0) <br/>{< br/> printf ("ip address mixed with non number/N"); <br/> return 0; <br/>}< br/> If (Part1> = 0 & Part1 <= 255) & (Part2> = 0 & Part2 <= 255) & (Part3> = 0 & Part3 <= 255) & (part4> = 0 & part4 <= 255 )) <br/> {<br/> If (paddr) <br/> * paddr = part4 <24 | Part3 <16 | Part2 <8 | Part1; /* convert to network Order */<br/> return 1; <br/>}< br/> else <br/> {<br/> printf ("not good IP % d: % d/N ", part1, Part2, Part3, part4); <br/>}< br/> return 0; <br/>}< br/> int testip (char * Buf, int unique CT) <br/> {<br/> int result = 0; <br/> int ADDR = 0; <br/> result = isvalidstr (BUF, & ADDR ); <br/> If (result = wrong CT) <br/> {<br/> printf ("OK: valid IP % s, wrong CT % d, get % d/N ", Buf, CT, result); <br/> If (Ct = 1) <br/>{< br/> printf ("/twe convert % s to 0x % x/N", Buf, ADDR ); <br/>}< br/> else <br/> {<br/> printf ("error: valid IP % s, CT % d, get % d/N ", Buf, exact CT, result); <br/>}< br/> return 0; <br/>}< br/> int main (INT argc, char const * argv []) <br/> {<br/>/* empty IP */<br/> testip (null, 0 ); <br/>/* normal IP */<br/> testip ("10.129.43.244", 1 ); <br/>/* IP address with Spaces */<br/> testip ("10.129.43.244", 1); <br/> testip ("10. 129. 43.244 ", 1); <br/>/* IP address with leading 0 */<br/> testip (" 010.129.043.244 ", 1 ); <br/> testip ("010.0129.043.0244", 1); <br/>/* IP address with invalid characters in front */<br/> testip ("x10.129.43.244", 0 ); <br/>/* IP address with invalid characters */<br/> testip ("10.129.43.24y", 0); <br/> testip ("10.129.43.y", 0 ); <br/> return 0; <br/>}< br/>