C: evaluate part of the string

Question

I cannot find an expression to evaluate part of a string.

I want to get something like this:

if (string[4:8]=='abc') {...} 

I started writing like this:

 if (string[4]=='a' && string[5]=='b' && string[6]=='c') {...} 

but if I need to evaluate most of the string for example

 if (string[10:40] == another_string) {...} 

then he gets a lot of words. Are there any ready-to-use solutions?

Answer 1

You can always use strncmp() , so string[4:8] == "abc" (which is not C syntax, of course) can become strncmp(string + 4, "abc", 5) == 0 .

Answer 2

The standard C library function you want is strncmp . strcmp compares two C strings and, like a regular pattern, version "n" deals with data elements of limited length.

 if(0==strncmp(string1+4, "abc", 4)) /* this bit will execute if string1 ends with "abc" (incluing the implied null) after the first four chars */ 

Answer 3

strncmp other publications are probably the best. If you don't want to use strncmp or just want to know how to implement your own, you can write something like this:

 int ok = 1; for ( int i = start; i <= stop; ++i ) if ( string[i] != searchedStr[i - start] ) { ok = 0; break; } if ( ok ) { } // found it else { } // didn't find it